FAMILY STUDY OF ACUTE INTERMITTENT PORPHYRIA AND HEREDITARY COPROPORPHYRIA IN NIIGATA AND AKITA PREFECTURES, JAPAN

Simple screening tests, urinary porphobilinogen (PBG) for acute interm ittent porphyria (AIP) and fecal coproporphyrin for hereditary copropo rphyria (HCP), were performed in a family study of AIP and HCP. Urinar y PBG was positive in 93 of 211 members of 10 AIP families, but was ne gative in 568 of 572 controls. Fecal coproporphyrin was positive in 54 of 108 members of 10 HCP families, but was negative in 188 controls. A dominant inheritance was assumed by a chi-square test and Weinberg s egregation ratio. Worsening factors around puberty were suggested by t he onset age and cumulative percentage of genetically loaded cases. Se x-related expression of symptoms was also inferred by a higher inciden ce of both porphyrias in females than in males. Fitness and penetrance of both porphyrias were good. An l-triiodothyronine loading test was the most useful for the detection of masked carriers of AIP. In conclu sion, AIP and HCP in Japan show a dominant inheritance with sex-relate d metabolic and clinical manifestations.