Fetal hemoglobin modulates neurocognitive performance in sickle cell anemia

Purpose of the study: Fetal hemoglobin (HbF) isa modifier of the clinical and hematologic phenotype of sickle cell anemia (SCA). Three quantitative trait loci (QTL) modulate HbF expression. The neurocognitive effects of variants in these QTL have yet to be explored. We evaluated the relation between 11 SNPs in the three HbF QTL: BCL11A, MYB, the HBB gene cluster, and full-scale intelligence (IQ) in SCA. Patients and methods: The prospective longitudinal cohort study, Sickle Cell Clinical Research and Interven-tion Program, was used as a discovery cohort (n = 166). The genotypes for 11 SNPs were extracted through whole genome sequencing and were analyzed using an additive model. A polygenic score for HbF (PGS(HbF)) integrating the numbers of low HbF alleles from 11 SNPs was analyzed as a continuous variable. The Cooper-ative Study of Sickle Cell Disease (n = 156) and the Silent Cerebral Infarction Transfusion (n = 114) Trial were used as two independent replication cohorts. Benjamini and Hochberg approach was used to calculate false discovery rate adjusted p-value (pFDR). Results: HbF was positively associated with IQ (minimum raw p = 0.0018) at pFDR < 0.05. HbF mediated the relationship between two BCL11A SNPs, rs1427407 and rs7606173, HBS1L-MYB: rs9494142, and PGSHbF with IQ (minimum raw p = 0.0035) at pFDR < 0.05. Conclusion: As the major modulator of the severity of SCA, HbF also influences neurocognition, which is done through mediation of its QTL. These findings have implications for early identification of neurocognitive risk and targeted intervention.(c) 2022 Elsevier Masson SAS. All rights reserved.

Automated summary

The study aimed to evaluate the relationship between 11 SNPs in three HbF QTL and the intelligence of SCA patients. The results showed that HbF was positively associated with IQ, and HbF mediated the relationship between its QTL and IQ.