azaguanine and Gout

A family is reported where four males have developed hyperuricemia, renal damage and, except for the youngest person affected, gout at an early age. The disease appears to be inherited as an X-linked recessive metabolic error. Clinically the patients have developed classical, tophaceous gout before the age of 25 and have suffered repeated attacks of renal colic. Renal tubular damage with decreased ability to concentrate and acidify urine was seen in a family member of only 16 years of age. Progressive renal failure seems to develop slowly. None in the family has shown neurologic symptoms, and two of the four affected men are apparently of at least average intelligence, two slightly below average. One female carrier has repeatedly passed uric acid stones. Studies of the red blood cell lysate have shown a normal activity of enzyme hypoxanthine phosphoribosyltransferase, and an increased level of adenine phosphoribosyltransferase. Skin fibroblasts from affected family members grew normally in the presence of 8-azaguanine. Administration of azathioprine to the patients did not decrease their serum uric acid levels. This is the first family described with this type of disorder of the purine metabolism.

Topics: Adenine Phosphoribosyltransferase; Adolescent; Adult; Azaguanine; Azathioprine; Erythrocytes; Female; Fibroblasts; Genes, Recessive; Gout; Humans; Hypoxanthine Phosphoribosyltransferase; Kidney Diseases; Kidney Failure, Chronic; Male; Middle Aged; Purine-Pyrimidine Metabolism, Inborn Errors; Uric Acid

The toxic and mutagenic effects of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) on cultured diploid human fibroblasts were studied. When 10(5) cells per 60 mm dish were exposed to MNNG for 4 h in Ham's medium F10 containing 0.02 M HEPES buffer at pH 6.8, MNNG concentrations of less than 1 X 10(-6) M resulted in cell survivals near 100%, while the average survival was less than one percent at concentrations greater than 5 X 10(-6) M. After treatment with MNNG, cells were subjected to selection using optimal conditions for the detection of diploid human fibroblasts that are resistant to the guanine-analogs AG and TG because they contain altered or deficient HPRT. The induced mutant frequency was maximized by allowing a 5 to 7 day post-treatment interval for the expression of the mutant phenotype and by replating the cells at the beginning of selection at a population density of less than 450 cells per cm2. Careful attention was given to counting statistically adequate numbers of mutants and to accurately determining cell survival and replating cloning efficiencies. Independent dose-response experiments gave induced mutant frequencies as high as 7.0 X 10(-4) to 8.8 X 10(-4) mutants per viable cell at about 5% survival, compared to a spontaneous mutation rate of 3.7 X 10(-6) to 7.2 X 10(-6) mutants per cell generation. The AGr mutants observed after treatment with MNNG were phenotypically stable and closely resembled prototype AGr cultures derived from humans who have inherited mutant X-chromosomal alleles for HPRT.

Topics: Azaguanine; Cell Survival; Dose-Response Relationship, Drug; Drug Resistance; Fibroblasts; Gout; Humans; Lesch-Nyhan Syndrome; Male; Methylnitronitrosoguanidine; Mutagens; Mutation; Phenotype; Skin

Topics: Azaguanine; Binding Sites; Drug Resistance; Erythrocytes; Fibroblasts; Gout; Guanine; Heterozygote; Humans; Hypoxanthine Phosphoribosyltransferase; Hypoxanthines; Kinetics; Lesch-Nyhan Syndrome; Phosphoribosyl Pyrophosphate

For study of the basis of an X-linked form of gout in man, several clonal lines deficient in hypoxanthine-guanine phosphoribosyltransferase (EC 2.4.2.8) were selected from the human lymphoblast line WI-L2 by spontaneous and mutagen-induced resistance to 10 muM 8-azaguanine. Three groups could be defined: (1) clones with less than 1% of normal enzyme activity, unable to incorporate [(3)H]hypoxanthine detectable by radioautography, unable to tuilize exogenous hypoxanthine as a source of purines, and showing a 2- to 4-fold accelerated rate of production of early intermediates in de novo purine biosynthesis; (2) clones with 56-63% of normal enzyme activity, decreased incorporation per cell of [(3)H]hypoxanthine measured by radioautography, able to utilize exogenous hypoxanthine, and showing 1.2- to 2.8-fold purine overproduction; (3) clones with 10-15% of normal enzyme activity, able to utilize hypoxanthine but not incorporating amounts detectable by radioautography, and showing a 2.3- to 2.5-fold increase in purine biosynthesis. Resistant clones generated by ICR 191 mutagenesis resembled Group 1 clones. Heat inactivation studies in crude extracts from certain clones in Group 2 suggest a structural gene mutation, but no qualitative alteration in enzyme could be detected by starch gel electrophoresis. These phenotypes have persisted over at least 300 generations of nonselective growth, with retention of a diploid karyotype.

Topics: Autoradiography; Azaguanine; Cell Line; Clone Cells; Diploidy; Drug Resistance; Electrophoresis, Starch Gel; Genes; Genotype; Gout; Guanine; Humans; Hypoxanthines; Karyotyping; Mutation; Pentosyltransferases; Purine-Pyrimidine Metabolism, Inborn Errors; Purines; Spleen; Tritium

Topics: Adenine; Adolescent; Aminopterin; Azaguanine; Blood Urea Nitrogen; Carbon Isotopes; Cell Line; Creatinine; Drug Resistance; Electrophoresis, Starch Gel; Erythrocytes; Fibroblasts; Gout; Guanine; Humans; Hypoxanthines; Lesch-Nyhan Syndrome; Male; Mercaptopurine; Pentosyltransferases; Purines; Uric Acid