Rapid Detection of β-Thalassemia Alleles in Egypt Using Naturally or Amplified Created Restriction Sites and Direct Sequencing: A Step in Disease Control

Abstract

β-Thalassemia (thal), the most common genetic disorder in Egypt, is a major health problem with an estimated carrier rate of 9–10%. This study, aimed at describing the β-globin gene mutations in the Suez Canal area, an important Egyptian region, to provide a foundation for a disease control program. We studied 44 β-thalassemic patients (and their relatives) from 35 families living in this region. The commonest mutations were genetically diagnosed using naturally or amplified created restriction sites. Less frequent mutations were characterized by denaturing gradient gel electrophoresis (DGGE) and direct sequencing. Twelve different mutations were identified in 51 unrelated chromosomes. The three most frequent mutations were IVS-I-110 (G→A), IVS-I-1 (G→A) and IVS-I-6 (T→C). The spectrum of rarer mutations was heterogeneous and differed from that reported in other areas of Egypt. We also identified the first homozygous case of a rare mutation, codon 24 (−G; +CAC), displaying a thalassemia major phenotype. Parental consanguinity was high (60.6%) with 35.7% of the compound heterozygous patients having consanguineous parents. These data provide insights for the distribution of β-thal alleles in this region, and could be used as a basis for genetic counseling and prenatal diagnosis.

Keywords:

• β-Thalassemia mutations
• Denaturing gradient gel electrophoresis (DGGE)
• Restriction fragment length polymorphism (RFLP)