Study of β-thalassemia mutations using the polymerase chain reaction-amplification refractory mutation system and direct DNA sequencing techniques in a group of Egyptian thalassemia patients

The aim of this study was the molecular characterization of ss-thalassemia (thal) mutations in a group of 95 Egyptian thalassemic patients from Fayoum in Upper Egypt, Cairo, Alexandria and Tanta in Lower Egypt and the Nile Delta. To identify these anomalies, the polymerase chain reaction amplification refractory mutation system (PCR-ARMS) technique was used, complemented by direct DNA sequencing for uncharacterized cases. In 80 of the 95 patients, the ss-thal mutation was detected by PCR-ARMS. Theniost common allele encountered in our study was M-I-6 (T -> C) (36.3%); the second most comnion mutation was IVS-I-1 10 (G -> A) (25.8 In. addition, we report three homozygous cases foi- the promoter region -87 (C -> G) allele with afrequenc ' y of 3.2 %. DNA sequencing of uncharactetized cases (14 cases, 15 alleles) revealed six cases (six alleles) ofcodon 27 (G -> T), and three cases (three alleles) of the M-II-848 (C -> A) mutation. Codon 3 7 (G -> A) in the homozygous state was found in one patient with positive consanguinity. Theframeshift codon 5 (-CT) mutation was detected in two Of our uncharactei-ized cases. The codon 15 (TGG -> TGA) mutations was detected. in onepatient (one allete, 0.5 %). All, studied cases werejully characterized, by this strategy. Screening for, ss-thalassenfic mutations using ARMS-PCRfor the seven mostfirequent alleles in Egypt succeeded in determining the ss-globin genotype in 84.2 % of our patients (91.6 % of the expected alleles). To improve the efficiency of routine screening, the PCR-ARMS mutation panel should be updated to include the repwied rare alleles. Direct DNA sequencing is an additional way to allow afull characterization of ss-thal patients in the Egptian population.