Molecular Basis of α-Thalassemia in Algeria

Abstract

An epidemiological molecular study was carried out to evaluate the spectrum and allelic frequency of alpha-thalassemia (alpha-thal) defects in Algeria. A series of 153 randomly selected blood donors was screened for 10 alpha-thal alleles described in the Mediterranean area. In addition, six unrelated cases with hematological and biochemical data suggestive of Hb H disease were investigated. Our data revealed an allele frequency of 4.6%. The presence of alpha(0)-thal determinants (-alpha(20.5) and --MED I) was observed both in Hb H patients and in the randomly collected samples. Overall, the -alpha(3.7) deletion was the most prevalent allele (2.9%), followed by the alpha(Nco I)alpha (HBA2:c.1A>G) allele (0.6%) and by the alpha(Hph I)alpha (HBA2:c.95 + 2_95 + 6delTGAGG), -alpha(20.5), --(MED I) alleles (0.3% each). The -alpha(4.2) deletion was observed in only one Hb H patient. These results outline the heterogeneity of the alpha-thal alleles in Algeria which reflects the anthropological history of the country. Because of their frequency, alpha-thal alleles are probably frequent modulators of prevalent beta-globin gene-related hemoglobinopathies in Algeria.

Alpha-Thalassemia in North Morocco: Prevalence and Molecular Spectrum

“…Genetic analysis identified six different α -thalassemia defects, diagnosed for the first time in the Moroccan population. In Tunisia, nine mutations were described to be responsible for this disease [37], and six in the Algerian population [38]. The regional prevalence being estimated at 0.96% seems to be the lowest in the Mediterranean basin (Algeria 4.6%, Tunisia 4.8-5.4%, Libya 1-5%, Cyprus 10.6%) [39, 40].…”

“…- α 3.7 deletion is the most common mutation found in the North Moroccan population (allele frequency 0.33%). However, it is less frequent compared with the other Mediterranean countries (Algeria 2.9% [38], Tunisia 4.5%, Sicily 4.1% in 2002 [37], and Cyprus 7.7% in 2000 [39]). - α 3.7 deletion was associated, in one newborn, with a heterogeneous deletion in cis on the ζ gene already detected in his father.…”

Simultaneous Detection of Hb Constant Spring (α142, TAA>CAA, α2) and The α2 IVS-I Donor Site (−TGAGG) Deletion by a Simple Polymerase Chain Reaction-Based Method in Iran

“…In those at-risk regions, methods allowing rapid, cost effective and accurate diagnosis of molecular defects of α-globin genes are welcome. Although a PCR-RFLP method using the HphI restriction enzyme is commonly performed for detection of the α2 IVS-I donor site deletion (8)(9)(10), this is the first time that a PCRbased method, which allows simultaneous characterization of two common α-globin point mutations, is described. This rapid, accurate and low cost method can be useful for rapid characterization of the α2 IVS-I donor site and Readthrough mutations such as Hb CS (α2) for genotype-phenotype analysis and appropriate genetic counseling.…”

The incidence of alpha-thalassemia in Setif, Algeria

“…In a recent study, in addition to these mutations, α Nco I α was shown and α-thal allele frequency found 4.6%, with the -α 3.7 haplotype being 2.9% in randomly selected blood donors in Algiers, the capital city of Algeria which is located at the Mediterranean Sea coast [5].…”