Molecular Characterization of beta-Thalassemia Mutations in Baghdad


Background: There are currently more than 200 known mutations in the beta globin gene that cause thalassemia syndrome in the world and each ethnic population has its own unique and frequency of beta globin mutations. Delineation of the beta-thalassemia mutations in specific community is a prerequisite for implementation of preventive program in that community.Aim of the study is to characterize the spectrum of beta globin gene mutations in Baghdad patients.Patients and methods: thirty one thalassemic patients were included; they were transfusion dependent and they were diagnosed and registered in thalassemia centers in Baghdad. After DNA extraction from venous blood and PCR based DNA amplification, the allele's characterization was achieved by reverse hybridization to specific oligonucleotide probe designed to detect 22 beta-thalassemic mutations.Results: Eleven alleles causing beta-thalassemia in Baghdad were identified, and these alleles with their frequencies were:IVS 2.1 (GA)29.03% , IVS 1.110 (GA)17.74% , cod 44 (-C)14.51%, IVS 2.745 (CG)11.29% , cod 5 (-CT)9.67% , IVS 1.6 (TC)4.83% , IVS 1.5 (GC)3.22% , IVS 1-25 (25 bpDEL)3.22%, cod 8 (-AA)3.22%, cod 39 (CT)1.61% and cod 8/9 (+G)1.61%. Twenty three (74.19%) patients presented as thalassemic patient during the first year of life. Twenty five (80.64%) patients have homozygous alleles.Twenty two (75.86%) families have consanguineous relation between the parents and eleven (37.93%) families have more than one affected individual, Conclusions: 1- Eleven β-globin alleles causing β-thalassemia syndrome in Baghdad were characterized; most of these mutations are of Mediterranean type and few are of Kurdish and Asian Indian types.2- Most of the patients are homozygous, and of severe (βo) Thalassemia, and showed consanguineous relation between their parents.3- The characterization of the most common beta-thalassemia mutations provides a foundation for prenatal genetic counseling that will be part of a thalassemia prevention program in Baghdad.Key words: thalassemia, beta globin genes mutations, Baghdad, oligonucleotide, reverse hybridization