g(m2)-ganglioside and Gangliosidoses

Topics: Diagnosis, Differential; G(M2) Activator Protein; G(M2) Ganglioside; Gangliosidoses; Humans; Lysosomes; Prognosis; Proteins

Topics: Animals; Diagnosis, Differential; G(M2) Activator Protein; G(M2) Ganglioside; Gangliosidoses; Humans; Mutation; Prognosis; Proteins

Although there is only one documented function carried out by the GM2 activator protein in the lysosome, new information suggests that other less obvious roles may also be played by this protein in vivo. This information includes data demonstrating that the GM2 activator is a secretory, as well as a lysosomal protein, and that cells possess a carbohydrate-independent mechanism to re-capture the activator, with or without bound lipid, from the extracellular fluid. Additionally the GM2 activator has been shown to bind, solubilize and transport a broad spectrum of lipid molecules, such as glycolipids, gangliosides and at least one phosphoacylglycerol, between liposomes. At pH 7 the GM2 activator's rate of lipid transport is reduced by only 50% from its maximum rate which is achieved at approx. pH 5, suggesting that the GM2 activator may serve as a general intra- and/or inter-cellular lipid transport protein in vivo. Since the late 1970s the lysosomal form of the GM2 activator has been known to act as a substrate-specific co-factor for the hydrolysis of GM2 ganglioside by beta-hexosaminidase A. Gangliosides are a class of negatively charged glycolipids particularly abundant in neuronal cells which have been linked to numerous in vivo functions, such as memory formation and signal transduction events. Deficiency of the GM2 activator protein results in the storage of GM2 ganglioside and severe neurological disease, the AB-variant form of GM2 gangliosidosis, usually culminating in death before the age of 4 years. The exact mode-of-action of the GM2 activator in its role as a co-factor, and its specificity for various glycolipids are currently matters of debate in the literature.

Topics: Animals; beta-N-Acetylhexosaminidases; Biological Transport; G(M2) Activator Protein; G(M2) Ganglioside; Gangliosidoses; Glycolipids; Humans; Hydrolysis; Liposomes; Proteins

Tay-Sachs disease and Sandhoff disease are severe neurodegenerative disorders caused by a deficiency of beta-hexosaminidase A and resultant accumulation of its substrate, GM2 ganglioside, in neuronal lysosomes. The three clinical forms of the disorders (infantile, juvenile and adult) are of varying severity and onset, and have been correlated with the amount of residual GM2 ganglioside-degrading activity present in patients' cells. Through targeted disruption of the murine beta-hexosaminidase genes in embryonic stem cells, we have developed a set of mice that vary in their GM2 ganglioside-degrading capacity and exhibit many of the clinical features of the human diseases. These mice are valuable for the study of pathogenic mechanisms and for devising novel therapeutic strategies in these disorders.

Topics: Adult; Animals; beta-N-Acetylhexosaminidases; Child; Disease Models, Animal; G(M2) Ganglioside; Gangliosidoses; Gene Targeting; Humans; Infant; Lysosomes; Mice; Neurons; Sandhoff Disease; Stem Cells; Tay-Sachs Disease

Most lysosomal storage disorders are known as pediatric diseases. In recent years late onset and adult forms of these disorders have been recognized. The adult form of a given lysosomal storage disorder differs from the childhood disease in several respects. Adult disorders are, with some exceptions, less common than the childhood diseases. The clinical picture is not only less severe, but often shows quite different clinical signs and symptoms than the early onset form. Metachromatic leucodystrophy, GM1 and GM2 gangliosidoses, Gaucher disease and aspartylglucosaminuria are presented as examples of lysosomal storage disorders manifesting as adult diseases. The differences of the early and late onset disorders are discussed in the light of recent results of molecular genetics, residual enzyme activity and pseudodeficiency.

Topics: Acetylglucosamine; Adult; Age of Onset; Aspartylglucosaminuria; G(M2) Ganglioside; Gangliosidoses; Gangliosidosis, GM1; Gaucher Disease; Humans; Leukodystrophy, Metachromatic

Adult GM2 gangliosidosis is a rare disorder that often presents with both neurological and psychiatric syndromes. Effective treatment of the psychotic and affective symptoms associated with this disorder has been complicated by poor treatment response and the concern that many psychotropic agents may worsen the underlying gangliosidosis. We report the successful use of electroconvulsive therapy for treatment of severe depression in a young man with adult GM2 gangliosidosis.

Topics: Adult; beta-N-Acetylhexosaminidases; Combined Modality Therapy; Depressive Disorder; Electroconvulsive Therapy; Fluoxetine; G(M2) Ganglioside; Gangliosidoses; Hallucinations; Humans; Male; Neurocognitive Disorders

Topics: Amino Acid Sequence; beta-N-Acetylhexosaminidases; G(M2) Ganglioside; Gangliosidoses; Gene Frequency; Genes; Humans; Incidence; Molecular Biology; Molecular Sequence Data; Mutation; Spinal Muscular Atrophies of Childhood

The authors describe the clinical phenotypes of hexosaminidase deficiencies (GM2 gangliosidosis). The symptoms, differently combined, include cerebellar ataxia, motor neuron disease, dystonia, psychosis, neurovegetative troubles with different severity. Morphological changes are evident in rectal, muscle or nerve biopsies. Minor clinical changes are described in carriers from a family. A chronic GM2 gangliosidosis has to be suspected in any atypical case with the above-mentioned symptoms with autosomal-recessive inheritance.

Topics: Adolescent; Adult; beta-N-Acetylhexosaminidases; Biopsy; Cerebellar Ataxia; Child; Diagnosis, Differential; Dystonia; Electrodiagnosis; G(M2) Ganglioside; Gangliosidoses; Genes, Recessive; Genetic Carrier Screening; Humans; Motor Neuron Disease; Neurocognitive Disorders; Pedigree; Phenotype; Radiography; Sandhoff Disease; Tay-Sachs Disease

Clinical phenotypes of GM2-gangliosidosis are complex. In the past 5 years it has become possible to dissect out the phenotypic complexity on the basis of abnormalities on the DNA level. Available data on the 18 disease-causing mutations so far identified in the beta-hexosaminidase alpha-gene allow an oversimplified generalization; mutations that produce no or highly unstable mRNA cause the most severe infantile forms of the disease, while all late-onset forms are due to point mutations within the protein-coding region, which generate stable mRNA and stable mutant protein. The mutation underlying the distinct phenotype of Jewish adult Tay-Sachs disease will be discussed separately by Navon. The prototype of juvenile Tay-Sachs disease is the B1 variant. The disease was first recognized by an apparent discrepancy in the beta-hexosaminidase activities toward the conventional artificial substrates and the natural lipid substrate, GM2-ganglioside. When assayed with the conventional artificial substrates, patients appear reasonably normal while they are severely deficient in hydrolysis of the natural substrate (and more recently the 'sulfated' artificial substrate). The majority of B1 patients fall in the clinical category of juvenile GM2-gangliosidosis. Some of the earlier juvenile patients reported to have partial hexosaminidase A deficiency are likely to be B1 variant. Two point mutations, occurring at a mutation hot spot, CpG, and both affecting the same codon, have been described as the causes of the B1 variant phenotype; G533----A, Arg178----His; and C532----T, Arg178----Cys. The latter mutation has been found so far only in one Czechoslovakian family. In contrast, the former mutation has a wide geographic and ethnic distribution.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Alleles; beta-N-Acetylhexosaminidases; Binding Sites; Catalysis; Child; Child, Preschool; DNA Mutational Analysis; Female; G(M2) Ganglioside; Gangliosidoses; Genes; Genotype; Hexosaminidase A; Humans; Infant; Male; Models, Molecular; Phenotype; Protein Conformation; Tay-Sachs Disease

Topics: alpha-Galactosidase; Arylsulfatases; beta-Galactosidase; Cystine; Fabry Disease; G(M1) Ganglioside; G(M2) Ganglioside; Galactosylceramidase; Gangliosidoses; Genetic Carrier Screening; Glycoproteins; Heparitin Sulfate; Humans; Hydrolases; Isoelectric Focusing; Isoenzymes; Kinetics; Leukodystrophy, Globoid Cell; Leukodystrophy, Metachromatic; Lipid Metabolism, Inborn Errors; Lysosomes; Metabolism, Inborn Errors; Molecular Weight; Mucolipidoses; Niemann-Pick Diseases; Sphingolipidoses; Sphingomyelin Phosphodiesterase

Topics: Animals; Cattle; Enzyme Activation; G(M1) Ganglioside; G(M2) Ganglioside; Gangliosidoses; Glucosylceramidase; Glycolipids; Glycosphingolipids; Hexosaminidases; Humans; Leukodystrophy, Metachromatic; Lysosomes; Mice; Protein Binding; Proteins; Rats; Substrate Specificity; Sulfatases

Topics: Animals; beta-N-Acetylhexosaminidases; Biodegradation, Environmental; Cattle; G(M2) Ganglioside; Galactosyltransferases; Gangliosides; Gangliosidoses; Guinea Pigs; Hexosaminidases; Humans; N-Acetylgalactosaminyltransferases; Polypeptide N-acetylgalactosaminyltransferase; Sandhoff Disease; Tay-Sachs Disease

Topics: Adolescent; Adult; Animals; beta-Galactosidase; Cats; Cerebrovascular Disorders; Child, Preschool; Coronary Disease; Fabry Disease; Female; G(M1) Ganglioside; G(M2) Ganglioside; Gangliosidoses; Gaucher Disease; Glycolipids; Hexosaminidases; Humans; Infant; Infant, Newborn; Leukodystrophy, Globoid Cell; Leukodystrophy, Metachromatic; Male; Sodium-Potassium-Exchanging ATPase; Vascular Resistance

