The γ-Globulin, Gm ^ab, in Nigerians

Abstract

THE γ-globulin (Gm) genetic polymorphism, first described by Grubb¹, exhibits considerable geographical variation. Steinberg, Boyer and Stauffer² recently observed a striking excess of the phenotype Gm (a + b +) among Negroes in the United States. Accordingly it was suggested that an allele, Gm ^ab, exists in coloured populations. The allele frequency of Gm ^ab among 593 Negroes from Maryland and Ohio is 0.690. The difference between this value and unity was taken as an estimate of European genetic admixture in American Negroes. Essential to this estimate was the assumption that Gm ^ab frequency is nearly 1.00 in native West Africans. Moullec³ had previously reported that 449 residents of Dakar were all Gm(a+); however, typing of Gm b was not then possible and has not since been described in a West African population.