ubiquinone and Cerebellar-Ataxia

Mutations in AarF domain-containing kinase 3 (ADCK3) are responsible for the most frequent form of hereditary coenzyme Q10 (CoQ10) deficiency (Q10 deficiency-4), which is mainly associated with autosomal recessive cerebellar ataxia type 2 (ARCA2). Clinical presentation is characterized by a variable degree of cerebellar atrophy and a broad spectrum of associated symptoms, including muscular involvement, movement disorders, neurosensory loss, cognitive impairment, psychiatric symptoms and epilepsy. In this report, we describe, for the first time, a case of photoparoxysmal response in a female patient with a mutation in ADCK3. Disease onset occurred in early childhood with gait ataxia, and mild-to-moderate degeneration. Seizures appeared at eight years and six months, occurring only during sleep. Photoparoxysmal response was observed at 14 years, almost concomitant with the genetic diagnosis (c.901C>T;c.589-3C>G) and the start of CoQ10 oral supplementation. A year later, disease progression slowed down, and photosensitivity was attenuated. A review of the literature is provided focusing on epileptic features of ADCK3-related disease as well as the physiopathology of photoparoxysmal response and supposed cerebellar involvement in photosensitivity. Moreover, the potential role of CoQ10 oral supplementation is discussed. Prospective studies on larger populations are needed to further understand these data.

Topics: Adolescent; Cerebellar Ataxia; Epilepsy, Reflex; Female; Humans; Magnetic Resonance Imaging; Mitochondrial Proteins; Ubiquinone

Coenzyme Q (CoQ) is a component of the electron transport chain that participates in aerobic cellular respiration to produce ATP. In addition, CoQ acts as an electron acceptor in several enzymatic reactions involving oxidation-reduction. Biosynthesis of CoQ has been investigated mainly in Escherichia coli and Saccharomyces cerevisiae, and the findings have been extended to various higher organisms, including plants and humans. Analyses in yeast have contributed greatly to current understanding of human diseases related to CoQ biosynthesis. To date, human genetic disorders related to mutations in eight COQ biosynthetic genes have been reported. In addition, the crystal structures of a number of proteins involved in CoQ synthesis have been solved, including those of IspB, UbiA, UbiD, UbiX, UbiI, Alr8543 (Coq4 homolog), Coq5, ADCK3, and COQ9. Over the last decade, knowledge of CoQ biosynthesis has accumulated, and striking advances in related human genetic disorders and the crystal structure of proteins required for CoQ synthesis have been made. This review focuses on the biosynthesis of CoQ in eukaryotes, with some comparisons to the process in prokaryotes.

Topics: Adenosine Triphosphate; Cerebellar Ataxia; Electron Transport; Electron Transport Chain Complex Proteins; Escherichia coli; Gene Expression Regulation; Humans; Methyltransferases; Mitochondrial Encephalomyopathies; Mitochondrial Proteins; Mixed Function Oxygenases; Oxidation-Reduction; Plants; Saccharomyces cerevisiae; Ubiquinone

Chronic ataxias are an heterogeneous group of disorders that affect the child at different ages. Thus, the congenital forms, generally non progressive are observed from first months of life and are expressed by hypotonia and motor delay long before the ataxia became evident. The cerebral magnetic resonance images (MRI) may be diagnostic in some pictures like Joubert syndrome. The group of progressive hereditary ataxias, usually begin after the infant period. The clinical signs are gait instability and ocular apraxia that can be associated with oculocutaneous telangiectasias (ataxia-telangiesctasia) or with sensory neuropathy (Friedreich ataxia). In this review are briefly described congenital ataxias and in more detailed form the progressive hereditary ataxias autosomal recessive, autosomal dominants and mitochondrials. The importance of genetic study is emphasized, because it is the key to obtain the diagnosis in the majority of these diseases. Although now there are no treatments for the majority of progressive hereditary ataxias, some they have like Refsum disease, vitamine E deficiency, Coenzyme Q10 deficiency and others, thus the diagnosis in these cases is even more important. At present the diagnosis of childhood hereditary ataxia not yet treatable is fundamental to obtain suitable handling, determine a precise outcome and to give to the family an opportune genetic counseling.

Topics: Ataxia; Cerebellar Ataxia; Child; Chronic Disease; Female; Humans; Male; Mitochondrial Diseases; Muscle Weakness; Spinocerebellar Degenerations; Ubiquinone

Autosomal recessive cerebellar ataxias belong to a broader group of disorders known as inherited ataxias. In most cases onset occurs before the age of 20. These neurological disorders are characterized by degeneration or abnormal development of the cerebellum and spinal cord. Currently, specific treatment is only available for some of the chronic ataxias, more specifically those related to a known metabolic defect, such as abetalipoproteinemia, ataxia with vitamin E deficiency, and cerebrotendinous xanthomatosis. Treatment based on a diet with reduced intake of fat, supplementation of oral vitamins E and A, and the administration of chenodeoxycholic acid could modify the course of the disease. Although for most of autosomal recessive ataxias there is no definitive treatment, iron chelators and antioxidants have been proposed to reduce the mitochondrial iron overload in Friederich's ataxia patients. Corticosteroids have been used to reduce ataxia symptoms in ataxia telangiectasia. Coenzyme Q10 deficiency associated with ataxia may be responsive to Co Q10 or ubidecarenone supplementations. Early treatment of these disorders may be associated with a better drug response.