Topics: Adolescent; beta-Galactosidase; Brain Diseases, Metabolic; Child; Child, Preschool; Clinical Enzyme Tests; Female; G(M1) Ganglioside; G(M2) Ganglioside; Gangliosidoses; Humans; Infant; Infant, Newborn; Isoenzymes; Mass Screening; Metabolism, Inborn Errors; Models, Genetic; Phenotype; Pregnancy; Prenatal Diagnosis; Sandhoff Disease; Tay-Sachs Disease

Topics: G(M1) Ganglioside; G(M2) Ganglioside; G(M3) Ganglioside; Gangliosidoses; Genetic Carrier Screening; Genetic Counseling; Glycoside Hydrolases; Humans; Leukodystrophy, Metachromatic; Lipidoses; Mucopolysaccharidoses; Mucopolysaccharidosis I; Mucopolysaccharidosis III; Mucopolysaccharidosis IV; Mucopolysaccharidosis VI; Phenotype; Polymorphism, Genetic

Topics: Animals; Cats; Cattle; Disease Models, Animal; Dogs; G(M2) Ganglioside; Gangliosidoses; Gaucher Disease; Glycogen; Glycogen Storage Disease Type II; Glycopeptides; Humans; Leukodystrophy, Globoid Cell; Leukodystrophy, Metachromatic; Lipidoses; Lysosomes; Mannosidases; Metabolism, Inborn Errors; Mice; Niemann-Pick Diseases; Rabbits; Sphingolipids

Topics: Brain; G(M1) Ganglioside; G(M2) Ganglioside; Gangliosides; Gangliosidoses; Humans; Lipidoses

The gangliosidoses are hereditary diseases with a recessive mode of inheritance and are caused by a genetically induced enzymatic block, which results in the accumulation of gangliosides in various tissues of the body, mainly in the brain. Although Tay-Sachs disease, the most commonly occurring of the gangliosidoses, has been known for nearly 100 years, additional variants of ganglioside "storage" disorders have been discovered during the past 15 years. Considerable progress in the knowledge of these disorders has been made with the advent of electron microscopy and with the elaboration of new biochemical and enzyme-chemical techniques. At the present the gangliosidoses are not amenable to therapy. Therefore the foreseeable future the pragmatic approach involves identification of the high-risk pregnancy and antenatal diagnosis.

Topics: Axons; Cerebellum; Cerebral Cortex; Cerebrosides; Female; Fetal Diseases; G(M2) Ganglioside; Gangliosidoses; Humans; Inclusion Bodies; Lipidoses; Muscles; Neurons; Optic Nerve; Pregnancy; Retina; Spinal Cord

GM1 and GM2 gangliosidoses are progressive neurodegenerative lysosomal storage diseases resulting from the excessive accumulation of GM1 and GM2 gangliosides in the lysosomes, respectively. The diagnosis of gangliosidosis is carried out based on comprehensive findings using various types of specimens for histological, ultrastructural, biochemical and genetic analyses. Therefore, the partial absence or lack of specimens might have resulted in many undiagnosed cases. The aim of the present study was to establish immunohistochemical and immunofluorescent techniques for the auxiliary diagnosis of canine and feline gangliosidoses, using paraffin-embedded brain specimens stored for a long period.. Using hematoxylin and eosin staining, cytoplasmic accumulation of pale to eosinophilic granular materials in swollen neurons was observed in animals previously diagnosed with GM1 or GM2 gangliosidosis. The immunohistochemical and immunofluorescent techniques developed in this study clearly demonstrated the accumulated material to be either GM1 or GM2 ganglioside.. Immunohistochemical and immunofluorescent techniques using stored paraffin-embedded brain specimens are useful for the retrospective diagnosis of GM1 and GM2 gangliosidoses in dogs and cats.

Topics: Animals; Brain; Cat Diseases; Cats; Dog Diseases; Dogs; Fluorescent Antibody Technique; G(M1) Ganglioside; G(M2) Ganglioside; Gangliosidoses; Immunohistochemistry; Paraffin Embedding; Reproducibility of Results; Retrospective Studies

The ganglioside-activator protein is an essential cofactor for the lysosomal degradation of ganglioside GM2 (GM2) by beta-hexosaminidase A. It mediates the interaction between the water-soluble exohydrolase and its membrane-embedded glycolipid substrate at the lipid-water interphase. Mutations in the gene encoding this glycoprotein result in a fatal neurological storage disorder, the AB variant of GM2-gangliosidosis. In order to efficiently and sensitively probe the glycolipid binding and membrane activity of this cofactor, we synthesized two new fluorescent glycosphingolipid (GSL) probes, 2-NBD-GM1 and 2-NBD-GM2. Both compounds were synthesized in a convergent and multistep synthesis starting from the respective gangliosides isolated from natural sources. The added functionality of 2-aminogangliosides allowed us to introduce the chromophore into the region between the polar head group and the hydrophobic anchor of the lipid. Both fluorescent glycolipids exhibited an extremely low off-rate in model membranes and displayed very efficient resonance energy transfer to rhodamine-dioleoyl phosphoglycerol ethanolamine (rhodamine-PE) as acceptor. The binding to GM2-activator protein (GM2AP) and the degrading enzyme was shown to be unaltered compared to their natural analogues. A novel fluorescence-resonance energy transfer (FRET) assay was developed to monitor in real time the protein-mediated intervesicular transfer of these lipids from donor to acceptor liposomes. The data obtained indicate that this rapid and robust system presented here should serve as a valuable tool to probe quantitatively and comprehensively the membrane activity of GM2AP and other sphingolipid activator proteins and facilitate further structure-function studies aimed at delineating independently the lipid- and the enzyme-binding mode of these essential cofactors.

Topics: Animals; beta-N-Acetylhexosaminidases; Brain; Carbohydrate Sequence; Catalysis; Cattle; Chromatography, Thin Layer; Fluorescence Resonance Energy Transfer; Fluorescent Dyes; G(M1) Ganglioside; G(M2) Activator Protein; G(M2) Ganglioside; Gangliosides; Gangliosidoses; Glycolipids; Glycoproteins; Humans; Lipids; Models, Chemical; Molecular Sequence Data; Mutation; Spectrometry, Fluorescence; Sphingolipid Activator Proteins; Sphingolipids; Structure-Activity Relationship; Tay-Sachs Disease; Time Factors

To determine the clinical features and biochemical basis of the first Japanese patient with the GM2 gangliosidosis AB variant.. The clinical manifestations and laboratory findings in the patient were investigated. Cultured fibroblasts from the patient were analyzed by means of immunofluorescence staining with an anti-GM2 ganglioside monoclonal antibody and thin-layer chromatography and immunostaining. GM1 ganglioside catabolism in cultured cells was analyzed by pulse labeling, and the amount of GM2 activator in cells was determined by Western blot analysis. Gene analysis was performed according to standard protocols.. The patient showed progressive neurologic manifestations of quite early onset. Muscular weakness and hypotonia became evident by 1 month of age, and the patient then developed a startle reaction, severe psychomotor retardation, and myoclonic seizures. Immunocytochemical analysis clearly revealed the accumulation of GM2 ganglioside in cultured fibroblasts from the patient, and thin-layer chromatography confirmed it. Western blot and metabolic studies showed a complete deficiency of GM2 activator. Gene analysis did not reveal any mutations in the protein coding region of the GM2 activator gene.. The clinical features and biochemical basis of this Japanese patient with GM2 gangliosidosis AB variant were determined. Immunocytochemical analysis using cultured fibroblasts as samples is available for the diagnosis of this disease.

Topics: Anticonvulsants; Blotting, Western; Cells, Cultured; Chromatography, Thin Layer; Electroencephalography; Epilepsies, Myoclonic; Fibroblasts; G(M2) Ganglioside; Gangliosidoses; Genetic Variation; Humans; Immunohistochemistry; Infant; Japan; Male; Psychomotor Performance; Pyridoxine

The function of the GM2 activator protein is to act as a substrate-specific cofactor in the hydrolysis of GM2 ganglioside by beta-hexosaminidase A. Mutations in the gene encoding it result in the AB variant form of GM2 gangliosidosis. One such mutation, Cys138 Arg, results in the mutant protein being retained and degraded in the endoplasmic reticulum of mammalian cells. In order to characterize the biochemical effects of this substitution, we expressed the mutant protein in transformed bacteria. We first compared the wild-type protein produced by two bacterial expression methods, one requiring protein refolding, with activator purified from the medium of transfected CHO cells. The "activity" and circular dichroism spectrum (alpha-helical content) of all three proteins were similar, justifying the use of refolded activator from transformed bacteria in structure/function studies. Second, the mutant protein was expressed in both bacterial systems and in each retained approximately 2% of the wild type's specific activity. The presence of even this small amount of activity in the mutant protein coupled with a calculated alpha-helical content nearly identical to the wild type, strongly suggest that no major tertiary or secondary structural changes, respectively, had occurred due to the mutation. However, we demonstrate that its heat stability at 60 degrees C is reduced 14-fold, suggesting some localized change in tertiary structure. The loss of a disulfide loop was confirmed by reacting the mutant protein with Ellman's reagent. A kinetic analysis detected a large increase in the apparent K(m) of beta-hexosaminidase A for the mutant; however, there was no apparent change in Vmax. A fluorescence dequenching assay was used to evaluate the ability of the mutant protein to transport lipids and bind GM2 ganglioside. These assays detected no difference between the wild-type and mutant proteins, indicating that the Cys138 Arg substitution has no effect on these functions. We conclude that the mutation specifically affects a domain in the activator protein that is responsible for the recognition of the activator-GM2 ganglioside complex by beta-hexosaminidase A.

