Molecular Basis of β‐Thalassemia in the Population of Tunisia

Abstract

The present study attempts to delineate the spectrum of β‐thalassemia (thal) mutations in Tunisia by studying a large population from different parts of the country. A total of 285 unrelated subjects, 190 of whom had β‐thal major, 72 with Hb S/β‐thal, one with Hb C/β‐thal, one with Hb O‐Arab/β‐thal and 21 β‐thal carriers, were studied. The molecular defects were detected in 97.7% of the β‐thalassemic chromosomes (n = 475). Nineteen different β‐thalassemic alleles were identified. Two mutations, namely codon 39 (C→T) and IVS‐I‐110 (G→A) accounted for 70.0% of the studied chromosomes, followed by IVS‐I‐1 (G→A) (4.5%). Five other mutations, frameshift codon (FSC) 44 (–C), codon 30 (G→C), IVS‐I‐2 (T→G), IVS‐II‐745 (C→G), and FSC 6 (–A), are not uncommon in this population, while the remaining 11 mutations, IVS‐I‐5 (G→A), − 30 (T→A), codons 25/26 (+ T), IVS‐I‐6 (T→C), FSC 5 (–CT), IVS‐II‐848 (C→A), FSC 8 (–AA), –87 (C→G), IVS‐I‐5 (G→C), IVS‐II‐1 (G→A) and IVS‐II‐849 (A→C) are quite rare; four of these have not been previously reported in the Tunisian population. Potential origin and spread of these mutations to Tunisia are also discussed.

• β‐thalassemia (thal)
• Mutations
• Regional distribution
• Tunisia