BETA-THALASSEMIA IN TURKEY

A review is presented of the various βthalassemia alleles observed in nearly 191 patients with βthalassemia major and their 182 heterozygous relatives. Determination was by gene amplification and dot-blot hybridization with synthetic probes, specific for 27 different mutations. Eighteen mutations have been observed; six of these acount for nearly 83% of all thalassemia abnormalities (Table I). A new mutation, i.e. a G {right arrow, tailed} C mutation at the acceptor splice site of IVS-I, was found in one teenager who was homozygous for this disease. the high consanguinity among the families was considered the main reason for the high number of patients with a homozygosity for the IVS-I-110 (G {right arrow, tailed} A) mutation. Combinations of different mutations were present in many patients; some were mildly affected because of the specific mutation present on one chromosome. Combinations of classical βthalassemia and an abnormal hemoglobin mainly concerned Hb S. Hbs Knossos and Lepore were rare occurrences. A comparison of hematological data for adults with heterozygosities for some of the common alleles confirmed the low Hb A2 values in IVS-I-6 (T {right arrow, tailed} C) heterozygotes and the high Hb F values for codon 8 (-AA), IVS-II-1 (G{right arrow, tailed} A), and IVS-I-1 (G{right arrow, tailed} A) heterozygotes. © 1990 Informa UK Ltd All rights reserved: reproduction in whole or part not permitted.