Topics: Amino Acid Sequence; Amino Acid Substitution; Animals; Arginine; beta-N-Acetylhexosaminidases; CHO Cells; Cricetinae; Cysteine; Disulfides; Escherichia coli; G(M2) Activator Protein; G(M2) Ganglioside; Gangliosidoses; Genetic Variation; Molecular Sequence Data; Oligopeptides; Peptides; Protein Folding; Proteins; Recombinant Fusion Proteins

Lysosomal degradation of ganglioside GM2 by hexosaminidase A requires the presence of a small, non-enzymatic cofactor, the GM2-activator protein (GM2AP). Lack of functional protein leads to the AB variant of GM2-gangliosidosis, a fatal lysosomal storage disease. Although its possible mode of action and functional domains have been discussed frequently in the past, no structural information about GM2AP is available so far. Here, we determine the complete disulfide bond pattern of the protein. Two of the four disulfide bonds present in the protein were open to classical determination by enzymatic cleavage and mass spectrometry. The direct localization of the remaining two bonds was impeded by the close vicinity of cysteines 136 and 138. We determined the arrangement of these disulfide bonds by MALDI-PSD analysis of disulfide linked peptides and by partial reduction, cyanylation and fragmentation in basic solution, as described recently (Wu F, Watson JT, 1997, Protein Sci 6:391-398).

Topics: Amino Acid Sequence; Disulfides; Endopeptidases; G(M2) Activator Protein; G(M2) Ganglioside; Gangliosidoses; Humans; Molecular Sequence Data; Peptide Fragments; Protein Conformation; Protein Folding; Protein Structure, Secondary; Proteins; Recombinant Proteins; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization

Tay-Sachs and Sandhoff diseases are autosomal recessive neurodegenerative diseases resulting from the inability to catabolize GM2 ganglioside by beta-hexosaminidase A (Hex A) due to mutations of the alpha subunit (Tay-Sachs disease) or beta subunit (Sandhoff disease) of Hex A. Hex B (beta beta homodimer) is also defective in Sandhoff disease. We previously developed mouse models of both diseases and showed that Hexa-/- (Tay-Sachs) mice remain asymptomatic to at least 1 year of age while Hexb-/- (Sandhoff) mice succumb to a profound neurodegenerative disease by 4-6 months of age. Here we find that neuron death in Hexb-/- mice is associated with apoptosis occurring throughout the CNS, while Hexa-/- mice were minimally involved at the same age. Studies of autopsy samples of brain and spinal cord from human Tay-Sachs and Sandhoff diseases revealed apoptosis in both instances, in keeping with the severe expression of both diseases. We suggest that neuron death is caused by unscheduled apoptosis, implicating accumulated GM2 ganglioside or a derivative in triggering of the apoptotic cascade.

Topics: Animals; Apoptosis; beta-N-Acetylhexosaminidases; Child, Preschool; Disease Models, Animal; G(M2) Ganglioside; Gangliosidoses; Gene Deletion; Hexosaminidase A; Hexosaminidase B; Humans; Infant; Mice; Neurons; Sandhoff Disease; Tay-Sachs Disease

Mutations in the hexosaminidase A gene (HEXA) causing the B1 variant of GM2-gangliosidosis result in the presence of a mutant enzyme protein with a catalytically defective alpha subunit. A rare and panethnically distributed mutation, transition G533A (Arg178His), is known to be a common allele among Portuguese patients with the subacute phenotype. We now report the presence of an Arg178His allele in three Portuguese sibs with a chronic form of the disease, who carry the transition G755A (Arg252His) on the second allele. This novel mutation is the first B1 allele to be associated with an adult phenotype.

Topics: Adult; Alleles; Amino Acid Sequence; Arginine; beta-N-Acetylhexosaminidases; DNA Mutational Analysis; G(M2) Ganglioside; Gangliosidoses; Hexosaminidase A; Histidine; Humans; Molecular Sequence Data; Pedigree; Phenotype; Polymerase Chain Reaction; Polymorphism, Single-Stranded Conformational; Portugal

GM1- and GM2-gangliosides were isolated from brain and radiolabelled. The labelled moieties were localized by hydrolysis with lysosomal enzymes, followed by thin-layer chromatography of the products. High-resolution loading tests with labelled gangliosides were developed and found to differentiate infantile and juvenile forms of GM1- and GM2-gangliosidoses as well as the identification of B, O and AB types of GM2-gangliosidosis.

Topics: Animals; Brain Chemistry; Chromatography, Thin Layer; Diagnosis, Differential; Fibroblasts; G(M1) Ganglioside; G(M2) Ganglioside; Gangliosidoses; Gangliosidosis, GM1; Genetic Variation; Humans; Kinetics; Mice; Sandhoff Disease; Tay-Sachs Disease

Ganglioside analysis and quantitative Golgi studies of the cerebral cortex of cats with ganglioside and nonganglioside lysosomal storage diseases reveal a correlation between the amount of accumulated GM2 ganglioside and the extent of ectopic dendrite growth on cortical pyramidal neurons. This correlation was not observed with any of the other gangliosides assayed for, including GM1 ganglioside. These results suggest a specific role for GM2 ganglioside in the initiation of ectopic neurites on pyramidal cells in vivo and are consistent with the developing hypothesis that different gangliosides have specific roles in different cell types dependent upon the receptor or other effector molecules with which they may interact.

Topics: Aging; Animals; Carbohydrate Metabolism, Inborn Errors; Cat Diseases; Cats; Cerebral Cortex; Dendrites; G(M2) Ganglioside; Gangliosidoses; Pyramidal Cells; Reference Values

Development of a strategy for efficient delivery of exogenous enzyme to neuronal lysosomes is essential to achieve enzyme replacement in neurodegenerative lysosomal storage diseases. We tested whether effective lysosomal targeting of the human enzyme beta-N-acetylhexosaminidase A (Hex A; beta-N-acetyl-D-hexosaminide N-acetylhexosaminohydrolase, EC 3.2.1.52) can be obtained by coupling it via disulfide linkage to the atoxic fragment C of tetanus toxin (TTC) that is bound avidly by neuronal membrane. TTC-Hex A conjugation resulted in neuronal surface binding and enhanced endocytosis of enzyme as observed in immunofluorescence studies with rat brain cultures. In immunoelectrophoretic quantitative uptake studies, rat neuronal cell cultures contained 16- and 40-fold greater amounts of enzyme after incubation with TTC-Hex A than with nonderivatized Hex A. In cerebral cortex cell cultures from a feline model of human GM2 gangliosidosis (Tay-Sachs and Sandhoff diseases), binding and uptake patterns of the enzymes were similar to those in the rat brain cell cultures. After exposure to extracellular concentrations of enzyme attainable in vivo, lysosomal storage of immunodetectable GM2 ganglioside was virtually eliminated in neurons exposed to TTC-Hex A, whereas a minimal effect was observed with Hex A. These findings demonstrate the usefulness of TTC adducts for effective neuronal lysosomal enzyme replacement.

Topics: Animals; Antibodies, Monoclonal; beta-N-Acetylhexosaminidases; Brain; Cats; Cells, Cultured; Cerebral Cortex; Drug Carriers; Embryo, Mammalian; Fluorescent Antibody Technique; G(M2) Ganglioside; Gangliosidoses; Hexosaminidase A; Immunoelectrophoresis; Lysosomes; Neurons; Peptide Fragments; Rats; Rats, Inbred Strains; Tetanus Toxin; Toxins, Biological

The AB-variant form of GM2 gangliosidosis is an inherited lysosomal storage disease. Biochemical data have linked its cause to the lack of a functional GM2 activator protein (activator). In the present study we identify a mutation in the gene encoding the activator protein of an AB-variant patient. These data represent direct evidence that the disease in the patient described here is a result of mutations at the Activator gene locus. A T412----C transition was found in the homozygous form in cDNA and genomic DNA from the patient. This nucleotide change would result in the substitution of Cys138 by an Arg residue in the activator protein. Whereas the patient's fibroblasts produce apparently normal levels of activator mRNA, they lack a functional activator protein. Transfection of either a construct containing the normal activator cDNA, pAct1, or a cDNA construct containing the T----C transition caused COS-1 cells to transcribe high levels of activator mRNA. Lysates from cells transfected with pAct1 produced an elevated level of both pro- and mature forms of the activator protein, with an accompanying 11-fold enhancement in the ability of purified hexosaminidase A to hydrolyze GM2 ganglioside. However, lysates from cells transfected with the mutant cDNA construct contained only low levels of the pro-activator protein, which failed to enhance hexosaminidase A activity significantly above the endogenous level of mock transfected COS cells. We conclude that the T412----C transition in the GM2 Activator gene of the patient is responsible for the disease phenotype.

Topics: Base Sequence; Blotting, Northern; Blotting, Western; Cell Line; Cloning, Molecular; G(M2) Activator Protein; G(M2) Ganglioside; Gangliosidoses; Molecular Sequence Data; Mutation; Polymerase Chain Reaction; Proteins

GM2-gangliosidosis B1 variant is thought to be a rare disorder with a wide geographical and ethnic distribution. We report the biochemical findings obtained in different specimens from a group of 11 B1 variant patients originating from the north of Portugal. The biochemical data obtained seem to indicate that only one of these patients is a genetic compound presenting a clinical and biochemical pattern similar to the majority of B1 variant patients described in the literature, but somewhat different from the profile presented by the other patients reported here, who are homozygous for the 'DN-allele'.

Topics: Acetylglucosamine; beta-N-Acetylhexosaminidases; Child; Child, Preschool; Electrophoresis, Cellulose Acetate; Fibroblasts; G(M2) Ganglioside; Gangliosidoses; Genetic Variation; Heterozygote; Homozygote; Humans; Hymecromone; Leukocytes; Lymphocytes; Portugal

Adult GM2 gangliosidosis is a rare autosomal recessive disease with widely varying neurological and psychiatric manifestations. It is caused by marked deficiency, but not total absence, of beta-hexosaminidase (Hex) A, due to a single base change in the alpha-subunit gene of Hex, resulting in a substitution of Ser for Gly at position 269 in the alpha-subunit of the enzyme. The same mutation was identified in all investigated patients, most of whom are Ashkenazi Jews. Among previously studied non-Jewish patients of unrelated families this mutation appears either homozygously or in compound heterozygosity with an unidentified alpha-subunit mutation, whereas all Ashkenazi patients are compound heterozygotes. In all but one of them the other mutation is one of the Ashkenazi infantile Tay-Sachs alleles, while in one 76-year-old woman with very mild neurological symptoms, it is an unidentified alpha-subunit mutation. At present, the little correlation that seems to exist between these different genotypes and the severity of the disease poses a serious dilemma for genetic counselors.

