Molecular characterization of beta-thalassemia in Syria

This study concerns the determination of beta-thalassemia alleles and other hemoglobin variants in 82 patients from Syria. We have characterized 146 c hromosomes and found 17 different beta-thalassemia mutations, and one beta- globin chain variant that gives rise to the abnormal uh S. The eight most c ommon beta-thalassemia mutations were the IVS-I-110 (G-->A), IVS-I-1 (G-->A ), codon 5 (-CT), -30 (T-->A), codon 39 (C-->T), IVS-I-6 (T-->C),IVS-II-1 ( G-->A), and codon 15 (TGG-->TAG). These mutations accounted for almost 75% of the total beta-thalassemia chromosomes. We identified 34 different genot ypes with a high level of homozygosity. The various beta-thalassemia mutati ons were characterized using gene amplification with specific oligonucleoti de primers, restriction enzyme analysis, denaturing gradient gel, electroph oresis and direct sequencing. By combining these three approaches we were a ble to detect mutations in almost 90% of the chromosomes studied. Our findi ngs provide a sound foundation on which to base a preventive program for th alassemia and we believe that the data that we present will facilitate the improvement of medical services such as carrier screening, genetic counseli ng, and prenatal diagnosis. Furthermore a detailed knowledge of the molecul ar pathology of beta-thalassemia will strongly improve the prenatal diagnos is services in Syria.