XmnI polymorphism in homozygous/compound heterozygous BT group is 13%. The most common genotype associated with XmnI polymorphism was IVSI-5/IVSI-5.

Background/aim: Fanconi anemia (FA) is an autosomal recessive disease determined by mutations in at least 16 genes, with distinct distributions in different populations. To the best of our knowledge, there are no reports regarding the molecular basis of the disease in FA patients in Pakistan. The current study aimed to determine the frequency of FANCC gene mutations, i.e. IVS4+4A>T, del322G, and R548X, in FA patients.Materials and methods: Genomic DNA was obtained from 36 FA patients. All samples were analyzed by polymerase chain reaction and restriction fragment length polymorphism techniques.Results: Mutation IVS4+4A>T was identified in 26 (72.2%) patients. It was homozygous in 6 and heterozygous in 20 patients. Del322G and R548X were found with the following prevalences: del322G, 5.6%, and R548X, 5.6%. Patients with these two mutations were compound heterozygotes having concomitant IVS4+4A>T mutation. Conclusion:These results suggest that mutation IVS4+4A>T is the most prevalent mutation in our group of patients. This analysis of Pakistani patients also suggests that there is no significant difference between IVS4+4A>T homozygotes and the rest of the patients with regard to severity of clinical phenotype.

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The aim of this study was to analyze the rare β-thalassemia (β-thal) mutations in the Pakistani population. A total of 8716 unrelated Pakistani individuals having children with transfusion-dependent thalassemia were investigated by amplification refractory mutation system-polymerase chain reaction (ARMS-PCR) for the previously reported common and rare β-thal mutations. Genomic sequencing of the β-globin gene and its immediate 5' and 3' flanking regions was done where no known mutation was found. Out of the 8716 individuals studied, 88 (1.0%) were not characterized by ARMS-PCR. Genomic sequencing revealed that 67 (0.82%) individuals had 19 different β-thal mutations including one novel mutation (HBB: c.136delT). The remaining 21 (0.26%) individuals did not show any mutation on the β-globin gene and its immediate flanking regions. The characterized alleles included seven (0.09%) in the 5' untranslated region (5'UTR), 29 (0.35%) in the coding regions, and 31 (0.38%) in the splice junction regions. HBB: c.92+1G>A and HBB: c.113G>A were the most frequently seen rare mutations. The spectrum of β-thal mutations in the Pakistani population is very diverse. In addition to the already reported mutations, another 19 different types of mutations were found. Interestingly, 21 individuals who had children with transfusion-dependent thalassemia and one known β-thal mutation, did not show any mutation on the β-globin gene. HBB: c.92+1G>A and HBB: c.113G>A are the most frequently seen rare mutations in Pakistan.

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