The Silent Carrier of Beta Thalassemia

Abstract

A family of Albanian descent had an unusual form of beta thalassemia. The father of two children with mild thalassemia major had normal red-cell morphology and normal levels of hemoglobins A₂ and F, whereas the mother had elevated hemoglobin A₂. The children had hemoglobin F levels of less than 12 per cent, an uncommon finding in thalassemia major. Blood samples were incubated with L-leucine-¹⁴C to determine the relative production of alpha and beta chains in reticulocytes. The decrease in beta-chain synthesis in the two siblings was less than that usually found in thalassemia major. The father and four of his relatives had a degree of impairment of beta-chain production characteristic of heterozygous beta thalassemia, despite the lack of the usual criteria for this disorder. The interaction of this "silent" form of beta thalassemia with high hemoglobin A₂ thalassemia results in thalassemia major of reduced severity.