Topics: Adrenal Cortex Hormones; Ataxia; Cerebellar Ataxia; Chronic Disease; Frataxin; Friedreich Ataxia; Humans; Iron-Binding Proteins; Mitochondrial Diseases; Muscle Weakness; Ubiquinone; Vitamin E; Vitamin E Deficiency

Coenzyme Q(10) (CoQ(10)) deficiency has been associated with 5 major clinical phenotypes: encephalomyopathy, severe infantile multisystemic disease, nephropathy, cerebellar ataxia, and isolated myopathy. Primary CoQ(10) deficiency is due to defects in CoQ(10) biosynthesis, while secondary forms are due to other causes. A review of 149 cases, including our cohort of 76 patients, confirms that CoQ(10) deficiency is a clinically and genetically heterogeneous syndrome that mainly begins in childhood and predominantly manifests as cerebellar ataxia. Coenzyme Q(10) measurement in muscle is the gold standard for diagnosis. Identification of CoQ(10) deficiency is important because the condition frequently responds to treatment. Causative mutations have been identified in a small proportion of patients.

Topics: Animals; Cerebellar Ataxia; Cohort Studies; Genetic Heterogeneity; Humans; Ubiquinone

Deficiency of Coenzyme Q10 (CoQ10) in muscle has been associated with a spectrum of diseases including infantile-onset multi-systemic diseases, encephalomyopathies with recurrent myobinuria, cerebellar ataxia, and pure myopathy. CoQ10 deficiency predominantly affects children, but patients have presented with adult-onset cerebellar ataxia or myopathy. Mutations in the CoQ10 biosynthetic genes, COQ2 and PDSS2, have been identified in children with the infantile form of CoQ10 deficiency; however, the molecular genetic bases of adult-onset CoQ10 deficiency remains undefined.

Topics: Adult; Cerebellar Ataxia; Electron Transport; Female; Humans; Male; Middle Aged; Mitochondrial Encephalomyopathies; Models, Biological; Models, Chemical; Muscle, Skeletal; Muscles; Muscular Diseases; Ubiquinone

Coenzyme Q(10) (CoQ) deficiency is an autosomal recessive disorder presenting five phenotypes: a myopathic form, a severe infantile neurological syndrome associated with nephritic syndrome, an ataxic variant, Leigh syndrome and a pure myopathic form. The third is the most common phenotype related with CoQ deficiency and it will be the focus of this review. This new syndrome presents muscle CoQ deficiency associated with cerebellar ataxia and cerebellar atrophy as the main neurological signs. Biochemically, the hallmark of CoQ deficiency syndrome is a decreased CoQ concentration in muscle and/or fibroblasts. There is no molecular evidence of the enzyme or gene involved in primary CoQ deficiencies associated with cerebellar ataxia, although recently a family has been reported with mutations at COQ2 gene who present a distinct phenotype. Patients with primary CoQ deficiency may benefit from CoQ supplementation, although the clinical response to this therapy varies even among patients with similar phenotypes. Some present an excellent response to CoQ while others show only a partial improvement of some symptoms and signs. CoQ deficiency is the mitochondrial encephalomyopathy with the best clinical response to CoQ supplementation, highlighting the importance of an early identification of this disorder.

Topics: Alkyl and Aryl Transferases; Atrophy; Cerebellar Ataxia; Cerebellum; Coenzymes; Genetic Predisposition to Disease; Humans; Mitochondria; Mitochondrial Diseases; Ubiquinone

Primary coenzyme Q10 (CoQ10) deficiency, a recessive disorder associated with various defects of CoQ10 biosynthesis and widely varying clinical presentation, is customarily managed by oral Q10 supplementation but the benefit is debated.. To address this question, we mapped individual responses in two patients with COQ8A-related ataxia following coenzyme Q10 supplementation using noninvasive imaging. Metabolic. Post-treatment change in energy metabolite levels differed in the two patients, with higher energy levels and improved dysarthria and leg coordination in one, and decreased energy levels without clinical benefit in the other.. Our results suggest that the cerebellar bioenergetic state may predict treatment response in COQ8A-related ataxia and highlight the potential of pathophysiology-orientated neuroimaging evidence to inform treatment decisions.

Topics: Ataxia; Cerebellar Ataxia; Energy Metabolism; Humans; Mitochondrial Diseases; Muscle Weakness; Ubiquinone

COQ4 codes for a mitochondrial protein required for coenzyme Q. In-house exome and genome datasets (n = 14,303) were screened for patients with bi-allelic variants in COQ4. Work-up included clinical characterization and functional studies in patient-derived cell lines.. Six different COQ4 variants, three of them novel, were identified in six adult patients from four different families. Three patients had a phenotype of hereditary spastic paraparesis, two sisters showed a predominant cerebellar ataxia, and one patient had mild signs of both. Studies in patient-derived fibroblast lines revealed significantly reduced amounts of COQ4 protein, decreased CoQ. We report bi-allelic variants in COQ4 causing an adult-onset ataxia-spasticity spectrum phenotype and a disease course much milder than previously reported. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Topics: Ataxia; Cerebellar Ataxia; Humans; Mitochondrial Diseases; Mitochondrial Proteins; Muscle Spasticity; Muscle Weakness; Mutation; Ubiquinone

