Genetic determinants of β-thalassemia intermedia in Pakistan.

This study covers the molecular characterization of clinically diagnosed beta-thalassemia intermedia (beta-TI) patients in Pakistan. Blood samples of beta-TI patients were collected from all four provinces of Pakistan throughout the period of 2011-2013. The study was carried out using allele-specific primers through polymerase chain reaction or sequencing to determine both alpha- and beta-thalassemia (alpha- and beta-thal) mutations, and restriction enzymes for the characterization of beta-globin gene arrangements. In a total of 63 patients, the IVS-I-5 (G>C) was the most frequent mutation (33.88%). The codon 30 (G>A) and IVS-II-1 (T>C) mutations were found only in the Punjabi ethnic group, while the codon 30 (G>C) and Hb S (HBB: c.20A>T) mutations were found only in the Pashtoon and Sindhi ethnic groups, respectively. In case of alpha-globin genotypes, 44 patients were normal (alpha alpha/alpha alpha), six patients carried the alpha alpha/-alpha(3.7) genotype, 12 patients carried the -alpha(3.7)/-alpha(3.7) genotype, while one patient had the alpha alpha/alpha alpha alpha(anti) (3.7) genotype. We found that haplotype I was the most frequent, mostly associated with the codons 8/9 (+G) mutation, while the Saudi haplotype was found only with Hb S.