Beta-globin gene cluster haplotypes in Iranian patients with beta-thalassemia

ABSTRACT

Beta-globin gene cluster haplotypes are useful in diagnosis of particular molecular defects in Beta-thalassemia, prenatal diagnosis of Beta-thalassemia, and elucidating population affinities. Beta-globin gene cluster haplotypes were studied in 150 Beta-thalassemia minor and 52 healthy in-dividuals from the Fars province of Iran. DNA was extracted from leukocytes of whole blood by phe-nol-chloroform. Haplotype was determined by PCR-RFLP technique. There were 26 out of 150 with homozygous haplotypes. Haplotype I was found as the most prevalent haplotype among both patients and normal individuals. Out of 26 patients bearing homozy-gous haplotypes, 12 [46.2%] had typical haplotype I and 3 [11.5%] had atypical haplotype I. The prevalence of haplotype I in normal control subjects was around 43% [45 out of 104 Beta A chromo-somes]. The second prevalent haplotype was haplotypes V [15.4%] and III [15.4%] for homozygous patients and controls, respectively. The most frequent mutation in patients was IVS II.1 [G-->A] that was not linked to a single haplotype. IVS I.110 [G-->A] mutation was linked to haplotype I. Mutation in codon 30 [G -->A] was associated with haplotype V. Being Haplotype I the most prevalent haplotype in Beta-thal and BetaA chromosomes, implies that Beta-thalassemia mutations might have arisen in the chromosomal background common in the popula-tion, rather than due to selection pressure or gene flow [migration]. Patients with haplotype IX had the highest HbF levels compared to other haplotypes