title: delta-Aminolevulinic acid dehydrase (porphobilinogen synthase) in two families with inherited enzyme deficiency.
abstract: The inheritance of a deficient delta-aminolevulinic acid dehydrase (ALA-D; synonym: porphobilinogen synthase; EC 4.2.1.24) was studied in blood samples of two families over three generations. The propositus in each family was a young male acute hepatic porphyria patient with an almost complete ALA-D deficiency in the homozygous state (ALA-D activity less than 2% of controls). Heterozygotes are clinically non-affected (mean ALA-D 36% of controls). The mode of transmission could be traced by enzyme activity and electrophoretic polymorphism studies. Heterozygotes are detected by the demonstration of enzyme activity in the gel. The notation D was used for the gene expressing the defective enzyme. The "phenotype" D-1 was observed in six, the "phenotype" D-2 in three of all heterozygotes studied. These results are compatible with a single normal allele in heterozygotes responsible for enzyme activity. Quantitative assays and the segregation pattern in both families suggest a 3-allele-system for the inheritance of ALA-D deficiency.
mesh_terms: D000483:Alleles; D005260:Female; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D008107:Liver Diseases / Q000201:enzymology / Q000235:genetics*; D008297:Male; D010375:Pedigree; D000623:Porphobilinogen Synthase / Q000097:blood / Q000172:deficiency* / Q000235:genetics; D011164:Porphyrias / Q000201:enzymology / Q000235:genetics*
chemical_list: D000623:Porphobilinogen Synthase