Globin Synthesis in the Jamaican Negro with Beta‐Thalassaemia

Summary. Globin synthesis was studied in three Jamaican Negro families with 18 heterozygotes and five homozygotes for β‐thalassaemia. Synthesis of the β‐chain of Hb A in the peripheral blood of heterozygotes was equal to that of α‐chain in 10 patients and was decreased in the remainder. In one patient with Hb C β‐thalassaemia, the β/α ratio was normal. These findings were similar to those in American Negroes, but differed from those in Caucasians with β‐thalassaemia trait, in each of whom the β/α 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 β/α synthesis ratios were similar in both groups. The presence of α‐thalassaemia combined with β‐thalassaemia in Negro heterezygotes is not a likely explanation for the high incidence of balanced globin synthesis ratios. The expression of relative β‐ to α‐chain synthesis in Negro heterozygotes appears to be modified by a factor which is not linked to the δ‐chain locus. The nature of this factor is not known at present.