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J Lab Physicians. 2018 Oct-Dec;10(4):370-373. doi: 10.4103/JLP.JLP_22_18.

HBG2 -158 (C>T) polymorphism and its contribution to fetal hemoglobin variability in Iraqi Kurds with beta-thalassemia minor.

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Scientific Research Center, College of Science, University of Duhok, Duhok, Iraq.
Department of Pathology, College of Pharmacy, University of Duhok, Duhok, Iraq.
Department of Pathology and Scientific Research Center, College of Medicine, University of Duhok, Duhok, Iraq.



Hemoglobin (Hb) F% is increased in up to half of beta-thalassemia (β-thal) carriers. Several polymorphisms have been linked to such variability in different populations, including HBG2 - 158(C>T) (Xmn I polymorphism) on chromosome 11. To determine the role of this polymorphism in such variability among Iraqi Kurds, the current study was initiated.


A total of 102 consecutive patients diagnosed as β-thal minor were enrolled. The enrollees had their diagnosis based on peripheral blood counts and high-performance liquid chromatography to determine HbA2 and HbF. All enrollees had their DNA extracted by phenol-chloroform method and Xmn I polymorphism detected by restriction fragment length polymorphism-polymerase chain reaction.


The mean age (standard deviation [SD]) of the 102 enrollees was 25.4 (14.0) years, and the enrollees included 48 males and 54 females. Xmn I polymorphism was identified in heterozygous state in 46 (45.1%) patients and in homozygous state in one patient (0.98%). Thus, the minor allele frequency of this polymorphism was 0.235 in the studied group. There were no significant differences in red cell indices and HbA2% in carriers of the minor allele compared to noncarriers, while HbF% and absolute HbF concentrations were significantly higher in the former subgroup (P = 0.032 and 0.014, respectively). This polymorphism's contribution to HbF variability was found to be 5.8% in the studied sample. Furthermore, those with HbF ≥2% were 3.2 folds more likely to carry the minor allele.


Xmn I polymorphism is frequently encountered in Iraqi Kurds with β-thal minor, and it is significantly associated with higher fetal hemoglobin in these patients.


Beta-thalassemia; Iraq; Kurds; Xmn I polymorphism; rs7482144

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