α-thalassemia in the United Arab Emirates

A neonatal screening survey of alpha-thalassemia (alpha-thal) among the United Arab Emirates (UAE) nationals was conducted on 418 consecutive cord blood samples. Our findings demonstrate that 49% of the cases studied were found with an alpha-globin gene defect. The gene frequency of the -alpha(3.7) was 0.2847 and that of the -alpha(4.2) was 0.0072. Four nondeletional alpha-thal mutations were found; alpha(PA-1), alpha(PA-2), Hb CS and alpha(-5nt del) with gene frequencies of 0.0036, 0.0012, 0.0024, and 0.0072, respectively. We also report here the genotype-phenotype correlation in 22 patients with Hb H disease or Hb H-like syndrome. Of these, 6 were homozygous for the alpha(PA-1) mutation, 2 were homozygous for Hb CS, and 14 were compound heterozygous for either alpha(PA-1), Hb CS, alpha(-5nt del) or -MED-I, with the -alpha(3.7). The data reported here demonstrate that a considerable heterogeneity of alpha-thal mutations occurs in the UAE and that the incidence of alpha-thal in the indigenous population is one of the highest in the world. Our clinical data suggest that Hb H disease in the UAE has, in general, a mild to moderate phenotypic presentation.