Clinical and hematologic features of beta(o)-thalassemia (frameshift 41/42mutation) in Thai patients

Background and Objectives. Frameshift 41/42 mutation is the most common mut ation of P-thalassemia found in Thailand. We studied clinical and hematolog ic features in 84 patients and relatives with frameshift 41/42 to determine whether it is possible to predict phenotypic severity from genetic factors . Design and Methods. The clinical phenotypes and hematologic data of Thai pa tients with frameshift 41/42 were studied. a thalassemia, Hb Constant Sprin g (HbCS) genes and the presence of Xmnl-(G)gamma polymorphism were studied in patients who had mild symptoms. Results. Homozygotes for frameshift 41/42 and compound heterozygotes for fr ameshift 41/42 and beta (0)-thalassemia produced severe symptoms and have a thalassemia major phenotype. Combination of frameshift 41/42 and beta (0)- thalassemia or Hb E produced mild to moderate symptoms with thalassemia int ermedia phenotype and severe symptoms with thalassemia major phenotype. The alpha -inheritance of alpha -thalassemia or HbCS gene or the presence of X mnl-(G)gamma polymorphism was not associated with mild disease in patients with frameshift 41/42 and HbE. Interpretation and Conclusions. The clinical phenotype of homozygotes for f rameshift 41/42 and compound heterozygotes for frameshift 41/42 and beta (0 )-thalassemia could be used to predict a severe phenotype with thalassemia major. However, the clinical phenotype of compound heterozygotes of framesh ift 41/42 and beta (0)-thalassemia or Hb E were variable and could not be a ccurately predicted. Associations between concomitant alpha -thalassemia or HbCS of the presence of Xmnl-(G)gamma polymorphism and a mild clinical phe notype are not apparent, indicating the involvement of other ameliorating d eterminants or genetic modifications. (C) 2001, Ferrata Storti Foundation.