Beta Globin Gene Cluster Haplotypes in Beta Thalassemia in the Kurdistan Region of Iraq.

Abstract

β-thalassemia is a prevalent inherited red cell disorder in the Kurdistan region of Iraq. To determine the chromosomal background of the frequent β-thalassemia mutations in the latter region, we investigated the β-globin gene cluster haplotypes in 202 β-thalassemia chromosomes. Haplotypes analysis utilized restriction fragment length polymorphism-PCR of seven restriction sites through the β-globin gene cluster. It was observed that IVS-II-1 (G > A) was mainly associated with haplotype III (68.8%), IVS-1-110 (G > A), codon 8/9 (+G) and codon 44 (-C) with haplotype I (in 90.0%, 100%, and 62.5% respectively), IVS-1-6 (T > C) with haplotype VI (97.4%), codon 8 (-AA) with haplotype IV (75%), codon 5(-CT) and IVS1.1 (G > A) with haplotype V (55.6% and 58.3% respectively), while codon 39 (C > T) and IVS1.5 (G > C) were mainly associated with haplotype VII (85.7% and 75% respectively). These observations support the notion that while some mutations may have originated in the Kurdistan region, others were more likely brought in by gene flow from neighboring countries or the Indian subcontinent. The association of some β-thalassemia defects with more than one haplotype may be due to mutations or recombination events.