Hozygous Cases for Hemoglobin J Mexico (α50 (E3)Gln→Glu) Evidence for a Duplicated α Gene with Unequal Expression

Abstract

Hb J Mexico was found in 5 generations of a large Algerian family. Nine subjects have 55% Hb J although their parents, siblings and offspring may have 31%, the usual quantity found in heterozygotes. Those with 55% Hb J are considered homozygous for a chromosome carrying both a normal .alpha. chain locus and a locus for .alpha.J. The proportion of the abnormal Hb in all the subjects is in favor of an unequal expression of both loci, the amount of protein synthesis directed by the .alpha.J gene being greater than that directed by the .alpha.A. In 2 heterozygotes a slightly higher proportion of the Hb J (38%) suggests the presence of a single normal .alpha. chain locus in transition. An associated .alpha.-thalassemia was excluded by biosynthetic studies in this family.