NONDELETIONAL ALPHA-THALASSEMIA - FIRST DESCRIPTION OF ALPHA(HPH)ALPHA AND ALPHA(NCO)ALPHA MUTATIONS IN A SPANISH POPULATION

Several different deletions underlie the molecular basis of alpha-thal assemia. The most common alpha-thalassemia determinant in Spain is the rightward deletion (-alpha(3.7)). To our knowledge, however, no cases of alpha-thalassemia due to nondeletional mutations have so far been described in this particular Mediterranean area, Here, we report the e xistence of nondeletional forms of alpha-thalassemia in ten Spanish fa milies. The alpha(2)-globin gene was characterized in ten unrelated pa tients and their relatives only when the presence of deletional alpha- thalassemia was ruled out. The alpha(2)-globin gene analysis was perfo rmed using the polymerase chain reaction (PCR) followed by restriction enzyme analysis or by allele-specific priming, This allowed the ident ification of a 5-base pair (bp) deletion at the donor site of IVS I (a lpha Hph alpha) in 9 cases and the alpha(2) initiation codon mutation (alpha Nco alpha) in one case, Although these alpha(2)-globin gene mut ations are found in other Mediterranean areas, our results demonstrate their presence in the Spanish population and suggest that the alpha H ph alpha/alpha alpha genotype is probably the most common nondeletiona l form of alpha-thalassemia in Spain. (C) 1996 Wiley-Liss, Inc.