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Genetic Modifiers of HbF in HbAA and HbAS Women From São Tomé e Príncipe: An Association Study of Common Genetic Variants in BCL11A, MYB, HBG2, and BGLT3

Front Biosci (Schol Ed). 2025 Jun 25;17(2):38388. doi: 10.31083/FBS38388.

ABSTRACT

BACKGROUND: While an increase in fetal hemoglobin (HbF) has no consequences in healthy adults, clinical benefits can be promoted in sickle cell disease (SCD) and β-thalassemia patients. Single-nucleotide polymorphisms (SNPs) in three genomic regions: the HBB gene cluster, the BCL11A gene, and the HBS1L-MYB (HMIP) intergenic region, have been associated with HbF regulation. Therefore, the present study aimed to examine the potential association of SNPs in BCL11A (rs11886868 and rs1427407), HMIP (rs66650371 and rs4895441), HBG2 (rs7482144), and BGLT3 (rs7924684) with HbF levels in an adult population sample from São Tomé e Príncipe (Central Africa).

METHODS: A total of 145 women aged 18 to 49 years were involved in this study, comprising 98 women with the normal hemoglobin (Hb) genotype (HbAA) and 47 with sickle cell trait (HbAS). From the HbAA individuals, we selected a control group of 60 subjects with normal HbF levels, ranging from 0.2% to 1.4% (mean: 0.75%), and a case group of 38 subjects with elevated HbF levels, ranging from 1.8% to 3.7% (mean: 2.35%). In the group of HbAS individuals, the HbF levels ranged from 0.4% to 3.7% (mean: 1.56%). SNP genotyping was conducted using standard molecular methods.

RESULTS: Logistic regression, in the additive model, revealed significant associations with increased levels of HbF for the minor alleles of the two BCL11A SNPs, rs11886868 [C] and rs1427407 [T], in HbAA women (p = 0.00018 and p = 0.00076, respectively). When comparisons of HbF levels were conducted among genotypes in the HbAA women, significant differences were observed for BCL11A SNPs rs11886868 and rs1427407, as well as for the HBG2 rs7482144 and BGLT3 rs7924684 variants. We found no association between HbF levels and the two HMIP variants rs66650371 and rs4895441 in the HbAA women. Among the HbAS women, no statistically significant associations were observed between the six analyzed polymorphisms and HbF levels (p > 0.05).

CONCLUSIONS: We successfully replicated the association between the two well-known BCL11A SNPs, rs11886868 and rs1427407, with HbF levels in women with the normal HbAA genotype from São Tomé e Príncipe. Other signals of association with HbF levels were identified for the SNPs HBG2 (rs7482144) and BGLT3 (rs7924684).

PMID:40613211 | DOI:10.31083/FBS38388

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