Globin synthesis in the Jamaican Negro with beta-thalassemia

ABSTRACT

Globin synthesis was studied in three Jamaican Negro families with 18 heterozygotes and 5 homozygotes for beta-thalassemia. Synthesis of the beta chain of Hb A in the peripheral blood of heterozygotes was equal to that of the alpha-chain in 10 patients and was decreased in the remainder. In one patient with Hb C beta-thalassemia the beta/alpha ratio was normal. These findings were similar to those in American Negroes, but differed from those in Caucasian with beta-thalassemia trait, in each of whom the beta/alpha ratio was decreased. Globin synthesis was balanced in the bone marrows of Negro and Caucasian heterozygotes. Despite the milder clinical disease in Negro homozygotes as compared to Caucasian patients, the beta/alpha ratios were similar in both groups. The presence of alpha-thalassemia combined with beta-thalassemia in Negro heterozygotes is not a likely explanation for the high incidence of balanced globin synthesis ratios. The expression of relative beta to alpha chain synthesis in Negro heterozygotes appears to be modified by a factor which is not linked to the delta-chain locus. The nature of this factor is not known at present.(Summary)