12/ Huge thanks to our collaborators & participants! Our study advances understanding of HbF regulation & genetic modifiers in SCD. Stay tuned for more insights! There’s still work to do, but these findings push us closer to tailored treatments that improve patient outcomes.

11/ Genetic diversity impacts SCD GWAS results

-New HbF variants confirmed, but small effects
-CRISPRi highlights functional variants
-Rare DNMT1 variant might influence HbF—but more validation is needed

10/ Functional testing in HUDEP-2 cells did not confirm DNMT1 p.Gly95Ser as causative (yet). More work is needed to assess its potential role in high HbF levels & clinical protection in SCD.

9/A DNMT1 missense variant (p.Gly95Ser) stood out found in an SCD patient with 28.9% HbF (stable over time, no hydroxyurea). This rare variant resembles hereditary persistence of fetal hemoglobin (HPFH) mutations.

8/Finally, we analyzed rare coding variants in 1,354 SCD patients via whole-exome sequencing (WES). No genome-wide significant genes emerged, likely due to sample size limitations.

7/ We found effects at BACH2 & KLF1—both transcription factors involved in HbF regulation.

Two gRNAs at BACH2 (rs4707609) increased HbF
Two SNPs near KLF1 (rs2242514, rs10404876) increased HbF

6/ CRISPR & Single-Cell Analysis
We performed CRISPR inhibition (CRISPRi) & scRNA-seq on 14 HbF SNPs in HUDEP-2 erythroid cells. Our goal? To connect genetic variants with functional effects. We found effects at BACH2 & KLF1—both transcription factors involved in HbF regulation.

5/ Why didn’t ABCC1 replicate?
SCD patients experience high oxidative stress. Their cells may have maxed out the HbF-inducing pathway, thus drugs targeting ABCC1 might not work as expected. This could explain why some NRF2-activating drugs failed in SCD trials.

4/ A case study: ABCC1 & Oxidative Stress
GWAS in non-SCD individuals identified ABCC1 (MRP1) as an HbF regulator. Lab studies showed that reducing MRP1 activity increases oxidative stress & HbF. Sounds promising, right? But we couldn’t replicate this in SCD patients (P > 0.2).

3/ Our study: 3,740 SCD patients. We tested whether these new HbF-associated variants hold up in well-characterized SCD cohorts. We confirmed 5 new HbF-associated variants at: ASB3, BACH2, PFAS, ZBTB7A, KLF1.

2/ What’s new? Recent Genome-Wide Association Studies (GWAS) have identified new genetic variants influencing HbF levels—BUT these findings mostly come from non-SCD cohorts. Can these associations be replicated in SCD patients? That’s what we set out to test. Cato. et al. (2023).

1/ Why does HbF matter?
Higher HbF levels = less severe SCD complications
It reduces sickling, lowers complications, and improves survival. This is why finding genetic regulators of HbF is so important for developing better therapies.
Orah S. Platt, et. al,. N Engl J Med 1994