Friday, Jul 24, 2026 The claims desk. Receipts included. POWERED BY LENZ ↗
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SCIENCE

The Claim

Many CRISPR-based sickle cell disease clinical trials primarily edit the BCL11A gene or its enhancer to reactivate fetal hemoglobin rather than directly repairing the HBB mutation.

Verified by Lenz ·

The Short Version

The evidence shows that BCL11A or its erythroid enhancer has been a central target in multiple CRISPR sickle cell trials, including the approach behind Casgevy/exa-cel. These programs aim to reactivate fetal hemoglobin rather than directly fix the HBB sickle mutation. Other editing strategies exist, but they do not undermine the claim’s use of “many.”

Caveats

  • The claim does not mean all CRISPR sickle cell trials use BCL11A; some target HBG promoters, other regulatory elements, or direct HBB correction.
  • “Many” is accurate, but it is not a precise numerical share of the entire trial landscape.
  • Some cited webpages and trial aggregators are weak sources; the strongest support comes from peer-reviewed papers, ClinicalTrials.gov, and major medical journals.

The Receipts

  1. CRISPR-Cas9 Gene Editing for Sickle Cell Disease and β-Thalassemia

    The New England Journal of Medicine

  2. CRISPR/Cas9 gene editing for curing sickle cell disease

    PubMed Central

  3. Genome Editing for Sickle Cell Disease: A Little BCL11A Goes a Long Way

    PubMed Central

  4. CRISPR-Cas9 to induce fetal hemoglobin for the treatment of β-hemoglobinopathies

    PubMed Central

  5. Gene therapy for sickle cell and β-thalassemia works by disrupting three-dimensional genome structure

    St. Jude Children’s Research Hospital

  6. Safety and efficacy studies of CRISPR-Cas9 treatment of sickle cell disease through disruption of an LRF binding site in the γ-globin gene promoters

    Molecular Therapy

  7. Efficacy and Safety of Brl-101, CRISPR-Cas9-Mediated Gene Editing of the BCL11A Erythroid Enhancer for Transfusion-Dependent β-Thalassemia

    ScienceDirect

  8. Disease Roundup: Four Gene-Editing Candidates in the Clinic for Sickle Cell Disease

    CRISPR Medicine News

  9. Sickle cell gene therapy: 75 years of science

    Boston Children’s Hospital

  10. Comparative analysis of CRISPR-Cas9, lentiviral transduction, and HBB correction strategies for sickle cell disease gene therapy

    ScienceDirect (journal article)

+ 16 more sources — see the full list on Lenz

Filed Under

BCL11ACRISPRFetal HemoglobinHBBSickle Cell Disease

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