BACKGROUND:Thalassemia is known as the commonest monogenic disorder with an imbalanced rate of globin chains production of adult hemoglobin.Despite the available information about the thalassemia etiology,its phenotype varies from each patient to another.This study aimed to evaluate the hematological parameters of patients with the same-α3.7 homozygote and heterozygote genotypes to amend screening programs.METHODS:In this observational study,we evaluated 1301 thalassemia suspected patients who referred to the Thalassemia and Hemoglobinopathy Research Center of Ahvaz University of Medical Sciences,Khuzestan,Iran during 2014-2016.According to the genotyping studies,patients divided into 2 groups with-α3.7/αα (n =646) and-α3.7/-α3.7 (n =181)genotypes.Thereafter,distribution of hematological parameters evaluated in both groups.RESULTS:The mean age in heterozygous and homozygous groups was 25.7±4.5 and 26±4.4 years old,respectively.The degree of anemia was considerably varied in patients with the same genotype.MCV,RBC and MCH showed a wide distribution in patients.CONCLUSION:The findings presented here suggest that other molecular mechanisms along with α-globin gene mutations could be involved in determining the phenotypes of alpha thalassemia patients.