Dr Ah Kahn Syed 🐭 (@arkmedic)

“CRISPR deleted the extra chromosome behind Down syndrome. In a world-first, scientists have used CRISPR to delete the extra chromosome that causes Down syndrome – offering hope for future treatments of genetic conditions once thought untouchable. Down syndrome (trisomy 21) is caused by the presence of a third copy of chromosome 21, leading to developmental, cognitive, and health challenges. It’s one of the most common genetic conditions, affecting 1 in 700 births. Yet, no curative treatment exists. That may be changing. In a new proof-of-concept study, researchers used CRISPR-Cas9 gene editing to eliminate the extra chromosome from lab-grown cells derived from individuals with Down syndrome. These included both pluripotent stem cells and skin fibroblasts, representing a broad cellular model. The result? A dramatic restoration of normal gene expression and function. The team even fine-tuned the edit by temporarily suppressing the cell’s DNA repair mechanisms, which made the chromosome removal more precise and efficient. Right now, this method is confined to cell cultures. It’s not yet safe or ready for human trials, especially because removing a full chromosome carries risks of unintended damage. But if refined, it could one day be used on neurons and glial cells – offering an unprecedented way to intervene in early development or possibly even in utero. It’s not just a breakthrough for trisomy 21. This method could potentially apply to other deadly trisomies, like 13 and 18, which often result in miscarriage or early death. Read the study: "Trisomic rescue via allele-specific multiple chromosome cleavage using CRISPR-Cas9 in trisomy 21 cells." PNAS Nexus, 2025.” https://pubmed.ncbi.nlm.nih.gov/39967679/#:~:text=Abstract,chromosome%20loss;%20human%20trisomy%2021.