5558131 GENETICS OF IRANIAN ALPHA THALASSEMIA PATIENTS; COMPREHENSIVE ORIGINAL STUDY

Abstract

Background: Alpha thalassemia is the most prevalent monogenic gene disorder in the world and especially in Mediterranean countries. In the current hematological phenotype of patients with different genotypes, and also the effect of missense mutations on the protein function and stability were evaluated in a large cohort study. Methods: One thousand five hundred and and sixty subjects were participated in the study and divided into two groups; 259 normal subjects and 1301 alpha thalassemia carriers. Genomic DNA was extracted and analyzed using ARMS PCR, Multiplex Gap and direct sequencing. The effects of single nucleotide change on the protein function and stability were predicted by free available databases of human polymorphisms. Results: Sixty-three different genotypes were seen in the patients. The more prevalent was heterozygote form of -α3.7 (41.4%) followed by -α3.7 homozygote(11.6%) and - -MED(3.8%). The significant differences were seen in mean hemoglobin level [F=20.5, p<0.001] between the Alpha globin genotypes, when adjusted for gender. Moreover, 28 different mutations were found in our study. A significant relationship was seen between ethnicity and the alpha globin mutation frequency X2 (df;8) = 38.36, p <0.0001). Conclusion: Different genotypes could be displayed as different phenotypes. The mutation frequency distributions in our region is different from other parts of Iran. Significant differences are seen in the spectrum of mutation frequency between various ethnicity. Finally, some missense mutations maybe did not considerably effect on the proteins and could be a neutral mutations. Keywords: Alpha Thalassemia, Genotype, Phenotype, Southwest of Iran