CRISPR in the Clinic: Curative Genome Editing for Inherited Blood Diseases

CRISPR/Cas9 has transformed genome engineering by offering a precise, programmable, and efficientmethod for targeted DNA modification. First identified as a bacterial immune system, the platform uses asingle-guide RNA to direct Cas9 endonuclease to a chosen locus, where a double-strand break triggersendogenous repair pathways that disrupt, replace, or correct genes. Clinically, the most advancedapplication is exa-cel for sickle-cell disease (SCD) and transfusion-dependent βthalassemia; editedautologous hematopoietic stem cells reactivate fetal haemoglobin and have delivered transfusionindependence and crisis-free survival in Phase III trials. In December 2023 the therapy became the firstCRISPR-based product approved by the US FDA, marking a watershed for genomic medicine. Parallelefforts using Cas12a nucleases, base editors, and prime editors seek to enhance fidelity and broaden thetherapeutic spectrum to cancer, muscular dystrophy, transthyretin amyloidosis, and beyond. Continuedinnovation in delivery, high-fidelity variants, and plasmid-free ribonucleoprotein systems is expandingCRISPR’s reach while mitigating off-target effects and immunogenicity. Ethical, regulatory, and economicchallenges remain, but the technology is poised to underpin a new era of precision medicine for monogenicand complex diseases alike.