Study of beta-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 beta-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 beta-thal mutation was detected by PCR-ARMS. The most common allele encountered in our study was IVS-I-6 (T-->C) (36.3%); the second most common mutation was IVS-I-110 (G-->A) (25.8%). In addition, we report three homozygous cases for the promoter region -87 (C-->G) allele with a frequency of 3.2%. DNA sequencing of uncharacterized cases (14 cases, 15 alleles) revealed six cases (six alleles) of codon 27 (G-->T), and three cases (three alleles) of the IVS-II-848 (C-->A) mutation. Codon 37 (G-->A) in the homozygous state was found in one patient with positive consanguinity. The frameshift codon 5 (-CT) mutation was detected in two of our uncharacterized cases. The codon 15 (TGG-->TGA) mutations was detected in one patient (one allele, 0.5%). All studied cases were fully characterized by this strategy. Screening for beta-thalassemic mutations using ARMS-PCR for the seven most frequent alleles in Egypt succeeded in determining the beta-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 reported rare alleles. Direct DNA sequencing is an additional way to allow a full characterization of beta-thal patients in the Egyptian population.
El-Gawhary
Somaia
S
Department of Clinical Pathology, Cairo University Hospitals, Kasre El Eini Hospital, Cairo, Egypt.
El-Shafie
Shahira
S
Niazi
Manal
M
Aziz
Mona
M
El-Beshlawy
Amal
A
D000595:Amino Acid Sequence; D001483:Base Sequence; D002648:Child; D002675:Child, Preschool; D003241:Consanguinity; D004252:DNA Mutational Analysis / Q000379:methods*; D004534:Egypt; D005260:Female; D005820:Genetic Testing; D005828:Genetics, Population; D005914:Globins / Q000235:genetics*; D006801:Humans; D008297:Male; D009154:Mutation; D021141:Nucleic Acid Amplification Techniques; D017354:Point Mutation; D016133:Polymerase Chain Reaction; D017086:beta-Thalassemia / Q000235:genetics*
D005914:Globins