Topics: Adult; Aged; Base Sequence; beta-N-Acetylhexosaminidases; DNA Mutational Analysis; DNA Probes; Female; G(M2) Ganglioside; Gangliosidoses; Gene Frequency; Genes; Genes, Recessive; Genotype; Heterozygote; Hexosaminidase A; Humans; Jews; Molecular Sequence Data; Protein Precursors; Tay-Sachs Disease

GM2-gangliosidoses are neurological disorders caused by a genetic deficiency of either the beta-hexosaminidase A or the GM2 activator, a glycolipid binding protein. In a patient with an immunologically proven GM2 activator protein deficiency, A T412----C transition (counted from A of the initiation codon) was found in the coding sequence, which results in the substitution of Arg for the normal Cys107 in the mature GM2 activator protein. The remainder of the coding sequence remained entirely normal.

Topics: Base Sequence; DNA; DNA Mutational Analysis; G(M2) Activator Protein; G(M2) Ganglioside; Gangliosidoses; Humans; Molecular Sequence Data; Polymerase Chain Reaction; Proteins

Optical light and electron microscopy were used in studies into two cases of infantile GM2-gangliosidosis. The results are reported in this paper. The correlation has been evident between histological and ultrastructural findings. Reliable delimitation between two different variants of infantile GM2-gangliosidosis was achieved through biochemical investigation of postmortally cultured skin fibroblasts. A classical form with isolated hexosaminidase-A defect (Tay-Sachs disease) was distinguished from a second variant with complete defect of both isoenzymes of hexosaminidase (Sandhoff's disease). Biochemical investigation of postmortally cultured fibroblasts today has become indispensable to enlargement of autopsy findings from other storage diseases, as well.

Topics: Brain; Cells, Cultured; Diagnosis, Differential; Female; Fibroblasts; G(M2) Ganglioside; Gangliosidoses; Humans; Infant; Male; Microscopy, Electron; Sandhoff Disease; Tay-Sachs Disease

Juvenile GM2 gangliosidosis is a rare neurodegenerative disorder closely related to Tay-Sachs disease but of later onset and more protracted course. The biochemical defect lies in the alpha-subunit of the lysosomal enzyme beta-hexosaminidase. Cultured fibroblasts derived from patient A synthesized an alpha-subunit which could acquire mannose 6-phosphate and be secreted, but which failed to associate with the beta-subunit to form the enzymatically active heterodimer. By contrast, fibroblasts from patient B synthesized an alpha-subunit that was retained in the endoplasmic reticulum. To identify the molecular basis of the disorder, RNA from fibroblasts of these two patients was reverse-transcribed, and the cDNA encoding the alpha-subunit of beta-hexosaminidase was amplified by the polymerase chain reaction (PCR) in four overlapping fragments. The PCR fragments were subcloned and shown by sequence analysis to contain a G to A transition corresponding to substitution of histidine for arginine at position 504 in the case of patient A and at position 499 in the case of patient B. The mutations were confirmed by hybridization of allele-specific oligonucleotides to PCR-amplified fragments of DNA corresponding to exon 13 of the alpha-subunit gene. The Arg504----His mutation was found on both alleles of patient A as well as of another unrelated patient; the homozygosity of this mutant allele is attributable to consanguinity in the two families. The Arg499----His mutation was found in patient B in compound heterozygosity with a common infantile Tay-Sachs allele. There is additional heterogeneity in juvenile GM2 gangliosidosis, as neither mutation was found in the DNA of a fourth patient. The Arg----His mutations at positions 499 and 504 are located at CpG dinucleotides, which are known to be mutagenic "hot spots."

Topics: Arginine; Base Sequence; beta-N-Acetylhexosaminidases; Cells, Cultured; Child; Child, Preschool; DNA; Female; Fibroblasts; G(M2) Ganglioside; Gangliosidoses; Histidine; Homozygote; Humans; Lysosomes; Macromolecular Substances; Male; Molecular Sequence Data; Mutation; Nucleic Acid Hybridization; Polymerase Chain Reaction; Transcription, Genetic

Congenital glycolipidoses of the nervous system cause accumulation of various storage substances in cells. Methods of lipid and lectin histochemistry were used in an attempt for classification by known groups of diseases, on the basis of stored lipids. While conventional methods of lipid histochemistry enabled classification of accumulated substances only by lipid classes, lectin approaches provided additional information on sugar bonding points in cases of glycosphingolipidoses. For example, HPR-labelled and FITC-labelled WGA was positively recorded from neurons in cases of GM 2-gangliosidoses and mucopolysaccharidoses, type HURLER. Particular interest was aroused by RCA-I and PNA-positive reactions in glial cells of globoid cell leucodystrophy, since no histochemical method had been available in the past for diagnosis of this storage disease. Hence, the findings recorded by ALROY et al. (1986) from Twitcher mice, an animal model of galactosylceramidosis, have been confirmed by human material.

Topics: G(M2) Ganglioside; Gangliosidoses; Histocytochemistry; Humans; Lectins; Leukodystrophy, Globoid Cell; Leukodystrophy, Metachromatic; Lipid Metabolism, Inborn Errors; Lipids; Mucopolysaccharidoses; Nervous System Diseases; Neurons; Niemann-Pick Diseases; Tay-Sachs Disease

Chronic and adult-onset GM2 gangliosidoses are neurological disorders caused by marked deficiency of the A isoenzyme of beta-hexosaminidase; they occur in the Ashkenazi Jewish population, though less frequently than classic (infantile) Tay-Sachs disease. Earlier biosynthetic studies had identified a defective alpha-subunit that failed to associate with the beta-subunit. We have now found a guanosine to adenosine transition at the 3' end of exon 7, which causes substitution of serine for glycine at position 269 of the alpha-subunit [designated 269 (Gly----Ser) substitution]. An RNase protection assay was used to localize the mutation to a segment of mRNA from fibroblasts of a patient with the adult-onset disorder. That segment of mRNA (after reverse transcription) and a corresponding segment of genomic DNA were amplified by the polymerase chain reaction and sequenced by the dideoxy method. The sequence analysis, together with an assay based on the loss of a ScrFI restriction site, showed that the patient was a compound heterozygote who had inherited the 269 (Gly----Ser) mutation from his father and an allelic null mutation from his mother. The 269 (Gly----Ser) mutation, in compound heterozygosity with a presumed null allele, was also found in fetal fibroblasts with an association-defective phenotype and in cells from five patients with chronic GM2 gangliosidosis. It was not found in beta-hexosaminidase A-deficient cells obtained from patients with infantile Tay-Sachs disease nor in cells from individuals who do not have beta-hexosaminidase A deficiency. However, there must be additional mutations with similar consequences, since the 269 (Gly----Ser) substitution was not present in fibroblasts from two patients with juvenile GM2 gangliosidosis even though these had an association-defective alpha-subunit.

Topics: Adult; Base Sequence; beta-N-Acetylhexosaminidases; Cells, Cultured; Europe; Fibroblasts; G(M2) Ganglioside; Gangliosidoses; Glycine; Humans; Isoenzymes; Jews; Macromolecular Substances; Molecular Sequence Data; Mutation; Reference Values; Serine

Beta-hexosaminidase activity and the effects of ganglioside storage on neuronal function were examined in a German shorthair pointer (GSHP) with progressive neurodegenerative signs. Morphologic evidence of neuronal storage and massive accumulation of GM2 ganglioside were present. Beta-hexosaminidase activity in plasma, liver, kidney, and brain, assayed with use of unsulfated fluorogenic substrates, was normal. There was no pathologic accumulation or aberrant localization of phosphorylated neurofilaments in neurons. Activity of cortical neurotransmitter synthesizing enzymes, choline acetyltransferase, and glutamate decarboxylase was unaffected. Ligand binding to carrier sites for choline high affinity uptake identified with [3H]hemicholinium-3 was increased, whereas post-synaptic binding to muscarinic cholinergic ([3H]QNB) and gamma-aminobutyric acid receptors ([3H]muscimol) was reduced.

Topics: Animals; beta-N-Acetylhexosaminidases; Brain; Brain Chemistry; Choline O-Acetyltransferase; Dog Diseases; Dogs; Female; G(M2) Ganglioside; Gangliosides; Gangliosidoses; Glutamate Decarboxylase; Kidney; Liver; Neurons; Receptors, Neurotransmitter; Spinal Cord

Fibroblasts from a patient with GM2-gangliosidosis B1 variant contained mRNA of normal size but in reduced quantity for the beta-hexosaminidase alpha subunit. The nucleotide sequence of a cDNA clone that included the entire protein coding sequence was completely normal except for a single base substitution from G to A at no. 533, resulting in a change from arginine to histidine at amino acid no. 178. The same mutation was found in two other cDNA clones. The position of the mutation is approximately 90 amino acids from the N-terminus of the mature, processed enzyme. Computer analysis predicted substantial alterations in the secondary structure of the enzyme protein. These results provide new insight into functional domains of this enzyme.

Topics: Amino Acid Sequence; Base Sequence; beta-N-Acetylhexosaminidases; DNA; Fibroblasts; G(M2) Ganglioside; Gangliosidoses; Humans; Molecular Sequence Data; Mutation; Protein Conformation; RNA, Messenger

Tay-Sachs disease displays a variety of forms on the clinical and biochemical level. On the molecular level it has been shown, that poly (A)+ RNA preparations from fibroblasts of patients with classical Tay-Sachs disease lack detectable alpha-chain message when analyzed by Northern blotting with complementary DNA encoding the alpha-chain of human beta-hexosaminidase A. In this report the p beta H alpha-5 clone was used to investigate whether patients with two different variants of Tay-Sachs disease also lack the alpha-chain message. On the basis of RNA hybridization analyses, we could show that our patients which synthesize an altered alpha-chain, as judged by testing enzyme activity and substrate specificity, have the 2.1 kb mRNA which is also seen in healthy control patients.

