title: Rare hemoglobin variants in Tunisian population.
abstract: During the last 30 years, many studies concerning hemoglobinopathies were realized among Tunisians. More than twenty different thalassemic alleles were detected on the β-globin gene, and less are affecting the α-globin genes. Unusual hemoglobin (Hb) variants other than Hb S, Hb C, and Hb O-arab, which are the most frequent variants in Tunisia, were also detected. Eight Tunisian subjects were studied at phenotypic and molecular levels. Hematological indices and hemoglobin (Hb) pattern were performed by alkaline electrophoresis and isoelectric focusing (IEF),and the Hb fractions were quantitated by cation exchange HPLC. On genomic level, coding regions were amplified by polymerase chain reaction (PCR) followed by a sequencing of the purified PCR products using the dye terminator method. Seven uncommon Hb variants were detected and described for the first time among Tunisians. HbA2-Tunis [δ46(CD5), Gly → Glu, GGG → GAG] is the newly described δ-chain variant in our laboratory, and some other variants (Hb Constant Spring, G San Jose, and Hb J-Bangkok) are very uncommon in the Mediterranean region. We present here an updated review of the Hb variants detected among Tunisians. Twenty-one rare Hb variants were detected affecting the α1-, α2-, δ-, γ-, and β-globin genes, leading in some cases to a severe phenotype especially when the stability is completely altered. The ethnical history of Tunisia could explain this important variability of the observed rare Hb variants.
authors.affiliation: Laboratoire d'Hématologie Moléculaire et Cellulaire, Institut Pasteur, Tunis, Tunisia.
authors.forename: A
authors.initials: A
authors.lastname: Zorai
authors.forename: I
authors.initials: I
authors.lastname: Moumni
authors.forename: I
authors.initials: I
authors.lastname: Mosbahi
authors.forename: K
authors.initials: K
authors.lastname: Douzi
authors.forename: D
authors.initials: D
authors.lastname: Chaouachi
authors.forename: F
authors.initials: F
authors.lastname: Guemira
authors.forename: S
authors.initials: S
authors.lastname: Abbes
mesh_terms: D000483:Alleles; D019943:Amino Acid Substitution; D004252:DNA Mutational Analysis; D004909:Erythrocyte Indices; D014644:Genetic Variation; D005838:Genotype; D006453:Hemoglobinopathies / Q000175:diagnosis / Q000453:epidemiology* / Q000235:genetics*; D006454:Hemoglobins / Q000235:genetics*; D006801:Humans; D010641:Phenotype; D011159:Population Surveillance; D020871:RNA Stability; D014416:Tunisia / Q000453:epidemiology; D055542:alpha-Globins / Q000235:genetics; D055544:beta-Globins / Q000235:genetics; D055546:delta-Globins / Q000235:genetics
chemical_list: D006454:Hemoglobins; D055542:alpha-Globins; D055544:beta-Globins; D055546:delta-Globins
keywords: DNA sequencing; Hemoglobin variants; Tunisians