pyrophosphate and Lesch-Nyhan-Syndrome

Topics: Child, Preschool; Diphosphates; Enzyme Activation; Fibroblasts; Freezing; Guanine; Humans; Hypoxanthines; Lesch-Nyhan Syndrome; Male; Metabolism, Inborn Errors; Middle Aged; Mutation; Pentosyltransferases

Topics: Adenine; Adolescent; Allopurinol; Carbon Isotopes; Carboxy-Lyases; Child; Child, Preschool; Diphosphates; Erythrocyte Aging; Erythrocytes; Hot Temperature; Humans; Infant; Lesch-Nyhan Syndrome; Orotic Acid; Pentosyltransferases

A family is reported in which each of two sisters has a son with no detectable hypoxanthine phosphoribosyltransferase (HPRT) (EC 2. 4. 2. 8) in his erythrocytes, a finding considered pathognomonic of Lesch-Nyhan disease. However, neither has the stigmata of the disease. One boy is neurologically normal, and the other is moderately retarded. There was only a slight increase in urinary uric acid, but the amounts of hypoxanthine and xanthine, and their ratios, were similar to those found in Lesch-Nyhan disease, strongly indicating that excesses of these last two oxypurines are not responsible for the symptomatology in that disease. In contrast to the nondetectable HPRT activity in the red blood cells, leukocyte lysates from the two boys have 10-15% of normal activity, possibly reflecting continuing synthesis of an unstable enzyme. This hypothesis is supported by the demonstration that at 4 degrees C HPRT activity was rapidly lost in the propositus while the activity increased in control subjects. The mother's cells were intermediate between the two. The intact and disrupted leukocytes of the hemizygote, in the absence of added phosphoribosyl converted as much hypoxanthine to inosinate as the normal cell, and appropriate tests indicated that under these circumstances enzyme concentration is not rate limiting whereas the concentration of the cosubstrate, phosphoribosyl pyrophosphate, is. The capacity for normal function in the intact mutant cell is more representative of in vivo conditions than the lysate, which may explain the important modification of clinical symptomatology, the relatively mild hyperuricosuria, and the presence of mosaicism in the circulating blood cells of the heterozygotes. A similar explanation may apply to other genetic diseases in which incomplete but severe enzyme deficiencies are found in clinically normal individuals. An associated deficiency in glucose-6-phosphate dehydrogenase in this family permitted confirmation of previous observations on linkage with hypoxanthine phosphoribosyltransferase.

Topics: Adolescent; Carbon Isotopes; Diphosphates; Epilepsy, Tonic-Clonic; Erythrocytes; Genotype; Glucosephosphate Dehydrogenase Deficiency; Heterozygote; Humans; Hypoxanthines; Inosine Nucleotides; Intellectual Disability; Lesch-Nyhan Syndrome; Leukocytes; Male; Metabolism, Inborn Errors; Mosaicism; Pedigree; Pentosyltransferases; Temperature; Uric Acid; Xanthines

Topics: Adenine; Azaserine; Carbon Isotopes; Chromatography, Thin Layer; Diphosphates; Fibroblasts; Formates; Glycine; Humans; Lesch-Nyhan Syndrome; Nicotinic Acids; Pentosephosphates; Pentosyltransferases; Purines; Ribonucleotides; Ribose; Skin

Deficient hypoxanthine-guanine phosphoribosyl transferase (HGPRT; EC 2.4.2.8) enzymes from erythrocytes of patients with hyperuricemia and with the Lesch-Nyhan syndrome migrate 15% faster in polyacrylamide gel disc electrophoresis than the normal enzyme. A half-sister of two males with partial deficiency, who had 34% of normal HGPRT activity in her erythrocytes, yielded profiles containing two distinct zones of activity; one corresponded to the enzyme found in normal individuals and one to the variant of her half-brothers. However, in her profile her variant enzyme showed notably greater activity than that observed in her half-brothers. This increase was due to an activation of the variant by normal enzyme. Electrophoresis of mixtures of normal enzyme with partially deficient enzymes from patients with hyperuricemia and with the Lesch-Nyhan syndrome also led to activation of deficient HGPRT variants by normal enzymes. Deficient variants were also activated by normal enzyme on filtration through Sephadex G-25. Experiments in which deficient variant enzymes were activated with purified normal enzyme labeled with (125)I indicated that deficient enzymes incorporate components of the normal enzyme. No such activation of deficient enzymes was ever obtained when mixtures of deficient and normal enzymes were put together in a test tube.

