Nondeletional α-thalassemia: First description of α(Hph)α and α(Nco)α mutations in a Spanish population

Abstract

Several different deletions underlie the molecular basis of α-thalassemia. The most common α-thalassemia determinant in Spain is the rightward deletion (-α3.7). To our knowledge, however, no cases of α-thalassemia due to nondeletional mutations have so far been described in this particular Mediterranean area, Here, we report the existence of nondeletional forms of α-thalassemia in ten Spanish families. The α2-globin gene was characterized in ten unrelated patients and their relatives only when the presence of deletional α-thalassemia was ruled out. The α2-globin gene analysis was performed using the polymerase chain reaction (PCR) followed by restriction enzyme analysis or by allele-specific priming. This allowed the identification of a 5-base pair (bp) deletion at the donor site of IVS I (α(Hph)α) in 9 cases and the α2 initiation codon mutation (α(Ncoα) in one case. Although these α2-globin gene mutations are found in other Mediterranean areas, our results demonstrate their presence in the Spanish population and suggest that the α(Hph)α/αα genotype is probably the most common nondeletional form of α-thalassemia in Spain.