A POINT MUTATION, C TO T, IN EXON-8 OF THE PORPHOBILINOGEN DEAMINASE GENE IN A JAPANESE FAMILY WITH ACUTE INTERMITTENT PORPHYRIA

Acute intermittent porphyria (AIP) is an autosomal dominant disease ch aracterized by a deficiency of porphobilinogen deaminase (PBGD). To da te, only two mutations have been reported in Japanese patients. We rep ort here another mutation of the gene in a Japanese patient, Analysis of the PCR amplified DNA fragments of the gene by direct-sequencing me thod revealed the gene abnormality responsible for the disease, The mu tation found was a point mutation, C to T, in exon 8 of the gene at po sition 346 of the housekeeping cDNA from the translation codon ATG. Th is mutation resulted in an Arg(116) to Trp substitution. Four carriers in the family were successfully diagnosed by detecting the mutation u sing restriction analysis of PCR products.