The Thalassemias are a diverse group of hemoglobin disorders characterized by reduced synthesis of the globin chains of Hemoglobin. Today, more than 200 mutations, affecting different levels of beta-globin gene expression, by a variety of mechanisms, are known to result in a beta-thalassemia phenotype. Beta-thalasseemia is an important health problem and its treatment costs account for considerable percentage of the national health insurance expenditure, beside the unsatisfactory treatment. Thus the need to establish an effective preventive program is paramount; delineation of the beta-thalassemia mutation in specific community is a prerequisite for implementation of preventive program in that community.
Aim of the study: Characterization of beta-thalassemia mutations in Iraqi thalassemic patients. Patients and methods: The study was conducted during the period: from December 2006 to December 2007. Sixty five thalassemic patients were included; they were transfusion dependent and they were diagnosed and registered in thalassemia centers of Baghdad, Ninawa and Al-Muthanna governorates. 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 20 beta-thalassemic mutations. Results: Out of the one hundred and thirty alleles studied, 123 (94.62%) alleles were characterized while 7 (5.38%) alleles were undetermined. Eleven alleles causing beta-thalassemia in Iraqi patients were identified in these patients, and these alleles with their frequencies were: IVS 2.1 (G>A) 21.53%, IVS 1.110 (G>A) 19.23%, IVS 1.6 (T>C) 10.76%, cod 44 (-C) 9.23%, cod 5 (-CT) 8.46%, cod 39 (C>T) 7.69%, cod 8 (-AA) 6.15%, IVS 2.745 (C>G) 5.38%, IVS 1.5 (G>C) 3.84%, IVS 1-25 (25 bpDEL) 1.53% and cod 8/9 (+G) 0.76% . Forty two patients (64.61%) carry homozygous alleles and 22 patients (33.84%) carry heterozygous alleles (compound heterozygous). Fifty patients (76.92%) have consanguineous relation between their parents, while for the homozygous patients, thirty nine patients (92.85%) showed consanguineous relation between their parents, Families with more than one affected sibling constitute 38.7%, while those with only one affected sibling constitute 61.29%. Patients with blood group A form the largest group (35.38%) and the majority of the patients are of Rh +ve (95.38%). Conclusions The eleven mutations which have been characterized in the studied group determined that the main β-thalassemia mutations in Iraq are of Mediterranean origin; with some mutations were of Kurdish and Asian Indian origins and most of beta-thalassemia mutations are of severe types (βo). 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 Iraq.