Molecular Characterization of α-Thalassemia in Pakistan.

Common α-thalassemia (thal) rearrangements were studied in a normal random population and in six ethnic groups of Pakistan. Analyses of 204 individuals from the normal population revealed the presence of only the --α[SUP3.7] allele with an overall frequency of 8.3%. Ethnic differences were statistically significant for Pashtoon vs. Balochi (p < 0.0005) and Pashtoon vs. Sindhi (p < 0.002). Two hundred and eighty-five thalassemia patients were also studied to identify rare α-thal alleles. In this group, 24.6% of the patients had one or two α genes deleted. Two rare alleles in the Pakistani population, -α[SUP4.2] (0.2%) and ααα[SUPanti3.7] (0.9%), were identified in these patients. The -α[SUP4.2] allele was found only in Sindhis, while ααα[SUPanti3.7] was present in Punjabis, Sindhis and Balochis. Five patients with triplicated α genes were homozygous for either the β[SUP+] or the β[SUP0] genotype. [ABSTRACT FROM AUTHOR]