HBS BETA(DEL)-THALASSEMIA ASSOCIATED WITH HIGH-LEVELS OF HEMOGLOBINS A(2) AND F IN A TURKISH FAMILY/

beta-thalassemia and sickle cell disease (SCD) are common disorders in Turkey. Compound heterozygosity for these two disorders (beta(S)/beta -thalassemia) is encountered frequently. In this report we present hem atological and molecular data of two Turkish siblings with beta(S)/bet a(del)-thalassemia caused by a 290 base pair (bp) deletion and associa ted with increased levels of hemoglobin A(2) (HbA(2)) and hemoglobin F (HbF). Clinical analysis of the two patients showed a mild course of the disease. Haplotypic factors involved in increasing the levels of H bF were analyzed. The two patients showed no changes from the normal s equences at the Xmnl site of G gamma-globin promoter and the (AT)(x)T- y microsatellite 5' to the beta-globin mRNA cap site, The removal of t he region between positions -125 to +78 relative to the beta-globin ge ne mRNA cap site by the 290 bp deletion is thought to allow the beta-l ocus control region to interact with the promoters of the delta- and g amma-globin genes, leading to increased HbA(2) and HbF levels. (C) 199 8 Wiley-Liss, Inc.