Topics: beta-N-Acetylhexosaminidases; Cell Line; Fibroblasts; G(M2) Ganglioside; Gangliosidoses; Gene Expression Regulation; Humans; Male; Nucleic Acid Hybridization; RNA, Messenger; Tay-Sachs Disease

A point mutation within exon 5 of beta-hexosaminidase alpha chain gene was identified earlier in a Puerto Rican patient with GM2-gangliosidosis B1 variant (the DN-allele) [K. Ohno and K. Suzuki: J. Neurochem. 50:316-318, 1988]. Oligonucleotide probes designed to detect either the normal or the DN-allele showed that four additional patients carried the same mutation. These patients were of Italian, French, Spanish, and English/Italian/Hungarian origin. Three of them, as well as our original patient, were compound heterozygotes with positive signals for both the mutant and normal probes, while the Spanish patient was positive only for the DN-allele. A patient from Czechoslovakia was negative for the DN-allele. Thus, the specific mutation originally found in the Puerto Rican patient has a surprisingly wide geographic and ethnic distribution. This mutation can account for the B1 variant phenotype in five of the six B1 variant patients so far examined.

Topics: Alleles; beta-N-Acetylhexosaminidases; Czechoslovakia; DNA Probes; Exons; France; G(M2) Ganglioside; Gangliosidoses; Germany; Heterozygote; Humans; Hungary; Italy; Mutation; Nucleic Acid Hybridization; Puerto Rico; Spain; United States

Adult hexosaminidase A deficiency is a form of GM2 gangliosidosis with autosomal recessive inheritance. Only 35 cases (mostly among Ashkenazic Jews) have been reported worldwide. Symptoms include, in a third of the cases, psychosis. A 27-year-old sufferer with no prior psychiatric history, developed a post-partum psychosis, with affective and hebephrenic components, 3 days following her first delivery. She responded to lithium within 10 days of initiating treatment; the full episode lasted 1 month. We conclude that lithium is the preferred treatment for psychosis in such adult patients, especially in light of possible long-term neurological deterioration caused by phenothiazines. Ashkenazic Jews with atypical neurological syndromes presenting with psychosis should be tested for hexosaminidase A deficiency.

Topics: Adult; beta-N-Acetylhexosaminidases; Female; G(M2) Ganglioside; Gangliosidoses; Hexosaminidase A; Humans; Lithium; Lithium Carbonate; Pregnancy; Psychotic Disorders; Puerperal Disorders

Lectin histochemical studies were performed on paraffin-embedded brain, spinal cord and eye sections of 16 animals from four different species affected with GM1- and GM2-gangliosidosis to identify specific carbohydrate residues in the perikaryon of neurons. We examined tissues from cats, cattle and dogs with GM1-gangliosidosis and from cats, dogs, and swine with GM2-gangliosidosis and compared them to corresponding normal animals. In all but two cases, the neurons stained intensely with Concanavalia ensiformis agglutinin (Con A); in 12 cases they stained with Dolichos biflorus agglutinin; in 10 cases with Ulex europaeus agglutinin-I; in 9 cases with Griffonia simplicifolia-I; and 8 with soybean agglutinin. Neurons from control tissues stained weakly with Con A, but not with any of the other lectins used. Similar staining patterns of neurons were noted in animals affected with the same disorder originating from the same mutant line. These findings highlight the fact that in gangliosidosis, the lectin staining patterns of neurons may be influenced by the deficiency in enzyme activity and by additional unknown but inherited factors.

Topics: Animals; Brain; Cats; Cattle; Concanavalin A; Dogs; Endothelium; G(M1) Ganglioside; G(M2) Ganglioside; Gangliosides; Gangliosidoses; Lectins; Plant Lectins; Species Specificity; Swine; Wheat Germ Agglutinins

The biochemical basis of a case of GM2 gangliosidosis in a Japanese Spaniel was studied. This dog had a massive accumulation of GM2 ganglioside in the brain. The beta-hexosaminidase activity in this affected dog brain was approximately 12 times higher than that of normal brain. However, the activity toward p-nitrophenyl-6-sulfo-2-acetamido-2-deoxyglucopyranoside was only four times higher in the affected brain than in normal brain. The GM2 activator preparation obtained from the normal dog brain could stimulate the hydrolysis of GM2 ganglioside by beta-hexosaminidase isolated from the affected dog. However, the corresponding activator fraction from the affected dog could not stimulate such a reaction. It was concluded that the biochemical basis of the GM2 gangliosidosis in this Japanese Spaniel was due to the attenuation in the stimulatory activity of GM2 activator. This case represents the first animal form similar to the activator deficiency (or defect) of Type AB GM2 gangliosidosis in humans.

Topics: Animals; beta-N-Acetylhexosaminidases; Brain; Dog Diseases; Dogs; G(M2) Ganglioside; Gangliosides; Gangliosidoses; Humans; Hydrolysis; Isoenzymes

4-Methylumbelliferyl-N-acetylglucosamine-6-sulfate (4MUGLc6S) which is known to be a specific substrate for human hexosaminidase A was used to determine enzymatic features of canine GM2-gangliosidosis. The enzyme activity using 4MUGlc6S in affected dog brain and liver was less than 20 to 30% of control tissues, whereas total 4-methylumbelliferyl beta-glucosaminidase activity in canine GM2-gangliosidosis was normal or elevated. However, when beta-hexosaminidase was fractionated by DEAE-Sepharose column chromatography, beta-hexosaminidase A like fraction in affected dog tissues was reduced to 20 to 30% of control. These data suggest that canine GM2-gangliosidosis is analogous to human juvenile.

Topics: Animals; beta-N-Acetylhexosaminidases; Chromatography, DEAE-Cellulose; Disease Models, Animal; Dog Diseases; Dogs; G(M2) Ganglioside; Gangliosidoses; Hexosaminidase A; Hymecromone; Isoenzymes

Confirmation of deficient beta-hexosaminidase activity in suspected cases of GM2 gangliosidosis may be difficult with available assay systems if the residual activity is high (as in many juvenile cases and genetic compounds). Hexosaminidase activity is normal in the AB-variant (activator protein deficiency), although GM2-ganglioside (GM2) catabolism is severely impaired. We therefore examined ganglioside degradation in intact fibroblasts in culture. Intracellular ganglioside levels were determined in cultured human skin fibroblasts grown in standard tissue culture medium or medium supplemented with mixed bovine brain gangliosides. Cellular uptake and catabolism of the added gangliosides were manifested by modest increases in the intracellular concentrations of gangliosides GT + GD and GM1 in all cells tested, and marked accumulation of GM2 in fibroblasts from patients with GM2 gangliosidoses. Intracellular GM2 increased five- to fifteen-fold in all of the GM2 gangliosidosis cell lines tested, including those from patients with infantile Tay-Sachs disease (TSD), Sandhoff disease, late infantile and juvenile variants of TSD with high residual enzyme activity, adult onset GM2 gangliosidosis, and the AB-variant. Significant GM2 accumulation did not occur in fibroblasts from patients with GM2 gangliosidosis grown in standard medium, or in normal fibroblasts grown in ganglioside enriched medium. Our method of ganglioside feeding employs commercially available materials and no special equipment. It should be useful for the confirmation of impaired GM2 catabolism in a variety of settings.

Topics: beta-N-Acetylhexosaminidases; Cells, Cultured; Culture Media; Female; Fibroblasts; G(M2) Ganglioside; Gangliosides; Gangliosidoses; Hexosaminidases; Humans; Kinetics; Male; Sandhoff Disease; Tay-Sachs Disease

Topics: G(M2) Ganglioside; Gangliosidoses; Humans

A 24-year-old man presented with dystonia, dementia, amyotrophy, choreoathetosis, and ataxia. Partial hexosaminidase A deficiency was documented in serum and leukocytes and confirmed by rectal biopsy with ganglion cells containing membranous cytoplasmic bodies. A brief review of the literature reveals that tremor, dystonia and choreoathetosis are common but neglected symptoms associated with chronic GM2 gangliosidosis.

Topics: Adult; Athetosis; Chorea; Dystonia; G(M2) Ganglioside; Gangliosidoses; Humans; Male; Movement Disorders; Syndrome

A child with AB variant GM2 gangliosidosis who had progressive intellectual deterioration and seizures commencing at the age of 12 months is described. Neuronal loss, and neuronal and astrocytic inclusions characteristic of the gangliosidoses, were seen on cortical biopsy. GM2 ganglioside was detected in the CSF. As CNS ganglioside accumulation in this condition occurs in the presence of normal leukocyte hexosaminidase A and B levels, spinal fluid assay for GM2 ganglioside may serve as a valuable aid in diagnosis.

Topics: Cerebral Cortex; G(M2) Ganglioside; Gangliosides; Gangliosidoses; Hexosaminidases; Humans; Infant; Leukocytes; Male; Neurons

The internalization of exogenous mixed brain gangliosides in ML IV cultured skin fibroblasts indicated an impairment of ganglioside catabolism in these cells. Incubation of ML IV, normal and various other lysosomal storage disorders cell lines for five days with exogenous tritium labelled GM3, GD1a or GT1 gangliosides allowed accurate quantitation of the retained gangliosides. This in vitro approach provides a reliable method for the diagnosis of ML IV.

Topics: Cells, Cultured; Child; Child, Preschool; Fibroblasts; G(M2) Ganglioside; G(M3) Ganglioside; Gangliosides; Gangliosidoses; Humans; Infant; Mucolipidoses

A storage disease in a 2-year-old Japanese Spaniel resembled a GM2 gangliosidosis previously identified in a now extinct line of German Shorthaired Pointers. Despite a later appearance of signs in the Japanese Spaniel, the distribution, staining, and ultrastructure of the stored material were similar in the two breeds. Golgi studies of cerebral cortical neurons revealed the formation of spiny and aspiny enlargements at the axon hillock region (meganeurites) and the growth of secondary neurites from this region. As in the German Shorthaired Pointer model, there was massive storage of GM2 ganglioside as well as a seemingly paradoxical increase in total beta-hexosaminidase activity measured in vitro.