The spectrum of coenzyme Q

Topics: Adult; Ataxia; Cerebellar Ataxia; Dystonic Disorders; Female; Homozygote; Humans; Mitochondrial Proteins; Mutation; Ubiquinone

To foster trial-readiness of coenzyme Q8A (COQ8A)-ataxia, we map the clinicogenetic, molecular, and neuroimaging spectrum of COQ8A-ataxia in a large worldwide cohort, and provide first progression data, including treatment response to coenzyme Q10 (CoQ10).. Cross-modal analysis of a multicenter cohort of 59 COQ8A patients, including genotype-phenotype correlations, 3D-protein modeling, in vitro mutation analyses, magnetic resonance imaging (MRI) markers, disease progression, and CoQ10 response data.. Fifty-nine patients (39 novel) with 44 pathogenic COQ8A variants (18 novel) were identified. Missense variants demonstrated a pleiotropic range of detrimental effects upon protein modeling and in vitro analysis of purified variants. COQ8A-ataxia presented as variable multisystemic, early-onset cerebellar ataxia, with complicating features ranging from epilepsy (32%) and cognitive impairment (49%) to exercise intolerance (25%) and hyperkinetic movement disorders (41%), including dystonia and myoclonus as presenting symptoms. Multisystemic involvement was more prevalent in missense than biallelic loss-of-function variants (82-93% vs 53%; p = 0.029). Cerebellar atrophy was universal on MRI (100%), with cerebral atrophy or dentate and pontine T2 hyperintensities observed in 28%. Cross-sectional (n = 34) and longitudinal (n = 7) assessments consistently indicated mild-to-moderate progression of ataxia (SARA: 0.45/year). CoQ10 treatment led to improvement by clinical report in 14 of 30 patients, and by quantitative longitudinal assessments in 8 of 11 patients (SARA: -0.81/year). Explorative sample size calculations indicate that ≥48 patients per arm may suffice to demonstrate efficacy for interventions that reduce progression by 50%.. This study provides a deeper understanding of the disease, and paves the way toward large-scale natural history studies and treatment trials in COQ8A-ataxia. ANN NEUROL 2020;88:251-263.

Topics: Adolescent; Adult; Aged; Cerebellar Ataxia; Child; Child, Preschool; Cohort Studies; Cross-Sectional Studies; Female; Genetic Variation; Humans; Magnetic Resonance Imaging; Male; Middle Aged; Mutation; Protein Structure, Secondary; Ubiquinone; Young Adult

Topics: Adult; Cerebellar Ataxia; Fibroblasts; Humans; Male; Mitochondria; Mitochondrial Diseases; Mitochondrial Proteins; Muscle, Skeletal; Mutation; Ubiquinone

Primary deficiency of coenzyme Q10 (CoQ10 ubiquinone), is classified as a mitochondrial respiratory chain disorder with phenotypic variability. The clinical manifestation may involve one or multiple tissue with variable severity and presentation may range from infancy to late onset. ADCK3 gene mutations are responsible for the most frequent form of hereditary CoQ10 deficiency (Q10 deficiency-4 OMIM #612016) which is mainly associated with autosomal recessive spinocerebellar ataxia (ARCA2, SCAR9). Here we provide the clinical, biochemical and genetic investigation for unrelated three nuclear families presenting an autosomal form of Spino-Cerebellar Ataxia due to novel mutations in the ADCK3 gene. Using next generation sequence technology we identified a homozygous Gln343Ter mutation in one family with severe, early onset of the disease and compound heterozygous mutations of Gln343Ter and Ser608Phe in two other families with variable manifestations. Biochemical investigation in fibroblasts showed decreased activity of the CoQ dependent mitochondrial respiratory chain enzyme succinate cytochrome c reductase (complex II + III). Exogenous CoQ slightly improved enzymatic activity, ATP production and decreased oxygen free radicals in some of the patient's cells. Our results are presented in comparison to previously reported mutations and expanding the clinical, molecular and biochemical spectrum of ADCK3 related CoQ10 deficiencies.

Topics: Ataxia; Cerebellar Ataxia; Child, Preschool; Female; Fibroblasts; Humans; Infant; Male; Mitochondria; Mitochondrial Diseases; Mitochondrial Proteins; Muscle Weakness; Mutation; Ubiquinone

Primary coenzyme Q10 (CoQ

Topics: Biopsy; Biosynthetic Pathways; Cerebellar Ataxia; Dietary Supplements; DNA Copy Number Variations; Electron Transport; Female; Fibroblasts; Genetic Association Studies; High-Throughput Nucleotide Sequencing; Humans; Leukocytes; Methyltransferases; Mitochondrial Encephalomyopathies; Mitochondrial Proteins; Muscles; Oxygen Consumption; Pedigree; Polymorphism, Single Nucleotide; Siblings; Ubiquinone

