IMPORTANCE OF THE GENETIC PICTURE AND GLOBIN-SYNTHESIS IN DETERMINING THE CLINICAL AND HEMATOLOGICAL FEATURES OF THALASSEMIA INTERMEDIA

Carriers of thalassemia intermedia [12] were studied. Their clinical and hematological picture was distinctly different from that in both heterozygotes and homozygotes for .beta. thalassemia. Several genetic patterns were responsible for thalassemia intermedia: .beta./.delta..beta. thalassemia, .alpha.2.beta./.beta. thalassemia, .beta./.beta. thalassemia-heterocellular HPFH [hereditary persistence of fetal Hb]. In a few subjects the genetic picture indicated that the patients were homozygous for .beta. thalassemia, in spite of the mildness of the clinical situation. The lack of genetic uniformity was reflected in very wide Hb A2 (2.5-8.7%) and Hb F (7.5-96.9%) ranges, as opposed to the noticeable degree of biochemical uniformity indicated by the very similar imbalance of globin chain synthesis: 0.33-0.54 for the non-.alpha./.alpha. chain ratio in the peripheral blood. The mean for this parameter (0.43 .+-. 0.05) was significantly different (P < 0.001) from that observed in heterozygous carriers (0.60 .+-. 0.10) and homozygous carriers (0.11 .+-. 0.05) for .beta. thalassemia. The marrow blood displayed a comparable pattern. The severity of thalassemia is probably attributable to the degree of chain synthesis imbalance.