βthalassemia in Bulgaria

Analyses of DNA from 64 patients with thalassemia major using the hybridization technique of amplified DNA with radiolabeled synthetic oligonucleotide probes identified 13 different βthalassemia mutations (Table I). the codon 39 (C {right arrow, tailed} T) and IVS-I-110 (G {right arrow, tailed} A) mutations occurred most frequently but seven additional mutations were observed which were present at frequencies of 3.9 to 10.2% This broad spectrum of βthalassemia alleles complicates the analyses for institutions involved in prenatal diagnosis. Promoter mutations were rare and the frequencies of two other mild mutations [IVS-I-6 (T {right arrow, tailed} C) and the poly A mutation] were relatively low indicating that βthalassemia is a severe disease among Bulgarians. the high frequencies of 4.7-5.5% for the four frameshifts at codons 5, 6, 8, and 8/9 may be specific for this population.