δ0-Thalassemia in cis of βKnossos globin gene: first homozygous description in thalassemia intermedia Libyans and first combination with codon 39 (C→T) in thalassemia intermedia Tunisian patients

Chaima Abdelhafidh Sahli; Amina Bibi; Faida Ouali; Hajer Siala; Sondess Hadj Fredj; Rym Othmani; Fekria Ouenniche; Mondher Cheour; Zohra Fitouri; Saida Ben Becher; Taieb Messaoud

doi:10.1515/cclm-2012-0102

Article

δ⁰-Thalassemia in cis of β^Knossos globin gene: first homozygous description in thalassemia intermedia Libyans and first combination with codon 39 (C→T) in thalassemia intermedia Tunisian patients

Chaima Abdelhafidh Sahli , Amina Bibi , Faida Ouali , Hajer Siala , Sondess Hadj Fredj , Rym Othmani , Fekria Ouenniche , Mondher Cheour , Zohra Fitouri , Saida Ben Becher and Taieb Messaoud

Published/Copyright: April 20, 2012

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From the journal Clinical Chemistry and Laboratory Medicine Volume 50 Issue 10

Abstract

Background: β-Thalassemia is the most common disease among hemoglobinopathies in North African and Arab populations. In the present study we report the first description of the β-Knossos codon27 (G→T) (β^Knossos) allele in cis with the δ⁰59 (-A) mutation in thalassemia intermedia patients in Tunisia and Libya.

Methods: This identification was carried out by sequencing analysis of the whole coding regions of the δ- and β-globin genes.

Results: We noted that heterozygous inheritance of the β^Knossos mutation results in a mild β-thalassemia phenotype with a low level of HbA₂ while homozygous leads to intermediate β-thalassemia with an atypical high performance liquid chromatogram showing a complete absence of HbA₂ and HbF. Compound heterozygosity of the β^Knossos with β⁰codon39 (C→T) is identified in a Tunisian proband for the first time and gives rise to a mild phenotype. In both families, the δ⁰codon59 (-A) and the β^Knossos alleles were found to be associated with a single Mediterranean β-haplotype I similar to that observed in previous reports from Algeria, Egypt, Cyprus, and Turkey.

Conclusions: The chromosome supporting the β^Knossos and the δ⁰codon59 (-A) alleles seems to be of a single Mediterranean origin. Premarital screening studies in families in which only one of the parents has typical aspects of β-thalassemia trait and the other has a normal HbA₂ level associated with abnormal red cell indices becomes a necessity to avoid missing thalassemia carriers.

Keywords: β-thalassemia; δ-thalassemia; hemoglobin Knossos; North Africa; thalassemia intermedia

Corresponding author: Amina Bibi, MD, Biochemistry Laboratory, Children’s Hospital, Bab Saadoun Square, Tunis, Tunisia Phone: +216 98 414607, Fax: +216 71 566463

Received: 2012-1-12

Accepted: 2012-3-19

Published Online: 2012-04-20

Published in Print: 2012-10-01

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https://doi.org/10.1515/cclm-2012-0102

Keywords for this article

β-thalassemia; δ-thalassemia; hemoglobin Knossos; North Africa; thalassemia intermedia