Clinical, hematological, and molecular features in sicilians with Hb S‐β‐thalassemia

The clinical, hematological, and molecular features of 81 patients with Hb S‐β‐thalassemia and relatives from 76 unrelated families are reported. We analyzed the β‐thalassemia mutations and the β S haplotypes in all patients and detected 6 different β‐thalassemia alleles: codon 39 (C→T) (39 cases), IVS‐I‐1 (G→A) (12 cases), IVS‐II‐1 (G→A) (4 cases), IVS‐l‐6 (T→C) (6 cases), IVS‐I‐110 (G→A) (14 cases), and IVS‐II‐745 (G→C) (6 cases). Eighty patients had haplotype #19 or the Benin type and one had haplotype #17 or the Cameroon type. The type of β‐thalassemia allele had the greatest influence on the phenotypic expression; this was observed for patients with Hb S‐β‐thalassemia and for simple β‐thalassemia heterozygotes. The mild IVS‐I‐6 (T→C) mutation produced borderline abnormal erythrocytic indices and Hb A 2 levels in heterozygotes. Overall, there was a milder expression in β S β + patients (only 7.7% presented severe disease) than in those with the β S β° condition (22.6% had the severe form of the disease). © 1992 Wiley‐Liss, Inc.