Distribution of the Serum Group-Specific Components in Israel

Abstract

THE group-specific components (Gc) of human sera, described in 1959 by Hirschfeld¹, constitute a system of α₂-globulins varying in relative electrophoretic mobilities. Family studies disclosed that this system is controlled by two co-dominant autosomal alleles, Gc¹ and Gc² (refs. 2 and 3). Three common phenotypes can be distinguished by immunoelectrophoresis as indicated by the different position and shape of the Gc-precipitates: a fast-moving component (Gc 1–1), and a slow-moving component (Gc 2–2) correspond to the homozygous types; the heterozygous type is characterized by the presence of both components forming an extended, two-peaked precipitate (Gc 2–1). Population surveys have revealed considerable variations in the distribution of Gc allele frequencies in different geographical areas and ethnic groups. The frequencies of Gc² varied from 0.306 in Indians (Bombay) to 0.023 in a population of Navajo Indians^4,5. In the various Jewish populations in Israel the distribution of several genetic traits has been extensively investigated. Differences in the distribution of blood groups⁶, and incidence of erythrocyte glucose-6-phosphate dehydrogenase deficiency⁷, have been demonstrated. The differences demonstrated in the distribution of haptoglobins were not statistically significant. Significant differences in the taste sensitivity to phenylthiourea were found only in males. The present investigation is concerned with the distribution of the group specific components among various populations in Israel.