Topics: Animals; beta-N-Acetylhexosaminidases; Dog Diseases; Dogs; Female; G(M2) Ganglioside; Gangliosides; Gangliosidoses; Golgi Apparatus; Hexosaminidases; Lysosomes; Microscopy, Electron

Cell hybridizations between fibroblasts of four variants (B, O, AB, and B1) of infantile GM2 gangliosidosis were performed. Cocultivated as well as hybrid cells were analyzed for their capability to degrade exogenously added [3H]-GM2. Hybridization of variant AB fibroblasts with fibroblasts of variant O, variant B, or variant B1 resulted in an enhanced rate of GM2 hydrolysis, showing intergenic complementation. Similar restoration of GM2 catabolism was observed after hybridization of variant B1 cells with variant O, but not with variant B cells. These results indicate that B1 cells carry a mutation in the gene locus for the alpha-subunit of beta-hexosaminidase. Studies of the processing of immature enzyme in variant B1 cells showed the presence of alpha-precursors and mature alpha-chains, but at a lower level as compared to normal cells.

Topics: beta-N-Acetylhexosaminidases; Electrophoresis, Polyacrylamide Gel; Fibroblasts; G(M2) Ganglioside; Gangliosidoses; Genetic Complementation Test; Hexosaminidases; Humans; Hybrid Cells; Hydrolysis; Infant; Tay-Sachs Disease

Topics: beta-N-Acetylhexosaminidases; Catalysis; Cell Line; Fibroblasts; G(M2) Ganglioside; Gangliosidoses; Hexosaminidase A; Humans; Hymecromone; Skin

Neurochemical studies were performed on synaptosomal membranes from cats with GM1 or GM2 gangliosidosis to examine possible mechanisms of neuronal dysfunction in these disorders. The basic hypothesis tested was that deficient ganglioside catabolism causes increased ganglioside content of synaptosomal plasma membrane which in turn disrupts normal function. Fluidity characteristics of synaptosomal membranes were examined using fluorescence polarization. Results showed markedly reduced membrane fluidity in both GM1 and GM2 gangliosidosis. These results were supported by a second study which revealed that isolated synaptosomal membranes of GM1 gangliosidosis cats had a 24-fold increase in total ganglioside content caused predominantly by excess GM1, a 2.3-fold increased cholesterol content, and a 1.4-fold increased phospholipid content. Finally, kinetic analysis of synaptosomal plasma membrane Na+,K+-ATPase from cats with GM1 gangliosidosis showed negligible differences in kinetic parameters compared with controls. Thus, the enzyme appeared protected from the global membrane changes in fluidity and composition. These observations provide evidence for a pathogenetic mechanism of neuronal dysfunction in the gangliosidoses while demonstrating protection of certain vital functional components, such as Na+,K+-ATPase.

Topics: Animals; Brain; Cats; Cholesterol; Fluorescence Polarization; G(M1) Ganglioside; G(M2) Ganglioside; Gangliosidoses; Humans; Lipids; Membrane Fluidity; Phospholipids; Sodium-Potassium-Exchanging ATPase; Synaptic Membranes; Temperature

Ganglioside GM2, 3H-labeled in the sphingoid base, was added to the culture medium of normal and GM2 gangliosidosis fibroblasts. Ganglioside was found to adsorb rapidly to the cell surface, most of it could however be removed by trypsination. The trypsin-resistant incorporation was about 10 nmol/mg cell protein, after 48 h. The rates of adsorption and incorporation depended strongly on the concentration of fetal calf serum in the medium, higher serum concentrations being inhibitory. After various incubation times, the lipids were extracted, separated by thin-layer chromatography and visualized by fluorography. In normal cells a variety of degradation products as well as sphingomyelin was found whereas in GM2 gangliosidosis cells, only trace amounts of such products (mainly GA2) were found. In contrast, the higher gangliosides GM1 and GD1a were formed in comparable amounts (2.2-3.6% of total radioactivity after 92 h) in normal and pathologic cell lines. Supplementation of cells from GM2 gangliosidosis, variant AB, with purified GM2-activator protein restored ganglioside GM2 degradation to almost normal rates but had no effect on its glycosylation to gangliosides GM1 and GD1a. From these results we conclude that the synthesis of higher gangliosides from incorporated GM2 can occur by direct glycosylation and not only via lysosomal degradation and resynthesis from [3H]sphinganine-containing degradation products. Preliminary studies with subcellular fractionation after various times of [3H]ganglioside incorporation indicated biphasic kinetics for the net transport of membrane-inserted ganglioside to lysosomes, compatible with the notion that a portion of the glycolipids can also escape from secondary lysosomes and migrate to Golgi compartment or cell surface.

Topics: Animals; Biological Transport; Cells, Cultured; Chromatography, Ion Exchange; Chromatography, Thin Layer; Fibroblasts; G(M2) Ganglioside; Gangliosides; Gangliosidoses; Humans; Lipid Metabolism; Skin; Subcellular Fractions

The biosynthesis and secretion of lysosomal GM2-activator was studied in fibroblasts from controls and patients of GM2 gangliosidosis metabolically labelled with [3H]-leucine. Immunoprecipitation was performed with affinity-purified antibodies to human kidney GM2-activator protein. Normal fibroblasts and fibroblasts of variant B and O of GM2 gangliosidosis secrete GM2-activator protein as a 24-kDa polypeptide, which is able to stimulate degradation of ganglioside GM2 by beta-hexosaminidase A in the in vitro assay. In the presence of 10mM NH4Cl the rate of secretion is twice as high as in normal fibroblasts. Intracellularly, GM2-activator protein is represented in these cell lines by polypeptides with apparent molecular masses ranging from 21 kDa-22.5 kDa. Under the same labelling conditions, in two cell lines of patients with variant AB of infantile GM2 gangliosidosis intracellularly only traces of GM2-activator were detectable, whereas significant amounts of polypeptides with molecular masses between 25 and 26.5 kDa could be precipitated from the media of these fibroblasts.

Topics: Cells, Cultured; Endocytosis; Enzyme-Linked Immunosorbent Assay; Fibroblasts; G(M2) Activator Protein; G(M2) Ganglioside; Gangliosides; Gangliosidoses; Humans; Kinetics; Leucine; Leupeptins; Lysosomes; Pepstatins; Phenylmethylsulfonyl Fluoride; Protein Biosynthesis; Skin; Tritium

Gangliosidoses are very rare neurological diseases based on specific enzyme defects. They constitute models for the disruption of specific metabolic pathways and cellular functions with the ultimate consequence of manifest clinical symptoms. The investigation of the various steps involved in the generation of a given syndrome can therefore lead to a more profound understanding of the cell biology of the nervous system. In the present synopsis we try to briefly summarize some aspects of the present knowledge of pathophysiological mechanisms in GM1- and GM2-gangliosidoses.

Topics: beta-Galactosidase; beta-N-Acetylhexosaminidases; Brain; Child; G(M1) Ganglioside; G(M2) Activator Protein; G(M2) Ganglioside; Gangliosides; Gangliosidoses; Glycoproteins; Hexosaminidases; Humans; Lysosomes; Nerve Degeneration; Protein Deficiency; Proteins; Saposins; Sphingolipid Activator Proteins; Synaptic Transmission

Neurophysiological studies (EEG, ERG, VEP and BAEP) have been carried out on a total of fifty-four patients (fourty-five GM2 and nine GM1 gangliosidosis) at various stages of the disease process. In infantile GM2 gangliosidosis, the EEG was midly abnormal from an early age but by the age of one year there was a rapid and progressive deterioration. EEG changes in late onset GM2 gangliosidosis were very variable and unrelated to age or enzyme defect. In both Type 1 and Type 2 GM1 gangliosidosis there was a progressive deterioration of the EEG. Paroxysmal features were not prominent in any of the gangliosidoses, despite the occurrence of seizures. The ERG remained normal in both GM2 and GM1 patients. In the infantile GM2 patients there was progressive loss of the VEP between nine and fifteen months of age but the timing of VEP changes were more variable in all the other groups. Evidence of brainstem dysfunction was found in one of the two TSD patients tested. The combined neurophysiological features appear to be characteristic for each group of gangliosidosis and differ from other neurometabolic disorders of childhood.

Topics: Arousal; Brain; Child; Child, Preschool; Electroencephalography; Electroretinography; Evoked Potentials; G(M1) Ganglioside; G(M2) Ganglioside; Gangliosides; Gangliosidoses; Humans; Infant; Sandhoff Disease; Synaptic Transmission; Tay-Sachs Disease

Topics: Axons; Cell Line; Child; G(M1) Ganglioside; G(M2) Ganglioside; Gangliosides; Gangliosidoses; Humans; Motor Endplate; Motor Neurons; Muscles; Nerve Degeneration; Nerve Growth Factors; Nerve Regeneration; Neuromuscular Junction; Neurons; Peripheral Nerves; Synaptic Transmission

GM1 and GM2 gangliosidoses are progressive neurodegenerative diseases which accumulate intralysosomal gangliosides--and to a lesser extent oligosaccharides--chiefly in the central and peripheral nervous system owing to deficiencies of beta-galactosidase and hexosaminidases A or/and B, respectively. This intralysosomal "storage" in neuronal pericarya and their processes, and subsequent loss of such nerve cells provide the background for clinical symptoms of the central nervous system and the retina, while involvement of the peripheral nervous system and the visceral organs largely remains free of clinical findings. The morphological involvement of the latter organs is widespread though varying, thus allowing morphological investigations of lymphocytes, skin, or rectum for morphological diagnosis and as a screening procedure.

