The Frequency of the ^Aγ^T Gene in the Presence and Absence of the β^s or β^C Gene in the Black Poplilation of the Southeastern USA

Abstract

Quantitative information about the three types of γ chains (^Aγ^{T, A}γ^{I, C}γ) has been obtained for the Hb F from 285 normal Black babies, 172 babies with a Hb S or Hb C heterogeneity, and from 150 babies and older patients with the SS, SC, or CC conditions by means of a high pressure liquid chromatographic micro-procedure. The frequency of the ^Aγ^T gene in the AA babies was 0.1035, while that in the SS patients was a low 0.0362. This low ^Aγ frequency in the SS POulation adequately explains the lower percentage (13.2%) of Aγ^T heterozygotes among AS newborn babies as compared to 17.9% among AA Babies. The genotype with the A_yT mutant in trans to the β^S mutation is presumed to occur about three times more frequently than that in which the A_yT mutant is in cis to the β^S mutation. A study of family members of one SS patient who has an A_yT homozygosity provided data supporting linkage of the A_yT and β^S anomalies in some Hb S heterozygotes.