(Original Article) Assessment of Type and Proportion of Beta-Thalassemia Gene Mutation in Health Region 3 of Thailand to Support Thalassemia Diagnostic and Confirmatory Service Plan

Abstract

More than 30 beta-thalassemia (β-thal)-causing gene mutations were identified in Thai population. Different gene mutation panels are commercially available for detection of β-thal mutations. Therefore, the selection of appropriate testing methods and mutation panels has to be tailored appropriately to the mutation prevalence in the Thai population. To date, there have been no studies on types and proportions of β-thal gene mutations in Health Region 3 of Thailand. This study aimed to investigate the types and proportions of β-thal mutations in Health Region 3 using data from 101 at-risk couples who underwent β-thal gene testing by DNA sequencing between fiscal years 2021 to 2023. A total of 15 different β-thal mutations were identified. The seven most common β-thal mutations accounted for 89.00% of all cases, including Codons 41/42 (-TCTT), Codon 26 (GAG>AAG), -28 (A>G), Codon 17 (AAG>TAG), IVS1-5 (G>C), Codons 71/72 (+A), and Codon 147 (+AC). The remaining 11.00% consisted of eight clinically significant β-thal mutations, namely -31 (A>G), Codon 26 (GAG>TAG), IVS1-1 (G>T), Codon 35 (TAC>TAA), IVS2-654 (C>T), Hb Malay, Hb Dhonburi, and Hb D-Punjab. Evaluation of mutation coverage using the β-Globin mutation Southeast Asia panels containing 22 and 23 mutations demonstrated detection rates of 89.92% and 89.00%, respectively. Notably, both panels were able to detect up to 89.00% of the seven most common mutations identified in this study. For cases in which no mutation was detected by either panel, confirmatory testing by DNA sequencing was required to increase the likelihood of identification of clinically significant β-thal mutations.