Topics: Astrocytes; Brain; Child; Dendrites; G(M1) Ganglioside; G(M2) Ganglioside; Gangliosides; Gangliosidoses; Humans; Inclusion Bodies; Lysosomes; Microscopy, Electron; Nerve Degeneration; Neurons; Peripheral Nerves; Sandhoff Disease; Spinal Cord; Synaptic Membranes; Tay-Sachs Disease; Vacuoles

The chemical and enzymatic features in tissues of GM2-gangliosidosis are characterized by the analysis of glycolipids and FD-MS, and also by enzymatic analysis with DEAE-Sepharose column chromatography. The results suggest that canine GM2-gangliosidosis is equivalent to human juvenile GM2-gangliosidosis.

Topics: Animals; beta-N-Acetylhexosaminidases; Brain Chemistry; Chromatography, Thin Layer; Dog Diseases; Dogs; G(M2) Ganglioside; Gangliosides; Gangliosidoses; Hexosaminidases; Humans; Kidney; Liver; Mass Spectrometry; Sialic Acids

Topics: beta-Galactosidase; beta-N-Acetylhexosaminidases; Brain; Child; Fibroblasts; G(M1) Ganglioside; G(M2) Activator Protein; G(M2) Ganglioside; Gangliosides; Gangliosidoses; Glycoproteins; Hexosaminidases; Humans; Lysosomes; Mutation; Protein Deficiency; Proteins; Sandhoff Disease; Saposins; Sphingolipid Activator Proteins; Tay-Sachs Disease

A 10-year-old boy developed progressive dystonia and dementia. His symptoms had begun at age 2 1/2 years, and he had been unable to walk by 8 years. At age 10 he was severely dystonic, unable to use his hands to feed himself, and almost anarthric . He had dysphagia and urinary incontinence, and functioned at a 4-year-old level of mental development. The mean percentages of beta-hexosaminidase A measured in serum, leukocytes, and fibroblasts by the heat denaturation method, each on three separate assays, were 5.9, 9.8, and 13.0%, respectively. These values are higher than in Tay-Sachs disease but are similar to levels seen in late-onset or adult cases of GM2 gangliosidosis. This patient appears to represent a new phenotype of juvenile GM2 gangliosidosis having dystonia as the dominant symptom.

Topics: Child; Dystonia; Fibroblasts; G(M2) Ganglioside; Gangliosidoses; Hexosaminidases; Humans; Leukocytes; Male; Phenotype

p-Nitrophenyl-6-sulfo-2-acetamido-2-deoxy-beta-D-glucopyranoside, which is known to be a specific substrate for human hexosaminidase A, has recently been used successfully for diagnosis of variants B and B1 of GM2-gangliosidosis (Fuchs et al. 1983; Kytzia et al. 1983; Li et al. 1983). However, it is hydrolyzed by hexosaminidase S as well and is therefore not suitable for detection of patients with variant 0, who reach the normal range of activity toward this substrate. Assay of ganglioside GM2 cleaving activity in fibroblast extracts in the presence of the natural GM2 activator protein reveals residual hexosaminidase A activities of less than 2% of normal controls in two infantile and up to 7.5% in two juvenile patients with variant 0.

Topics: Acetylglucosamine; Cells, Cultured; Fibroblasts; G(M2) Ganglioside; Gangliosidoses; Genetic Variation; Glucosamine; Hexosaminidases; Humans; Hymecromone; Isoelectric Focusing; Skin; Substrate Specificity

Topics: Animals; beta-N-Acetylhexosaminidases; Brain; Cat Diseases; Cats; Disease Models, Animal; G(M2) Ganglioside; Gangliosidoses; Hexosaminidases; Humans

Topics: Aging; Atrophy; Biopsy; Cerebral Cortex; Child, Preschool; Computers; Dendrites; Female; G(M2) Ganglioside; Gangliosidoses; Humans; Infant; Infant, Newborn; Intellectual Disability; Microscopy, Electron; Models, Neurological; Motor Cortex; Neurons; Pregnancy; Synapses; Synaptic Transmission; Visual Cortex

A patient is described whose clinical course and pathologic features, including massive brain storage of GM2 ganglioside in grey matter, are identical with those of classical Tay-Sachs disease despite normal levels of beta -N-acetyl hexosaminidase and normal isozyme distribution. The kinetic properties and thermolability of the patient's hexosaminidase are normal. Crude extracts of a postmortem sample of patient's liver can catalyze the hydrolysis of 5.1 pmoles of labeled GM2 ganglioside/16 h/mg of protein (control liver = 69.9 pmoles/16 h/mg). Addition of partially purified human liver hexosaminidase A activator protein stimulated the hydrolysis of substrate by the patients liver extract by 27-fold compared to 3-fold for control livers. Measurement of "activator" in enriched fractions of patient's and control liver showed a reduced (25-30% of control) amount of stimulation of hexosaminidase A catalyzed hydrolysis of GM2 ganglioside as well as of Asialo-GM2 ganglioside. The addition of sphingomyelin to reaction mixtures, which is known to inhibit surfactant stimulation of hexosaminidase A, reduced activation of hexosaminidase A by patient's liver preparation to undetectable levels. Polyacrylamide gel electrophoresis of enriched preparations of control and patient's liver showed a rapidly migrating protein band in control liver corresponding to the activator protein and the absence of this protein band in the patient's liver.

Topics: Brain; Brain Chemistry; G(M2) Ganglioside; Gangliosides; Gangliosidoses; Glycoproteins; Hexosaminidases; Humans; Infant; Liver; Liver Extracts; Lysosomes; Male; Protein Deficiency; Saposins; Sphingolipid Activator Proteins

Topics: Amyotrophic Lateral Sclerosis; Chromosome Mapping; Diagnosis, Differential; G(M2) Ganglioside; Gangliosidoses; Genes, Dominant; Genes, Recessive; Genotype; Hexosaminidases; Humans; Motor Neurons; Neuromuscular Diseases; Phenotype

A 3-year-old boy developed progressive neurological deterioration in his third year, characterized by dementia, ataxia, myoclonic jerks, and bilateral macular cherry-red spots. Hexosaminidase A (HEX A) was partially decreased in the patient's serum, leukocytes, and cultured skin fibroblasts. Hexosaminidase was studied in serum and leukocytes from family members. Four members of the paternal branch appeared to be carriers of classical infantile Tay-Sachs allele, HEX alpha 2, probably receiving the gene from one great-grandparent of Ashkenazi origin. In the maternal branch, no one was a carrier of classical infantile Tay-Sachs disease, but five individuals were carriers of a milder alpha-locus defect. The patient, therefore, was a genetic compound of two different alpha-locus hexosaminidase mutations. At least 21 families with late-infantile or juvenile GM2 gangliosidosis have been reported, 18 of them with alpha-locus mutations, and three with beta-locus mutations. Genetic compounds of hexosaminidase have been reported in at least seven families, five with alpha-locus mutations and two with beta-locus mutations. The compound had the phenotype of infantile Tay-Sachs disease in one family, infantile Sandhoff disease in another, and the normal phenotype in the rest.

Topics: Child, Preschool; Chromosome Mapping; G(M2) Ganglioside; Gangliosidoses; Genetic Variation; Heterozygote; Hexosaminidases; Humans; Mutation; Pedigree; Phenotype; Tay-Sachs Disease

Total ganglioside extracts prepared from brain tissue were concentrated either by dialysis against Carbowax or by employing Millipore filter cones. Thin-layer chromatography was then carried out using silica gel plates. After location of the various fractions quantitation was effected by direct densitometry. The methods that have been adopted are rapid and suitable for the study of brain gangliosides in post mortem and biopsy material in a clinical chemistry laboratory.

Topics: Animals; Brain; Cats; Chromatography, Thin Layer; G(M1) Ganglioside; G(M2) Ganglioside; Gangliosides; Gangliosidoses; Humans; Mucopolysaccharidosis III; Tay-Sachs Disease

The physiological activator protein for the degradation of ganglioside GM2 by hexosaminidase A has been employed to assess the capability of cultured human fibroblast extracts to catalyze this ganglioside. This method permits a more reliable diagnosis of the different variants of GM2 gangliosidoses than the methods hitherto used. These either rely on artificial substrates or, when natural substrates are used, on detergents. Our method avoids a number of possible sources of error introduced by the unphysiological detergents, such as alteration of the isoenzymes' substrate specificity or inactivation of the enzymes. The range of application of the new method is discussed.

Topics: Cells, Cultured; Chemical Phenomena; Chemistry; Enzyme Activation; Fibroblasts; G(M2) Activator Protein; G(M2) Ganglioside; Gangliosides; Gangliosidoses; Glycoproteins; Hexosaminidases; Humans; Methods; Proteins; Saposins; Sphingolipid Activator Proteins; Taurodeoxycholic Acid

Human kidney extracts heated to 60 degrees and devoid of hexosaminidase activity (2-acetamido-2-deoxy-beta-D-glucoside acetamidodeoxyglucohydrolase EC 3.2.1.30) stimulate more than 20-fold the hexosaminidase A-catalyzed degradation of ganglioside GM2 and of glycolipid GA2, the neuronal storage compounds of GM2 gangliosidosis. The stimulating factor of this extract, which is labile at temperatures above 60 degrees, is also present in kidney extracts from patients with infantile GM2 gangliosidosis having a deficiency of hexosaminidase A (Tay-Sachs disease, variant B) and a deficiency of hexosaminidases A and B (variant 0). Evidence is presented that this factor is defective in the AB-variant of infantile GM2 gangliosidosis which is characterized by an accumulation of glycolipids GM2 and GA2 despite the fact that the degrading enzymes, hexosaminidases A and B, retain normal activity levels. Thus, variant AB is an example of a fatal lipid storage disease that is caused not by a defect of a degrading enzyme but rather by a defective factor necessary for the interaction of lipid substrates and the water-soluble hydrolase.

