Electrophoretic Variation of Human Serum α<sub>1</sub>-antitrypsin in Japan

Abstract

Individual variation of serum α1-antitrypsin, a protease inhibiting protein, was studied by starch gel electrophoresis. A total of 1, 475 serum and plasma samples taken from three racial groups, namely Japanese, Ainu and U. S. A. White, were examined. Seven phenotypes altogether found were classified according to FAGERHOL's nomenclature of Pi-system. In each population group the type MM was by far the most common, while other variants had low incidence. A similar frequency distribution was found in the Japanese population to that in U. S. A. White, except that type MF was commoner and type MS rarer in the former than in the latter. A reduced heterogeneity in the Ainu population was indicated. Gene frequencies were estimated on the basis of the postulated genetic mode of codominant alleles at a locus. It is found that the α1-antitrypsin deficient type occurs also in Japan, although there is still uncertainty as to whether this is genetically a homogeneous phenotype. No difference in the trypsin inhibiting capacity was found among the three racial groups.