Prevalence of −α and ααα alleles in sickle cell trait and β-thalassemia patients in Mexico

The aim of this study was to determine the frequency of α-globin gene mutations in three groups of Mexican unrelated individuals. The first two groups were normal and sickle cell trait individuals from the Costa Chica region, a place with a 12.8% frequency of HbS carriers, and the third group comprised of Mexican mestizo patients with β-thalassemia. We searched for −α and −α α-thalassemia deletion alleles, as well as the ααα triplication through long-gap PCR. The alleles −α and ααα were found in the heterozygote state only; 19% of the normal subjects had the −α allele, and 2% showed the ααα allele. In individuals with the sickle cell trait, 17% had the −α deletion, and the ααα triplication was observed in 3% of these individuals. We revealed that 16% of the subjects with β-thalassemia showed the −α deletion and 28% the ααα triplication. The −α deletion was not detected in any individual. The frequency of the −α allele was roughly the same in the three groups studied; this can be explained by the fact that the three groups have common genes from Africa and the Mediterranean, where a high prevalence of α-thalassemia has been observed. To our knowledge, the frequency of ααα triplication observed in the Mexican βthalassemia patients is the highest reported. As the −α and ααα alleles are very common in our selected populations, we believe that there is a need to investigate systematically the α-globin gene mutations in all hemoglobinopathies in the Mexican population. © 2006 Elsevier Inc. All rights reserved.