Haplotype Analysis in Carriers of β-globin Gene Mutation Facilitates Genetic Counseling in β-thalassemia: A Cross-Sectional Study in Kerman Province, Iran

Abstract

β-thalassemia is characterized by reduced synthesis of the hemoglobin beta chain that results in microcytic hypochromic anemia and reduced amounts of hemoglobin A (HbA) on hemoglobin analysis. β-thalassemias are caused by mutations in the β-globin gene, inherited in an autosomal recessive manner. Determining molecular defects in couples carrying β-thalassemia is a prerequisite for prenatal diagnosis of the disease. In this regards, database of β-globin gene haplotypes facilitates mutation detection of the gene and helps genetic counselors to reach the goals of β-thalassemia prevention program. In this cross-sectional study, 255 couples attended genetic counseling between December 2017 and January 2019 in Afzalipour Hospital, Kerman University of Medical Scinces, Kerman, Iran as suspicious of β-thalassemia carriers. Furthermore, they were investigated using amplification refractory mutations system-polymerase chain reaction and restriction fragment length polymorphism methods for mutation screening and haplotype analysis of polymorphic sites in β-globin gene cluster, respectively. We identified 20 different types of β-globin gene mutation in 449 β-thalassemia carriers. Analysis of the pattern of Hind III/Gγ, Hinf I/5'β, Hinc II/3'Ψβ, Rsa I/5'β, AvaII/β and Hind III/Aγ polymorphic sites in 257 alleles of informative families revealed 17 different haplotypes. Haplotype 1 (77.24%) showed strong linkage with the most common mutation IVSI-5 while haplotype 5 (66.67%) was associated with the second frequent mutation IVSII-1. To our knowledge, these β-globin haplotypes are reported for the first time which are different with those found in other parts of Iran. The current haplotypes pattern data makes the counseling of β-thalassemia carriers more straightforward and the process of mutation screening faster and more accurate.