A novel 7·9 kb deletion causing α⁺-thalassaemia in two independent families of Indian origin

Summary. We describe the characterization of a novel 7·9 kb deletion that eliminated one of the duplicated α-globin genes, causing an α⁺-thalassaemia phenotype in two independent carriers of Suriname–Indian origin. The molecular characterization of the deletion breakpoint fragment revealed neither involvement of Alu repeat sequences nor the presence of homologous regions prone to recombination, suggesting a non-homologous recombination event. This α⁺-thalassaemia deletion was found to give rise to an atypical haemoglobin H (HbH) disease characterized by a non-transfusion-dependent moderate microcytic hypochromic anaemia in combination with a poly adenylation signal mutation of the α-globin gene (α₂ AATAAA → AATA-- --).