A NOVEL MISSENSE MUTATION IN EXON-4 OF THE HUMAN COPROPORPHYRINOGEN OXIDASE GENE IN 2 PATIENTS WITH HEREDITARY COPROPORPHYRIA

Hereditary coproporphyria (HCP) is an autosomal dominant disease chara cterized by a deficiency of co-proporphyrinogen oxidase. To date, four mutations of the gene have been reported. We report here another muta tion in two Japanese families with HCP, which was revealed by analysis of polymerase chain reaction (PCR)-amplified DNA fragments of the gen e by a direct-sequencing method. A point mutation, G to A, was found i n exon 4 of the gene at position 538 of the cDNA from the reported put ative translation initiation codon ATG. This mutation results in a gly cine to arginine substitution at amino acid 180. Two carriers in the f amily were successfully diagnosed by detecting the mutation using rest riction analysis of the PCR products.