Detection of Two Rare β-Thalassemia Alleles Found in the Tunisian Population: Codon 47 (+A) and Codons 106/107 (+G)

Abstract

We here present the first report of the detection of two rare β⁰-thalassemia (thal) mutations in the Tunisian population: codon 47 (+A) and codons 106/107 (+G). To the best of our knowledge this is the second report of the codon 47 (+A) mutation, the first being identified in a Surinamese subject. The codons 106/107 (+G) mutation was first described in American Blacks, subsequently in Egyptians and Palestinians, and now in Tunisians. These mutations were detected by denaturing gradient gel electrophoresis (DGGE) screening followed by automated nucleotide sequencing. The former was found in two related β-thal major patients in the homozygous state, while the latter was identified in a homozygous state in a transfusion-dependent β-thal subject and in a sickle cell β-thal patient. Both mutations are in linkage disequilibrium with haplotype V and sequence framework 2. Given the known wide spectrum of β-thal alleles in the Tunisian population, the present report further confirms such heterogeneity. The knowledge of an updated spectrum of β-thal alleles in Tunisia must allow the implementation of a more efficient screening strategy for genetic counseling and prenatal diagnosis.

Keywords:

• β-Thalassemia (thal)
• Rare alleles
• Denaturing gradient gel electrophoresis (DGGE)