Document Type : Original Article(s)
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Abstract
Background: Approximately 180 mutations have been described in β-thalassemia worldwide with specific spectrum in each ethnic population. This study determines the spectrum and the frequency of β-thalassemia mutations in patients with β-thalassemia trait and sickle cell-β-thalassemia. Methods: Fifteen compound heterozygous sickle cell thalassemia (SCT) and 23 β-thalassemia trait patients were studied using reverse dot blot, denaturing gradient gel electrophoresis and direct genomic sequencing. Results: We detected distinct β-thalassemia alleles in 15 compound heterozygous of SCT and 23 β-thalassemia trait patients. The most common mutation was IVSII-1(G®A), found in 15 of the 38 thalassemia chromosomes. IVSII.1 (G→A) mutation is a single nucleotide change of G to A at intervening sequence 2 position 1 of β-globin gene, detected in 11 out of 23 chromosomes in A/β-thalassemic patients and in four out of 15 chromosomes of SCT patients. This mutation constituted about 39% of the mutations in both groups. The -25bp 3َ IVSI, deletion of 25 base pairs from 3' end of intervening sequence 1 of β-globin gene, was found to be the second prevalent mutation among all chromosomes. Conclusion: Defining thalassemia mutations are necessary to establish prenatal diagnosis programs leading to lower medical cost. Amongst 10 different types of mutation detected in β-thalassemic patients from South of Iran, two mutations of IVSII-1(G®A) and -25bp 3َ IVSI were the most predominant β-thalassemic alleles.
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