A novel HBD gene mutation associated with normal-range hb A2 in β-thalassemia carriers

β-thalassemia is one of the most common single-gene inherited conditions in the world, prevalence of β-thalassaemia in south China is 3–4%,increased Hb A2 level is one of the most important markers of β-thalassemia heterozygous carriers.Interaction of HBD gene defect with β-thalassemia can result in the normal Hb A2 β-thalassemia, potentially leading to a misdiagnosis of β- thalassemia carrier state. This study aimed to identify a novel mutation in HBD gene resulted in normal Hb A2 levels in β-thalassemia carriers, and explore the underlying mechanism of the novel HBD gene mutation using a minigene splicing assay and in vivo validation. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00277-026-06892-7.