Variations in globin chain synthesis in hereditary persistence of fetal haemoglobin

Globin synthesis was studied in four Negro families including 10 members with Hb A-HPFH and four with Hb S-HPFH. The á/O specific activity ratios in 10 of these patients with Hb A-HPFH heterozygotes were similar to those of the control group. In two patients with Hb A-HPFH, the á/O ratio was slightly decreased in one (0.84) and clearly decreased in another (0.78). In two of the patients with Hb S-HPFH the ratios were clearly decreased (0.71 and 0.75). The extended range of á/O ratios in these 14 patients is similar to that of Negro patients with á-thalassaemia trait. These studies indicate that a decreased á/O ratio may be found in HPFH, as well as in á-thalassaemia. Bone marrow globin synthesis was measured in two patients with Hb S-HPFH and decreased peripheral blood á/O ratios, and in one with Hb A-HPFH and a normal peripheral blood á/O ratio. In each patient the (á+y)/O ratio of radioactivities as well as the á/O specific activity ratio was close to I and therefore balanced, indicating more rapid decay of á-chain synthesis relative to O-chain during red cell maturation or extremely rapid destruction of newly synthesized excess O-chains in the bone marrow.(Summary)

Globin synthesis in the Jamaican Negro with beta-thalassemia

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)