HBB and thalassemia: Although this region was historically considered to have low mutational susceptibility, the widespread implementation of next-generation sequencing (NGS) in thalassemia carrier screening has revealed an expanding spectrum of pathogenic variants within this regulatory domain, such as HBB: c.-40C>G, HBB: c.-10A>T, HBB: c.-8C>G, and HBB: c.-29G>T (11, 12).