Inherited ataxias are a group of heterogeneous disorders in children or adults but their genetic definition remains still undetermined in almost half of the patients. However, CoQ10 deficiency is a rare cause of cerebellar ataxia and ADCK3 is the most frequent gene associated with this defect. We herein report a 48 year old man, who presented with dysarthria and walking difficulties. Brain magnetic resonance imaging showed a marked cerebellar atrophy. Serum lactate was elevated. Tissues obtained by muscle and skin biopsies were studied for biochemical and genetic characterization. Skeletal muscle biochemistry revealed decreased activities of complexes I+III and II+III and a severe reduction of CoQ10 , while skin fibroblasts showed normal CoQ10 levels. A mild loss of maximal respiration capacity was also found by high-resolution respirometry. Molecular studies identified a novel homozygous deletion (c.504del_CT) in ADCK3, causing a premature stop codon. Western blot analysis revealed marked reduction of ADCK3 protein levels. Treatment with CoQ10 was started and, after 1 year follow-up, patient neurological condition slightly improved. This report suggests the importance of investigating mitochondrial function and, in particular, muscle CoQ10 levels, in patients with adult-onset cerebellar ataxia. Moreover, clinical stabilization by CoQ10 supplementation emphasizes the importance of an early diagnosis.

Topics: Ataxia; Cerebellar Ataxia; Codon, Nonsense; Delayed Diagnosis; Electron Transport Chain Complex Proteins; Fibroblasts; Gene Expression; Homozygote; Humans; Lactic Acid; Magnetic Resonance Imaging; Male; Middle Aged; Mitochondria; Mitochondrial Diseases; Mitochondrial Proteins; Muscle Weakness; Muscle, Skeletal; Skin; Ubiquinone

Defects of coenzyme Q10 (CoQ10) metabolism cause a variety of disorders ranging from isolated myopathy to multisystem involvement. ADCK3 is one of several genes associated with CoQ10 deficiency that presents with progressive cerebellar ataxia, epilepsy, migraine and psychiatric disorders. Diagnosis is challenging due to the wide clinical spectrum and overlap with other mitochondrial disorders.. A detailed description of three new patients and one previously reported patient from three Norwegian families with novel and known ADCK3 mutations is provided focusing on the epileptic semiology and response to treatment. Mutations were identified by whole exome sequencing and in two measurement of skeletal muscle CoQ10 was performed.. All four patients presented with childhood-onset epilepsy and progressive cerebellar ataxia. Three patients had epilepsia partialis continua and stroke-like episodes affecting the posterior brain. Electroencephalography showed focal epileptic activity in the occipital and temporal lobes. Genetic investigation revealed ADCK3 mutations in all patients including a novel change in exon 15: c.T1732G, p.F578V. There was no apparent genotype-phenotype correlation.. ADCK3 mutations can cause a combination of progressive ataxia and acute epileptic encephalopathy with stroke-like episodes. The clinical, radiological and electrophysiological features of this disorder mimic the phenotype of polymerase gamma (POLG) related encephalopathy and it is therefore suggested that ADCK3 mutations be considered in the differential diagnosis of mitochondrial encephalopathy with POLG-like features.

Topics: Adult; Ataxia; Cerebellar Ataxia; Diagnosis, Differential; Epilepsy; Female; Humans; Male; Mitochondrial Diseases; Mitochondrial Encephalomyopathies; Mitochondrial Proteins; Muscle Weakness; Mutation; Phenotype; Ubiquinone; Young Adult

The UbiB protein kinase-like (PKL) family is widespread, comprising one-quarter of microbial PKLs and five human homologs, yet its biochemical activities remain obscure. COQ8A (ADCK3) is a mammalian UbiB protein associated with ubiquinone (CoQ) biosynthesis and an ataxia (ARCA2) through unclear means. We show that mice lacking COQ8A develop a slowly progressive cerebellar ataxia linked to Purkinje cell dysfunction and mild exercise intolerance, recapitulating ARCA2. Interspecies biochemical analyses show that COQ8A and yeast Coq8p specifically stabilize a CoQ biosynthesis complex through unorthodox PKL functions. Although COQ8 was predicted to be a protein kinase, we demonstrate that it lacks canonical protein kinase activity in trans. Instead, COQ8 has ATPase activity and interacts with lipid CoQ intermediates, functions that are likely conserved across all domains of life. Collectively, our results lend insight into the molecular activities of the ancient UbiB family and elucidate the biochemical underpinnings of a human disease.

Topics: Animals; Behavior, Animal; Cerebellar Ataxia; Cerebellum; Chlorocebus aethiops; COS Cells; Disease Models, Animal; Exercise Tolerance; Female; Genetic Predisposition to Disease; HEK293 Cells; Humans; Lipid Metabolism; Male; Maze Learning; Mice, Inbred C57BL; Mice, Knockout; Mitochondrial Proteins; Models, Molecular; Motor Activity; Muscle Strength; Muscle, Skeletal; Phenotype; Protein Binding; Protein Conformation; Proteomics; Recognition, Psychology; Rotarod Performance Test; Saccharomyces cerevisiae; Saccharomyces cerevisiae Proteins; Seizures; Structure-Activity Relationship; Time Factors; Transfection; Ubiquinone

