First Report of β-Thalassemia Intermedia in a Patient Compound Heterozygous for –92 (C>T) and Codons 36/37 (–T) Mutations

Molecular and geographical heterogeneity of hemoglobinopathy mutations in Azerbaijanian populations

With the carrier rate of 4%-8.6%, β-thalassemia is one of the most prevalent hereditary disorders in Azerbaijan. Taking into consideration the high frequency of β-thalassemia as well as the occurrences of several other hemoglobinopathies, we conducted a large genotyping study to investigate the mutational background of common hemoglobinopathies in the country. Α- and β-globin genes were evaluated in the carriers of mutations identified via hematological indices and hemoglobin fractions (n = 1,757). Genotyping of β-thalassemia carriers identified through population screening revealed 32 mutations, with codon 8 [-AA]-34.96%, IVS-II-1 [G > A]-16.35%, and IVS-I-110 [G > A]-10.12% leading the spectrum. Analysis of associations of β-thalassemia mutations with geographical regions of the country identified the strongest association between codon 8 [-AA] and Shaki-Zaqatala, and codon 5 [-CT] in Mountainous Shirvan regions (ri > 6.00; p < 0.05). HbS, HbD-Punjab, and HbE were the most prevalent among our variant hemoglobin cohort, commonly inherited in compounds with β-thalassemia than in the homozygous state. We identified nine α-thalassemia mutations, 20.5 kb and 3.7 kb deletions together accounting for 74% of the spectrum. Point mutations of α-thalassemia were less common among our observations and were mainly inherited in compounds with deletions. Our results allow a better understanding of the wide spectrum of mutations in Azerbaijan and highlights the high heterogeneity of hemoglobinopathies in the local population.

Hb Knossos (HBB: c.82G > T), β-globin CD 5 (-CT) (HBB: c.17_18delCT) and δ-globin CD 59 (-a) (HBD: c.179delA) mutations in a Syrian patient with β-thalassemia intermedia

Background

Beta thalassemia (β-thal) is an inherited hemoglobin disorder characterized by reduced synthesis of the hemoglobin that results in microcytic hypochromic anemia. β-Thalassemia intermedia (TI) is a clinical term of intermediate gravity between the carrier state and β-thalassemia major (β -TM).

Case presentation

We describe a 12-year-old male proband originating from Al-Quneitra province - southwest Syria. Hematological investigations revealed, pallor and anemia (Hb 9 g/dl). The mean cell volume (MCV) 64 fL; mean cell hemoglobin (MCH) 21.8 pg. Capillary electrophoresis (CE) electropherogram revealed low level of Hb A1 (36.2%), high level of Hb F (62.2%) and low level of Hb A2 (1.6%). The proband requires blood transfusion occasionally. Direct DNA sequencing and Polymerase chain reaction-restriction fragment length polymorphism (PCR/RFLP) for mutations detection were used. The molecular analysis revealed the presence of rare β⁺ Hb Knossos codon 27 (G > T) (HBB: c.82G > T) variant associated with β⁰ codon 5 [−CT] (HBB: c.17_18delCT) mutation in beta-globin (β-globin) gene and δ⁰ codon 59 [−A] (HBD: c.179delA) mutation in delta-globin (δ-globin) gene. The proband tested negative for the common deletional forms of alpha thalassemia (α-thal). Polymorphism of the Xmn-I locus (HBG2: c.-211C > T) revealed that the proband had a homozygous [TT] for Xmn-1 locus.

Conclusions

To our knowledge, this is the first report of beta thalassemia intermedia due to combination of Hb Knossos /codon 5 [−CT] associated with δ⁰ codon 59 [−A] in Syrian patient. On the other hand, in Syria, β-thal carriers who have low level of Hb A2 due to decreased δ-chain production, different δ-thal gene mutations must be screened to avoid the failure diagnosis of β-thal disease.

Codon 14 (+T) (HBB: c.44_45insT): a Rare β-Thalassemia Mutation Reported Only in Azerbaijan

Codon 14 (+T) (HBB: c.44_45insT) is a very rare β-thalassemia (β-thal) mutation previously reported in three β-thal major (β-TM) patients of Azerbaijani origin. None of the previous reports described the genotype-phenotype correlation of the mutation. We here report the first case of homozygous codon 14 together with data of the heterozygous parents.