Analysis of β‐Thalassemia Mutations in Northern Thailand Using an Automated Fluorescence DNA Sequencing Technique

Abstract

A total of 218 β‐thalassemia (thal) genes from 109 β‐thal major patients were characterized using an automated fluorescence DNA sequencing technique. Eight different mutations were identified in all 218 alleles (100%). Four common mutations accounted for 96.8% [49.5% were codons 41/42 (–TTCT), 34.4% were codon 17 (A→T), 6.9% were IVS‐I‐1 (G→T) and, 6.0% were codons 71/72 (+A)]. There were three cases of −28 (A→G) and one of IVS‐II‐654 (C→T), mutations that have been previously described in Thai subjects. We also identified two mutations in the β‐globin promoter region which have not been reported in Thailand before [−31 (A→G) and −87 (C→A)]. Although these mutations are described as β+‐thal, the compound heterozygote with one of the common β0‐thal mutations exhibits the phenotype of β‐thal major. The frequency of β‐thal genes in northern Thailand were similar to the northeastern region, but different from those reported in southern and central Thailand, where IVS‐I‐5 (G→C) and IVS‐II‐654 (C→T) were the second most common anomalies, respectively. The spectrum of β‐globin gene mutations from this study will be useful for planning a prenatal diagnosis program especially for this region of Thailand.