Bone marrow and peripheral blood globin synthesis in an American black family with beta thalassemia.

Synthesis of globin chains in bone the heterozygotes, there was a signifimarrow and peipheral blood samples cant defect in beta synthesis in the from a black family with mild beta peripheral blood of white subjects, thalassemia was compared with simiwhile in two of three black patients the lar studies in white people. Blood and P/ ratio was in the normal range. Albone marrow were incubated with 14Cthough there was no evidence of segleucine, globin chains were isolated, regation of an alpha thalassemia gene and fl/a and ‘i/a ratios were calculated. in this black family to explain the unThe results of studies of globin synusual fl/a ratios, the presence of such thesis in homozygotes of different a gene in the heterozygotes could not races were similar, despite the differbe excluded. ences in severity of clinical disease. In T HALASSEMIA occurs commonly in black populations in Africa,’ Jamaica,2 and the United States.3.4 Both beta3 4 and alpha5.#{176}thalassemia have been described in black people in this country. The heterozygous form of beta thalassemia most frequently found is associated with an elevated percentage of hemoglobin A2 (Hb A2), a normal or slightly increased amount of Hb F, microcytosis, hypochromia, and variability in red cell size and shape. The morphologic and hemoglobin abnormalities in black people with beta thalassemia trait are similar to those seen in Mediterranean and Oriental patients.7 Despite the high frequency of elevated Hb A2 thalassemia trait in black people, reflected by an incidence of 0.8% in St. Louis3 and 0.75% in Nigeria,’ only 20 cases of homozygous beta thalassemia in this group have been reported from the United States.7 ’#{176} The disease has been generally mild, with only four of the reported patients requiring regular blood transfusions. Decreased synthesis of the beta chain of normal human hemoglobin (Hb A) has been found in the peripheral blood of patients with heterozygous and homozygous beta thalassemia.” 4 Recent reports have suggested that the moderate imbalance of globin synthesis found in reticulocytes of white people with beta thalassemia trait is more severe than that found in black people.9.’#{176} Recent studies have also shown that the ratio of beta to alpha chain synthesis is closer to unity in the bone marrow cells of Italian patients with heterozygous’5 or homozygous’#{176} beta thalassemia than in their peripheral blood.