Over 95.0% of the α-thalassemia (α-thal) cases in southern China are caused by large deletions involving the α-globin gene. Here, we describe the molecular characterization of a novel 28.5 kb deletion that eliminated one of the duplicated α-globin genes in a Chinese family. The deletion breakpoint fragment involved Alu repeat sequences, suggesting a homologous recombination event. Phenotypic analysis on the heterozygous carrier of this deletion revealed that it leads to a very mild phenotype. Because of a 25.0% risk of Hb H (β4) disease in the offspring when in combination with another α(0)-thal allele, we should not ignore screening the deletion in prenatal diagnosis in order to decrease reproductive risk.
Keywords: Alu element; deletion; homologous recombination; α-globin gene; α-thalassemia (α-thal).