In a pioneering scientific milestone, Japanese researchers have successfully removed the extra chromosome responsible for Down syndrome using CRISPR gene-editing technology, restoring normal cell function in the process.
Led by Dr. Ryotaro Hashizume at Mie University, the team is the first to eliminate the root cause of Down syndrome at the cellular level. Their technique selectively deletes the third copy of chromosome 21—while preserving the normal two—marking a significant advancement in genetic research.
Down syndrome affects approximately 1 in every 700 births worldwide and is caused by trisomy 21, where a person’s cells contain an extra chromosome 21. This genetic anomaly interferes with normal development, resulting in intellectual disabilities, distinct facial features, and increased susceptibility to conditions such as heart disease and early-onset Alzheimer’s.
The research team used a precise method known as allele-specific editing, which instructs CRISPR-Cas9 to target and cut DNA sequences found only in the surplus chromosome. After being cut, the unstable chromosome is naturally lost as cells divide.
In lab tests, the approach removed the extra chromosome in 30.6% of cells. Treated cells showed normalized gene activity, protein production, and survival rates—closely mirroring healthy cells. Notably, the technique worked in both stem cells and adult skin cells derived from people with Down syndrome.
While clinical application remains years away, the findings represent a major leap toward potential treatments that could one day lessen or prevent the more serious health impacts associated with Down syndrome.