The autosomal-recessive cerebellar ataxias (ARCA) are a clinically and genetically heterogeneous group of neurodegenerative disorders. The large number of ARCA genes leads to delay and difficulties obtaining an exact diagnosis in many patients and families. Ubiquinone (CoQ10) deficiency is one of the potentially treatable causes of ARCAs as some patients respond to CoQ10 supplementation. The AarF domain containing kinase 3 gene (ADCK3) is one of several genes associated with CoQ10 deficiency. ADCK3 encodes a mitochondrial protein which functions as an electron-transfer membrane protein complex in the mitochondrial respiratory chain (MRC).. We report two siblings from a consanguineous Pakistani family who presented with cerebellar ataxia and severe myoclonus from adolescence. Whole exome sequencing and biochemical assessment of fibroblasts were performed in the index patient.. A novel homozygous frameshift mutation in ADCK3 (p.Ser616Leufs*114), was identified in both siblings. This frameshift mutation results in the loss of the stop codon, extending the coding protein by 81 amino acids. Significant CoQ10 deficiency and reduced MRC enzyme activities in the index patient's fibroblasts suggested that the mutant protein may reduce the efficiency of mitochondrial electron transfer. CoQ10 supplementation was initiated following these genetic and biochemical analyses. She gained substantial improvement in myoclonic movements, ataxic gait and dysarthric speech after treatment.. This study highlights the importance of diagnosing ADCK3 mutations and the potential benefit of treatment for patients. The identification of this new mutation broadens the phenotypic spectrum associated with ADCK3 mutations and provides further understanding of their pathogenic mechanism.

Topics: Adult; Cerebellar Ataxia; Consanguinity; Female; Frameshift Mutation; Humans; Mitochondrial Proteins; Pedigree; Protein Kinases; Ubiquinone

Disorders of coenzyme Q(10) (CoQ(10)) biosynthesis represent the most treatable subgroup of mitochondrial diseases. Neurological involvement is frequently observed in CoQ(10) deficiency, typically presenting as cerebellar ataxia and/or seizures. The aetiology of the neurological presentation of CoQ(10) deficiency has yet to be fully elucidated and therefore in order to investigate these phenomena we have established a neuronal cell model of CoQ(10) deficiency by treatment of neuronal SH-SY5Y cell line with para-aminobenzoic acid (PABA). PABA is a competitive inhibitor of the CoQ(10) biosynthetic pathway enzyme, COQ2. PABA treatment (1 mM) resulted in a 54 % decrease (46 % residual CoQ(10)) decrease in neuronal CoQ(10) status (p < 0.01). Reduction of neuronal CoQ(10) status was accompanied by a progressive decrease in mitochondrial respiratory chain enzyme activities, with a 67.5 % decrease in cellular ATP production at 46 % residual CoQ(10). Mitochondrial oxidative stress increased four-fold at 77 % and 46 % residual CoQ(10). A 40 % increase in mitochondrial membrane potential was detected at 46 % residual CoQ(10) with depolarisation following oligomycin treatment suggesting a reversal of complex V activity. This neuronal cell model provides insights into the effects of CoQ(10) deficiency on neuronal mitochondrial function and oxidative stress, and will be an important tool to evaluate candidate therapies for neurological conditions associated with CoQ(10) deficiency.

Topics: 4-Aminobenzoic Acid; Adenosine Triphosphate; Ataxia; Cell Line, Tumor; Cerebellar Ataxia; DNA, Mitochondrial; Electron Transport; Energy Metabolism; Humans; Membrane Potential, Mitochondrial; Mitochondria; Mitochondrial Diseases; Mitochondrial Membranes; Mitochondrial Proton-Translocating ATPases; Muscle Weakness; Oxidative Stress; Ubiquinone

PDSS2 is a gene that encodes one of the two subunits of trans-prenyl diphosphate synthase that is essential for ubiquinone biosynthesis. It is known that mutations in PDSS2 can cause primary ubiquinone deficiency in humans and a similar disease in mice. Cerebellum is the most often affected organ in ubiquinone deficiency, and cerebellar atrophy has been diagnosed in many infants with this disease. In this study, two Pdss2 conditional knockout mouse lines directed by Pax2-cre and Pcp2-cre were generated to investigate the effect of ubiquinone deficiency on cerebellum during embryonic development and in adulthood, respectively. The Pdss2(f/-); Pax2-cre mouse recapitulates some symptoms of ubiquinone deficiency in infants, including severe cerebellum hypoplasia and lipid accumulation in skeletal muscles at birth. During early cerebellum development (E12.5-14.5), Pdss2 knockout initially causes the delay of radial glial cell growth and neuron progenitor migration, so the growth of mutant cerebellum is retarded. During later development (E15.5-P0), increased ectopic apoptosis of neuroblasts and impaired cell proliferation result in the progression of cerebellum hypoplasia in the mutant. Thus, the mutant cerebellum contains fewer neurons at birth, and the cells are disorganized. The developmental defect of mutant cerebellum does not result from reduced Fgf8 expression before E12.5. Electron microscopy reveals mitochondrial defects and increased autophagic-like vacuolization that may arise in response to abnormal mitochondria in the mutant cerebellum. Nevertheless, the mutant mice die soon after birth probably due to cleft palate and micrognathia, which may result from Pdss2 knockout caused by ectopic Pax2-cre expression in the first branchial arch. On the other hand, the Pdss2(f/-); Pcp2-cre mouse is healthy at birth but gradually loses cerebellar Purkinje cells and develops ataxia-like symptoms at 9.5 months; thus this conditional knockout mouse may serve as a model for ubiquinone deficiency in adult patients. In conclusion, this study provides two mouse models of Pdss2 based ubiquinone deficiency. During cerebellum development, Pdss2 knockout results in severe cerebellum hypoplasia by impairing cell migration and eliciting ectopic apoptosis, whereas Pdss2 knockout in Purkinje cells at postnatal stages leads to the development of cerebellar ataxia.

