A nationwide molecular characterization of β-thalassemia and variants among a referred trio families in Malaysia

Abstract Thalassemia is a significant health burden in Malaysia. This report presents a retrospective analysis of nationwide diagnostic data compiled over seven years, investigating β-thalassemia spectrum in 731 referred family trios. Genomic analysis used gap-PCR, ARMS-PCR, MLPA, Sanger sequencing, and exome sequencing to validate rare CNVs. We identified 468 at-risk couples, with 440 children inherited biallelic mutations. Heterogeneous mutations were recorded among Peninsular Malaysian children with 43 β-, four δ-, 11 α-thalassemia and variant types, and five α-globin duplications. Among children in Sabah, 15 β-, one δ-, and two α-thalassemia and variants, and one α-globin duplications were recorded. Sarawak exhibited lowest heterogeneity. In Peninsular Malaysia, β E was most prevalent among Malays, followed by IVS 1–5 (G > C), β Malay , and IVS 1–1 (G > T). IVS 2–654 (C > T) and − 28 (A > G) were observed only among Chinese individuals in this referred cohort, while Cd 41/42 -TTCT was common to both ethnicities. β E /β-thalassemia was the most frequent disease with 188 cases. In Sabah, homozygous β Filipino was the most frequent genotype across multiple ethnicities, with 35.2% (31/88) of these cases exhibiting concomitant -α 3.7 . Overall, 15.2% (111/731) of children with HBB mutations had concomitant α-thalassemia, and 10 had α-triplications. These findings highlight the necessity of HBA genotyping for accurate genetic counseling. We present two novel mutation, codon 122 (TTC > TGC) mutation (HBB:c.368 T > G; p.Phe123Cys) named β Tanah Merah , and α-globin cluster duplication, ααα 91 (NC_000016.10:g.87820_179080dup). This comprehensive dataset is essential for improving molecular diagnostics and optimizing DNA analysis workflows in highly heterogeneous populations.