The genetic studies of familial amyloid polyneuropathy in the Arao district of Japan: II. Studies of genetic markers in blood

Blood samples from 21 patients with familial amyloid polyneuropathy (FAP) and 81 normal family members among 7 affected families in Arao were tested for 9 blood group systems, 8 serum polymorphic proteins, 12 red cell polymorphic enzymes, and HLA. One of the most important findings was the existence of two relatively rare variants, i.e., group specific component Gc^*1A2 and phosphoglucomutase PGM1^*7 in 3 families. This observation suggests that the three genealogically independent families may have a common ancester. Phenotype AB in the ABO blood group system, phenotype 1 in the haptoglobin system, and M₂ gene in the protease inhibitor system were not seen, and phenotype Jk(a+b-) in the Kidd groups was found in only one patient. Whether these observations reflect the characteristics of FAP in the Arao district or that of FAP itself can not be determined from the present study. No phenotype attributable to Caucasians was found, hence the study provides no support for the hypothesis that the gene for FAP was introduced into Japan by the Portuguese.