Topics: Alkyl and Aryl Transferases; Animals; Apoptosis; Cell Movement; Cell Proliferation; Cerebellar Ataxia; Cerebellum; Gait; Mice; Mice, Knockout; Purkinje Cells; Ubiquinone; Walking

Childhood cerebellar ataxias, and particularly congenital ataxias, are heterogeneous disorders and several remain undefined. We performed a muscle biopsy in patients with congenital ataxia and children with later onset undefined ataxia having neuroimaging evidence of cerebellar atrophy. Significant reduced levels of Coenzyme Q10 (COQ10) were found in the skeletal muscle of 9 out of 34 patients that were consecutively screened. A mutation in the ADCK3/Coq8 gene (R347X) was identified in a female patient with ataxia, seizures and markedly reduced COQ10 levels. In a 2.5-years-old male patient with non syndromic congenital ataxia and autophagic vacuoles in the muscle biopsy we identified a homozygous nonsense mutation R111X mutation in SIL1 gene, leading to early diagnosis of Marinesco-Sjogren syndrome. We think that muscle biopsy is a valuable procedure to improve diagnostic assesement in children with congenital ataxia or other undefined forms of later onset childhood ataxia associated to cerebellar atrophy at MRI.

Topics: Biopsy; Cerebellar Ataxia; Child, Preschool; Chromatography, High Pressure Liquid; DNA Mutational Analysis; Female; Guanine Nucleotide Exchange Factors; Humans; Male; Muscle, Skeletal; Mutation; Ubiquinone

Coenzyme Q10 (CoQ10 or ubiquinone) is a lipid-soluble component of virtually all cell membranes and has multiple metabolic functions. A major function of CoQ10 is to transport electrons from complexes I and II to complex III in the respiratory chain which resides in the mitochondrial inner membrane. Deficiencies of CoQ10 (MIM 607426) have been associated with four major clinical phenotypes: 1) encephalomyopathy characterized by a triad of recurrent myoglobinuria, brain involvement, and ragged-red fibers; 2) infantile multisystemic disease typically with prominent nephropathy and encephalopathy; 3) cerebellar ataxia with marked cerebellar atrophy; and 4) pure myopathy. Primary CoQ10 deficiencies due to mutations in ubiquinone biosynthetic genes (COQ2, PDSS1, PDSS2, and ADCK3 [CABC1]) have been identified in patients with the infantile multisystemic and cerebellar ataxic phenotypes. In contrast, secondary CoQ10 deficiencies, due to mutations in genes not directly related to ubiquinone biosynthesis (APTX, ETFDH, and BRAF), have been identified in patients with cerebellar ataxia, pure myopathy, and cardiofaciocutaneous syndrome. In many patients with CoQ10 deficiencies, the causative molecular genetic defects remain unknown; therefore, it is likely that mutations in additional genes will be identified as causes of CoQ10 deficiencies.

Topics: Cerebellar Ataxia; Humans; Mitochondrial Encephalomyopathies; Mitochondrial Myopathies; Syndrome; Ubiquinone

Coenzyme Q(10) (CoQ(10)) plays a pivotal role in oxidative phosphorylation (OXPHOS) in that it distributes electrons between the various dehydrogenases and the cytochrome segments of the respiratory chain. Primary coenzyme Q(10) deficiency represents a clinically heterogeneous condition suggestive of genetic heterogeneity, and several disease genes have been previously identified. The CABC1 gene, also called COQ8 or ADCK3, is the human homolog of the yeast ABC1/COQ8 gene, one of the numerous genes involved in the ubiquinone biosynthesis pathway. The exact function of the Abc1/Coq8 protein is as yet unknown, but this protein is classified as a putative protein kinase. We report here CABC1 gene mutations in four ubiquinone-deficient patients in three distinct families. These patients presented a similar progressive neurological disorder with cerebellar atrophy and seizures. In all cases, enzymological studies pointed to ubiquinone deficiency. CoQ(10) deficiency was confirmed by decreased content of ubiquinone in muscle. Various missense mutations (R213W, G272V, G272D, and E551K) modifying highly conserved amino acids of the protein and a 1 bp frameshift insertion c.[1812_1813insG] were identified. The missense mutations were introduced into the yeast ABC1/COQ8 gene and expressed in a Saccharomyces cerevisiae strain in which the ABC1/COQ8 gene was deleted. All the missense mutations resulted in a respiratory phenotype with no or decreased growth on glycerol medium and a severe reduction in ubiquinone synthesis, demonstrating that these mutations alter the protein function.

