The daily lives of people with Down syndrome are marked by immense challenges: developmental delays, cognitive disorders or increased risks of early diseases such as Alzheimer’s. Until now, medicine was content to provide support, failing to act on the genetic root of the syndrome. But today, the cursor has moved. In the laboratories of Beth Israel Deaconess Medical Center in Boston, Massachusetts in the United States, a team of neurologists has just proven that it is possible to silence the genetic error that causes the disease.
The challenge was significant. Unlike other genetic diseases where only one gene is defective, Down syndrome involves an entire extra chromosome. To tackle this colossus, scientists had the genius idea of copying nature. In women, one of the two X chromosomes is naturally deactivated by a gene called XIST. The researchers therefore used the famous CRISPR molecular scissors to insert this XIST gene directly into the third chromosome 21 of diseased cells. Result? The extra chromosome goes to sleep and therefore stops sending disruptive signals to the body.
This technical success, detailed by Gizmodo, marks a break with previous attempts. Where older methods failed to reach enough cells, this new approach boasts an impressive success rate, hitting between 20% and 40% of targeted cell lines. It’s a giant leap that finally makes the idea of humane treatment credible. Dr. Volney Sheen, lead author of the study, does not hide his enthusiasm: “This approach allows us to overcome a major obstacle”he says, emphasizing that this protocol is now adaptable on a large scale.
The technical performance is remarkable, especially since the process is safe: the tool has been calibrated to target only one copy of the chromosome, thus avoiding affecting the two other copies necessary for the proper functioning of the body. By managing to silence this genetic stowaway without creating chaos in the rest of the body, researchers prove that chromosome therapy is no longer science fiction, but a laboratory reality just waiting to emerge.
A glimmer of hope for future generations
Obviously, there is still a long way to go before we see the treatment available everywhere in pharmacies. The next crucial step is currently taking place in mice. The goal is to determine when is the ideal time to intervene, and if it is possible to do it in utero.
The challenge is also to see if extinction – even partial – of the chromosome is enough to significantly improve the cognitive abilities and overall health of patients. Parallel studies suggest that a small portion of the XIST gene could be sufficient, which would greatly facilitate its transport to brain cells, which are often difficult to access for conventional therapies. We are talking here about transforming a serious genetic condition into a manageable, even invisible pathology on a daily basis.
For parent associations and families, this news is received as an immense relief, proof that research has not forgotten them. If Down syndrome is part of the identity of many patients, the possibility of offering them a longer life (the life expectancy of those affected is 60 years) and, above all, more comfortable is a powerful motivation for the medical profession. Science does not seek to erase difference, but to give everyone the same chances.
Although caution remains in order, as with any major medical advance, optimism is real and the foundations for chromosomal therapy have been laid. As the research team states in the journal PNAS, this work could one day make chromosomal diseases a mere memory.