Topics: Enzyme Activation; G(M2) Ganglioside; Gangliosides; Gangliosidoses; Glycolipids; Hexosaminidases; Hot Temperature; Humans; Liver

Topics: Animals; Child, Preschool; Dendrites; G(M2) Ganglioside; Gangliosidoses; Humans; Infant; Pyramidal Tracts

Topics: Animals; Ataxia; Cerebral Cortex; Chromatography, Thin Layer; G(M1) Ganglioside; G(M2) Ganglioside; Gangliosides; Gangliosidoses; Heterozygote; Hexosaminidases; Humans; Leukocytes; Swine; Swine Diseases

Ganglioside GM2 and its asialo-derivative, GA2 were radiolabeled in their N-acetyl-D-galactosaminyl moieties by oxidation with galactose oxidase and reduction with tritiated sodium borohydride. Specific activities of 6 X 10(4) dpm/nmol (GM2) and 1.8 X 10(6) dpm/nmol (GA2) were achieved. About 98% of the label was in N-acetyl-D-galactosamine. Using these substrates, an assay was developed for GM2-N-acetyl-beta-D-galactosaminidase (E.C.3.2.1.30) and GA2-N-acetyl-beta-D-galactosaminidase (E.C.3.2.1.30) activities in human cultured skin fibroblasts. The products of the GM2 cleaving reaction were identified as N-acetylgalactosamine and ganglioside GM3. Both GM2 and GA2 cleaving activities were stimulated about 5-fold by purified sodium taurocholate, and this stimulation was inhibited by neutral detergents, lipids and albumin at low concentrations. Addition of various salts, reducing agents and a protein activator factor from human liver of Li et al. (1973) did not stimulate GM2-N-acetyl-beta-D-galactosaminidase activity beyond that found with sodium taurocholate. Under optimal conditions, control fibroblast supernates cleaved ganglioside GM2 at a rate of 3.7 nmol/mg protein/h compared to 1100 for GA2-N-acetyl-beta-D-galactosaminidase and 4700 for 4-methylumbelliferyl-N-acetyl-beta-D-glucosaminidase. Supernates from two patients with Tay-Sachs disease had markedly reduced activity levels for GM2-N-acetyl-beta-D-galactosaminidase but not for the other two substrates. Supernates from two patients with Sandhoff's disease had reduced activities for all three substrates. A supernate from one patient with juvenile GM2 gangliosidosis cleaved GM2 at a somewhat faster rate than those from Tay-Sachs or Sandhoff's patients. Two healthy adult women with markedly reduced hexosaminidase A activities using 4MU-N-acetyl-beta-D-glucosaminide as substrate had approximately half-normal activities using GM2 as substrate. A patient with the Tay-Sachs phenotype but with a partial deficiency of hexosaminidase A using the 4-MU substrate had a profound deficiency using GM2 as substrate. In such unusual hexosaminidase mutants, assays using GM2 as substrate are better indicators of phenotype than those using synthetic substrates.

Topics: Adult; Albumins; Borohydrides; Cells, Cultured; Chromatography, Thin Layer; Detergents; Female; Fibroblasts; G(M2) Ganglioside; Galactose Oxidase; Gangliosides; Gangliosidoses; Hexosaminidases; Humans; Hydrogen-Ion Concentration; Isotope Labeling; Lipidoses; Lipids; Skin; Taurocholic Acid

Two kitteens with progressive neurologic disease had increased concentrations of GM2 ganglioside in their cerebral cortex. Examination under the light microscope revealed cytoplasmic vacuolation of neurons and hepatocytes. Transmission and scanning electron microscopy demosntrated cytoplasmic inclusions encompassed by membranes in various central nervous system cell types and in hepatocytes. Beta-D-N-acetyl-hexosaminidase activity was reduced to about 1.0 percent of normal in brain, liver, and cultured skin fibroblasts of the diseased kittens; both major electrophoretic forms, A and B, of the enzyme were deficient. In fibroblasts from the parents of the diseased kittens, this enzyme activity was intermediate between that of affected and normal cats, suggesting an autosomal recessive mode of inheritance of the enzyme defect. Histopahtological and ultrastructural lesions, glycolipid storage, enzyme defect, and pattern of inheritance are similar to those of human GM2 gangliosidosis type 2.

Topics: Animals; Brain; Cat Diseases; Cats; Female; Fibroblasts; G(M2) Ganglioside; Galactosidases; Gangliosidoses; Genes, Recessive; Hexosaminidases; Humans; Kupffer Cells; Liver; Male; Neurons; Pedigree

Topics: G(M2) Ganglioside; Gangliosides; Gangliosidoses; Humans; Infant; Male; Sialic Acids

Topics: alpha-L-Fucosidase; Brain; Cells, Cultured; Fibroblasts; G(M1) Ganglioside; G(M2) Ganglioside; Gangliosidoses; Glycoproteins; Glycosphingolipids; Humans; Lipid Metabolism, Inborn Errors; Liver; Mannosidases

Two adult Ashkenazi Jewish siblings have had slowly progressive deterioration of gait and posture since early childhood, distal to proximal muscle atrophy, pes cavus, foot drop, spasticity, mild ataxia of limbs and trunk, dystonic features, and dysarthria. Vision and optic fundi are normal, verbal intelligence is stable, and no seizures have occurred. The sister of the patients died at 16 years of age with the same illness. Autopsy showed diffuse neuronal storage, predominating in subcortical areas, consisting of membranocytoplasmic bodies, zebra bodies, and complex lamellar structures. GM2 ganglioside was increased in her brain. Hexosaminidase A was decreased in serum and leukocytes of the living patients, and was in the range for carriers of Tay-Sachs disease in their parents. The disease found in this family represents a new, more indolent variant of GM2 gangliosidosis.

Topics: Adult; Brain Chemistry; Cerebellar Cortex; Cerebellum; Female; G(M2) Ganglioside; Gangliosidoses; Hexosaminidases; Humans; Inclusion Bodies; Jews; Male; Motor Cortex; Neurons; Pancreas; Pedigree; Sialic Acids; Spinal Cord; Substantia Nigra

Topics: Animals; Cytoplasmic Granules; Disease Models, Animal; G(M2) Ganglioside; Gangliosidoses; Hexosaminidases; Humans; Swine; Swine Diseases

Topics: Child, Preschool; G(M2) Ganglioside; Gangliosides; Gangliosidoses; Humans; Infant; Lipidoses; Male

Golgi and electron microscope studies of cortical neurons in several lysosomal storage diseases were carried out to elucidate structural features of the large neural processes (meganeurites) that develop as storage sites for accumulated undigestible substrates. Meganeurites occur preferentially in pyramidal neurons wherein they develop between the base of the perikaryon and the initial portion of the axon. They frequently give rise to secondary neurites which bear filopodium-like processes. Meganeurites may possess spines some of which are contacted by presynaptic processes containing synaptic vesicles. The extent of meganeurite development is related to the onset, severity and clinical course of neuronal storage disease. Extensive development of bizarre and pleomorphic meganeurites occurs in classical Tay-Sachs disease (infantile GM2-gangliosidosis, B variant), whereas a smaller proportion of neurons exhibits meganeurites in juvenile GM2-hangliosidosis and Hurler's disease. Meganeurites with spines and spine synapses were prominent in GM2-gangliosidosis, AB variant. It is proposed that meganeurites and meganeurite synapses contribute to the onset and progression of neuronal dysfunction in storage diseases by altering electrical properties of the neuron and modifying integrative operations of somadendritic synaptic inputs.

Topics: Adolescent; Biopsy; Brain; Ceroid; Child; G(M2) Ganglioside; Gangliosidoses; Humans; Infant; Lipid Metabolism, Inborn Errors; Lipidoses; Lipofuscin; Male; Mucopolysaccharidosis I; Neurons; Pyramidal Tracts; Synapses

With a view to the biochemical detection of homo- and heterozygous carriers of GM2-gangliosidosis, serum hexosaminidase activities were investigated in patients from Tay-Sachs and from Sandhoff disease, respectively, in their relatives, and in normal controls. Two related methods for the differential determination of hexosaminidase A and B activities were tested. Homozygous carriers (patients) were detected by both methods in a similar manner. As regards the identification of heterozygous carriers more conclusive results were attained by the "heat inactivation method" (O'Brien, J.S., Okada, S., Chen, A. and Fillerup, D.L. (1970) New Engl. J. Med 283, 15).

Topics: Diagnosis, Differential; G(M2) Ganglioside; Gangliosidoses; Genes; Heterozygote; Hexosaminidases; Homozygote; Humans; Lipidoses

Topics: Child, Preschool; Female; G(M2) Ganglioside; Gangliosides; Gangliosidoses; Humans; Infant; Macula Lutea; Psychomotor Disorders

Clinical and neuropathological studies of a case of AB variant GM2-gangliosidosis have been presented. The patient was a 14 months old black female infant who had "black cherry spot" in the retinas. The total activities of beta-galactosidase and N-acetyl-beta-hexosaminidase, as well as the proportion of hexosaminidase A and B components in her serum and leukocytes were normal when the assays were carried out with artificial fluorogenic substrate. Diagnosis of GM2-gangliosidosis AB variant was established by an abnormal increase of GM2-ganglioside in the biopsied brain tissue, similar to classical Tay-Sachs disease. Her clinical manifestation appeared to be similar but somewhat milder than those of classical Tay-Sachs disease. Light microscopic features of the cerebral biopsy were also closely similar to Tay-Sachs disease and Sandhoff disease but gliosis and neuronal loss were less pronounced. Electron microscopic study revealed numerous membranous cytoplasmic bodies (MCB) and zebra bodies in neurons. In addition, varieties of large intracytoplasmic inclusions in astrocytes, a feature distinctly different from classical Tay-Sachs disease, were observed. Numerous cytoplasmic inclusions were also present in oligodendroglia, pericytes and microglial cells.

Topics: Acetylglucosaminidase; Acid Phosphatase; Astrocytes; Brain Chemistry; Capillaries; Cerebral Cortex; Female; G(M2) Ganglioside; Galactosidases; Gangliosidoses; Humans; Inclusion Bodies; Infant; Lipidoses; Neuroglia; Neurons