Topics: Adolescent; Adult; Amino Acid Sequence; Benzoquinones; Brain; Cerebellar Ataxia; Female; Haplotypes; Humans; Magnetic Resonance Imaging; Male; Molecular Sequence Data; Muscle, Skeletal; Mutation, Missense; Pedigree; Seizures; Ubiquinone

Muscle coenzyme Q(10) (CoQ(10) or ubiquinone) deficiency has been identified in more than 20 patients with presumed autosomal-recessive ataxia. However, mutations in genes required for CoQ(10) biosynthetic pathway have been identified only in patients with infantile-onset multisystemic diseases or isolated nephropathy. Our SNP-based genome-wide scan in a large consanguineous family revealed a locus for autosomal-recessive ataxia at chromosome 1q41. The causative mutation is a homozygous splice-site mutation in the aarF-domain-containing kinase 3 gene (ADCK3). Five additional mutations in ADCK3 were found in three patients with sporadic ataxia, including one known to have CoQ(10) deficiency in muscle. All of the patients have childhood-onset cerebellar ataxia with slow progression, and three of six have mildly elevated lactate levels. ADCK3 is a mitochondrial protein homologous to the yeast COQ8 and the bacterial UbiB proteins, which are required for CoQ biosynthesis. Three out of four patients tested showed a low endogenous pool of CoQ(10) in their fibroblasts or lymphoblasts, and two out of three patients showed impaired ubiquinone synthesis, strongly suggesting that ADCK3 is also involved in CoQ(10) biosynthesis. The deleterious nature of the three identified missense changes was confirmed by the introduction of them at the corresponding positions of the yeast COQ8 gene. Finally, a phylogenetic analysis shows that ADCK3 belongs to the family of atypical kinases, which includes phosphoinositide and choline kinases, suggesting that ADCK3 plays an indirect regulatory role in ubiquinone biosynthesis possibly as part of a feedback loop that regulates ATP production.

Topics: Amino Acid Sequence; Brain; Cerebellar Ataxia; Coenzymes; Female; Genes, Recessive; Humans; Magnetic Resonance Imaging; Male; Molecular Sequence Data; Mutation; Pedigree; Phosphotransferases; Sequence Analysis, DNA; Ubiquinone; Yeasts

Our aim was to report a new case with cerebellar ataxia associated with coenzyme Q10 (CoQ) deficiency, the biochemical findings caused by this deficiency and the response to CoQ supplementation.. A 12-year-old girl presenting ataxia and cerebellar atrophy. BIOCHEMICAL STUDIES: Coenzyme Q10 in muscle was analysed by HPLC with electrochemical detection and mitochondrial respiratory chain (MRC) enzyme activities by spectrophotometric methods. CoQ biosynthesis in fibroblasts was assayed by studying the incorporation of radiolabeled 4-hydroxy[U 14C] benzoic acid by HPLC with radiometric detection.. Mitochondrial respiratory chain enzyme analysis showed a decrease in complex I + III and complex II + III activities. CoQ concentration in muscle was decreased (56 nmol/g of protein: reference values: 157-488 nmol/g protein). A reduced incorporation of radiolabeled 4-hydroxy[U- 14C] benzoic acid was observed in the patient (19% of incorporation respect to the median control values). After 16 months of CoQ supplementation, the patient is now able to walk unaided and cerebellar signs have disappeared.. Cerebellar ataxia associated with CoQ deficiency in our case might be allocated in the transprenylation pathway or in the metabolic steps after condensation of 4-hydroxybenzoate and the prenyl side chain of CoQ. Clinical improvement after CoQ supplementation was remarkable, supporting the importance of an early diagnosis of this kind of disorders.

Topics: Antioxidants; Cerebellar Ataxia; Child; Chromatography, High Pressure Liquid; Coenzymes; Dietary Supplements; Electrochemistry; Female; Fibroblasts; Humans; Immunohistochemistry; Magnetic Resonance Imaging; Mitochondria, Muscle; Muscle, Skeletal; Neurologic Examination; Ubiquinone

Two brothers had late-onset progressive ataxia, cerebellar atrophy, and hypergonadotropic hypogonadism associated with coenzyme Q10 (CoQ10) deficiency in skeletal muscle. Both patients improved on high-dose CoQ10 supplementation, stressing the importance of CoQ10 deficiency in the differential diagnosis of cerebellar ataxia, even when onset is late.

Topics: Adult; Age of Onset; Cerebellar Ataxia; Coenzymes; Diagnosis, Differential; Humans; Hypogonadism; Male; Middle Aged; Mitochondrial Encephalomyopathies; Muscle, Skeletal; Siblings; Ubiquinone

The authors report 7 years of follow-up evaluation of a patient with coenzyme Q10 (CoQ10) deficiency. Initial symptoms of exercise intolerance and hyperlactatemia improved markedly with substitutive treatment. However, CoQ(10) supplementation did not prevent the onset of a cerebellar syndrome. A switch to idebenone treatment resulted in clinical and metabolic worsening, which disappeared with subsequent CoQ10 treatment. CoQ10 defects may cause progressive neurologic disease despite supplementation.