Topics: Athetosis; Carbon Isotopes; Chromatography, Gel; Diphosphates; Electrophoresis, Disc; Enzyme Activation; Erythrocytes; Female; Genetic Code; Genetic Variation; Guanine; Heterozygote; Humans; Hypoxanthines; Intellectual Disability; Iodine Isotopes; Isoenzymes; Lesch-Nyhan Syndrome; Male; Pentosephosphates; Pentosyltransferases; Purine-Pyrimidine Metabolism, Inborn Errors; Ribose; Self Mutilation; Sex Chromosomes; Uric Acid

Topics: Aminopterin; Autoradiography; Carbon Isotopes; Cells, Cultured; Diphosphates; Drug Resistance; Drug Stability; Fibroblasts; Humans; Hypoxanthines; Inosine; Inosine Nucleotides; Lesch-Nyhan Syndrome; Pentosyltransferases; Skin; Tritium

Topics: Adenine; Athetosis; Diphosphates; Erythrocytes; Humans; Hypoxanthines; Intellectual Disability; Lesch-Nyhan Syndrome; Purine-Pyrimidine Metabolism, Inborn Errors; Self Mutilation; Transferases

Topics: Allopurinol; Athetosis; Basal Ganglia; Diphosphates; Erythrocytes; Fibroblasts; Guanine; Humans; Hypoxanthines; Infant; Intellectual Disability; Lesch-Nyhan Syndrome; Liver; Pentosephosphates; Purine-Pyrimidine Metabolism, Inborn Errors; Purines; Ribose; Self Mutilation; Transferases; Xanthines

IMP:pyrophosphate phosphoribosyltransferase (IPPase) (EC 2.4.2.8) has been purified over 7000-fold from human erythrocytes. The purified enzyme moved as a single band on disc electrophoresis. Antisera prepared in rabbits and rats against the purified enzyme precipitated and neutralized the enzyme, but had no effect on AMP-pyrophosphate phosphoribosyltransferase (EC 2.4.2.7) activity. Evidence was found for isozymes (enzyme variants) of IPPase in normal erythrocytes. Erythrocyte lysates of five patients with Lesch-Nyhan disease reacted with antisera against normal IPPase. Lysates from LN erythrocytes blocked the inactivation of normal enzyme by the antibody. LN erythrocytes had about the same concentration of enzyme protein as normal erythrocytes. The genetic defect in LN results in the production of essentially normal amounts of an immunologically identifiable but catalytically incompetent enzyme. Thus LN is apparently the result of a mutation in a structural gene and is not due to deletion of a structural gene or defect in a regulatory gene.

Topics: Adenine Nucleotides; Animals; Athetosis; Carbon Isotopes; Chemical Precipitation; Chromatography, DEAE-Cellulose; Chromatography, Gel; Cross Reactions; Diphosphates; Drug Stability; Electrophoresis, Disc; Erythrocytes; Genes; Hot Temperature; Humans; Hypoxanthines; Immune Sera; Infant; Intellectual Disability; Isoenzymes; Lesch-Nyhan Syndrome; Mutation; Neutralization Tests; Nucleotides; Pentosephosphates; Purine-Pyrimidine Metabolism, Inborn Errors; Quaternary Ammonium Compounds; Rabbits; Rats; Self Mutilation; Sulfates; Transferases