Genetic studies of familial amyloid polyneuropathy in the Arao district of Japan: I. The genealogical survey.

A genealogical survey of familial amyloid polyneuropathy in the Arao district of Japan was undertaken, and the data were analysed statistically. The survey revealed 92 patients (46 males and 46 females) in 9 families. Thirty-one of the patients (16 males and 15 females) are alive. For 44 patients, the mean age of onset was 34.1 years (range 20-46 years). The penetrance corrected for late onset was 83.5% by Morton's method. The segregation ratio of 18 sibships in which one of the parents was affected was 36 +/- 6% for single ascertainment and 46 +/- 5% for complete ascertainment; the corresponding figures of 14 sibships in which neither parent was affected was 30 +/- 7% for single ascertainment and 40 +/- 6% for complete ascertainment. The results of the analysis were consistent with the assumption of an autosomal dominant mode of inheritance.