Different types of beta-thalassemia intermedia. A genetic study in 20 patients.

20 patients with beta-thalassemia intermedia classified according to the results of genetic studies are presented. (1) 9 patients with beta-thalassemia intermedia homozygous for beta-thalassemia with increased Hb-A2 are reported. (2) 8 patients with beta-thalassemia intermedia, 3 homozygous for beta-thalassemia with normal levels of Hbs.A2 and F, 5 heterozygous for both this and beta-thalassemia with increased Hb-A2 are presented. (3) 2 families with beta-thalassemia intermedia heterozygous for both beta-thalassemia with increased HbA2 and 'silent" beta-thalassemia are reported. Two different varieties are presented.