SPECTRUM OF BETA GLOBIN GENE MUTATIONS IN EGYPTIAN CHILDREN WITH ?- THALASSEMIA

Abstract

Background: The molecular defects resulting in ?-thalassemia phenotype, in the Egyptian population show a clear heterogenic mutations pattern. PCR based techniques, including direct DNA sequencing are effective on the molecular detection and characterization of these mutations. The molecular characterization of ?-thalassemia is absolutely necessary for carrier screening, for genetic counseling, and to offer prenatal diagnosis.The aim of the work: was to evaluate the different ?-globin gene mutations in one hundred Egyptian children with ?-thalassemia. Patients and Methods: One hundred of ?-thalassemic Egyptian children, covering most Egyptian Governorates. All patients were subjected to meticulous history taking, clinical examinations, complete blood count, complete blood count, hemoglobin electrophoresis, serum ferritin and direct fluorescent DNA sequencing of ?-globin gene to detect the frequency of different mutations in studied patients. Results: The most common mutations among patients were IVS I-110(G>A) 48%, IVS I-6(T>C) 40%, IVS I-1(G>A)19%,IVS I-5(G>C)10%, IVS II-848 (C>A) 9%, IVS II-745(C>G) 8%, IVS II-1(G>A) 7%, codon"Cd"39(C> T) 4%,-87(C>G) 3% and the rare mutations were: Cd37 (G>A), Cd8 (-AA), Cd29(-G), Cd5 (-CT), Cd6(-A), Cd8/9(+G), Cd 106/107(+G), Cd27(C>T), IVS II-16(G> C), Cd 28 (-C), Cap+1(A>C), -88(C>A), all of these rare mutations were present in 1%. There was considerable variation in phenotypic severity among patients resulting from interaction of different ?° and ?+mutations, 79(79%) patients were thalassemia major (TM) and 21(21%) were thassemia intermedia (TI), without genotype phenotype association. Conclusion: Direct DNA sequencing provides insights for the frequency of different mutations in ?- thalassemic patients including rare and /or unknown ones.