Association of polymorphisms in the HBG1‐HBD intergenic region with HbF levels

BACKGROUND: Increased levels of fetal hemoglobin (HbF) can improve the clinical course of the patients with sickle cell anemia (SCA) or beta-thalassemia. The HBG1-HBD intergenic region plays an important role in this process. However, very few studies investigated whether the variations in this region have an effect on HbF expression. METHODS: We retrieved all the SNP data in the HBG1-HBD intergenic region and defined the haplotype blocks, then performed cluster analysis and selected a tagSNP. A total of 500 normal individuals and 300 beta-thalassemia carriers were enrolled. After routine blood and hemoglobin capillary electrophoresis testing, beta-thalassemia mutations were detected using PCR-reverse dot blot. The genotypes of the rs4910736 (A > C) and rs10128556 (C > T) were determined using Sanger sequencing; the relationship between the two SNPs and the levels of HbF was analyzed. RESULTS: Two haplotype blocks were constructed. Block 1 included seven haplotypes divided into two groups M and N by 11 tagSNPs, among which rs4910736 was selected as a tagSNP, while block 2 included three haplotypes. We found that the haplotypes of block 1 were statistically associated with HbF levels, but the non-tagSNP rs10128556 was shown to be more strongly associated with HbF levels than rs4910736. CONCLUSION: This work proved that the haplotypes in the HBG1-HBD intergenic region and SNP rs10128556 are both statistically associated with HbF levels, revealing the association of polymorphisms in the HBG1-HBD intergenic region with HbF levels.