Topics: Benzoquinones; Carnitine; Cerebellar Ataxia; Cerebellum; Child, Preschool; Disease Progression; Drug Therapy, Combination; Exercise Tolerance; Female; Follow-Up Studies; Humans; Lactates; Magnetic Resonance Imaging; Mitochondria, Muscle; Mitochondrial Myopathies; Muscle, Skeletal; Treatment Failure; Ubiquinone; Vomiting

The authors measured coenzyme Q10 (CoQ10) concentration in muscle biopsies from 135 patients with genetically undefined cerebellar ataxia. Thirteen patients with childhood-onset ataxia and cerebellar atrophy had markedly decreased levels of CoQ10. Associated symptoms included seizures, developmental delay, mental retardation, and pyramidal signs. These findings confirm the existence of an ataxic presentation of CoQ10 deficiency, which may be responsive to CoQ10 supplementation.

Topics: Adolescent; Adult; Cerebellar Ataxia; Cerebellum; Child; Coenzymes; Developmental Disabilities; Dietary Supplements; Disease Progression; Electromyography; Electron Transport; Female; Humans; Magnetic Resonance Imaging; Male; Mitochondria; Muscle Hypotonia; Muscle, Skeletal; Seizures; Ubiquinone

Our findings in 19 new patients with cerebellar ataxia establish the existence of an ataxic syndrome due to primary CoQ10 deficiency and responsive to CoQ10 therapy. As all patients presented cerebellar ataxia and cerebellar atrophy, this suggests a selective vulnerability of the cerebellum to CoQ10 deficiency. We investigated the regional distribution of coenzyme Q10 in the brain of adult rats and in the brain of one human subject. We also evaluated the levels of coenzyme Q9 (CoQ9) and CoQ10 in different brain regions and in visceral tissues of rats before and after oral administration of CoQ10. Our results show that in rats, amongst the seven brain regions studied, cerebellum contains the lowest level of CoQ. However, the relative proportion of CoQ10 was the same (about 30% of total CoQ) in all regions studied. The level of CoQ10 is much higher in brain than in blood or visceral tissue, such as liver, heart, or kidney. Daily oral administration of CoQ10 led to substantial increases of CoQ10 concentrations only in blood and liver. Of the four regions of one human brain studied, cerebellum again had the lowest CoQ10y concentration.

Topics: Animals; Brain Chemistry; Brain Diseases; Cerebellar Ataxia; Cerebellum; Cerebral Cortex; Coenzymes; Corpus Striatum; Humans; Kidney; Liver; Myocardium; Rats; Rats, Sprague-Dawley; Tissue Distribution; Ubiquinone

To describe a clinical syndrome of cerebellar ataxia associated with muscle coenzyme Q10 (CoQ10) deficiency.. Muscle CoQ10 deficiency has been reported only in a few patients with a mitochondrial encephalomyopathy characterized by 1) recurrent myoglobinuria; 2) brain involvement (seizures, ataxia, mental retardation), and 3) ragged-red fibers and lipid storage in the muscle biopsy.. Having found decreased CoQ10 levels in muscle from a patient with unclassified familial cerebellar ataxia, the authors measured CoQ10 in muscle biopsies from other patients in whom cerebellar ataxia could not be attributed to known genetic causes.. The authors found muscle CoQ10 deficiency (26 to 35% of normal) in six patients with cerebellar ataxia, pyramidal signs, and seizures. All six patients responded to CoQ10 supplementation; strength increased, ataxia improved, and seizures became less frequent.. Primary CoQ10 deficiency is a potentially important cause of familial ataxia and should be considered in the differential diagnosis of this condition because CoQ10 administration seems to improve the clinical picture.

Topics: Adolescent; Adult; Brain; Cerebellar Ataxia; Child; Electron Transport Complex III; Female; Humans; Magnetic Resonance Imaging; Male; Muscles; Seizures; Ubiquinone

We report severe coenzyme Q10 deficiency of muscle in a 4-year-old boy presenting with progressive muscle weakness, seizures, cerebellar syndrome, and a raised cerebro-spinal fluid lactate concentration. State-3 respiratory rates of muscle mitochondria with glutamate, pyruvate, palmitoylcarnitine, and succinate as respiratory substrates were markedly reduced, whereas ascorbate/N,N,N',N'-tetramethyl-p-phenylenediamine were oxidized normally. The activities of complexes I, II, III and IV of the electron transport chain were normal, but the activities of complexes I+III and II+III, both systems requiring coenzyme Q10 as an electron carrier, were dramatically decreased. These results suggested a defect in the mitochondrial coenzyme Q10 content. This was confirmed by the direct assessment of coenzyme Q10 level by high-performance liquid chromatography in patient's muscle homogenate and isolated mitochondria, revealing levels of 16% and 6% of the control values, respectively. We did not find any impairment of the respiratory chain either in a lymphoblastoid cell line or in skin cultured fibroblasts from the patient, suggesting that the coenzyme Q10 depletion was tissue-specific. This is a new case of a muscle deficiency of mitochondrial coenzyme Q in a patient suffering from an encephalomyopathy.

Topics: Cerebellar Ataxia; Child, Preschool; Coenzymes; Electron Transport; Epilepsy; Humans; Kinetics; Lactic Acid; Male; Mitochondria, Muscle; Mitochondrial Encephalomyopathies; Muscle, Skeletal; Polarography; Retinal Diseases; Ubiquinone