Molecular Heterogeneity of β-Thalassemia in Algeria: How to Face Up to a Major Health Problem

This study concerns the molecular characterization of β-thalassemia (β-thal) alleles in 210 chromosomes. In the studied population, mutations were detected in 98% of the β-thalassemic chromosomes. Twenty-one molecular defects have been found, where the five dominant mutations, IVS-I-110 (G>A), nonsense mutation at codon 39 (C>T), the frameshift codon (FSC) 6 (−A), IVS-I-1 (G>A), and IVS-I-6 (T>C), account for 80% of the independent chromosomes. Among the remaining alleles, 16 different mutations were identified, half of them being described for the first time in Algeria. These include the −101 (C>T) and the −90 (C>T) mutations in the distal and proximal promoter elements, respectively, the FSC 8 (−AA), IVS-I-5 (G>T), IVS-I-128 (T>G), FSC 47 (+A), IVS-II-1 (G>A), and the substitution in the polyadenylation signal (poly A) site AATAAA>AATGAA. Haplotype analyses on rare variants were performed. The possible origin of these mutations either by founder effect or by migrations is discussed, and raises the quest...