Globin chain synthesis in Hb J Baltimore-beta (+)-thalassemia.

An American black family in whom hemoglobin J Baltimore and beta (+)-thalassemia genes coexisted is described. The proposita is a 23-year-old woman with a hemoglobin (Hb) level of 11.5 g/dl, microcytic, hypochromic indices, increased values of Hbs A2 and F, and alpha/non-alpha synthetic ratio of 1.52. Hbs A and J Baltimore (beta 16 Gly---Asp) constituted 12% and 81.3%, respectively, of her total hemoglobin. Her sister had a very similar peripheral blood picture, but Hbs A and J Baltimore constituted 6.8% and 85.5%, respectively, of her total hemoglobin, and the alpha/non-alpha synthetic ratio was 1.39. The mother had beta(+)-thalassemia trait only, a moderate degree of anemia, and greater synthetic imbalance (alpha/non-alpha raio of 1.73). These findings suggest that the presence of the Hb J Baltimore gene ameliorates the effects of a coexistent beta-thalassemia gene.