"Prader-Willi Syndrome: Switching On Silent Genes Offers a New Path to Treatment"

Researchers at the Walter and Eliza Hall Institute of Medical Research (WEHI) in Australia have found a way to switch healthy genes back on in Prader-Willi syndrome, a rare genetic condition that affects about 400,000 people worldwide. In a study published on 27 October 2026 in the journal Science Advances, the team showed that removing a protein called SMCHD1 lifts a genetic "brake" that keeps healthy genes silent, restoring their activity in patient-derived stem cells and in animal models. The discovery is being developed toward potential new medicines by WEHI spinout company Togglelux Therapeutics.

Prader-Willi syndrome is one of the most demanding conditions a family can live with. It affects the brain and development, causing developmental delays and intellectual disability, and it drives an insatiable appetite that can lead to obesity and life-threatening complications. Families today manage it with a patchwork of medications, surgeries and specialist appointments, and the head of the Prader-Willi Research Foundation Australia, Kathlene Jones, describes children and adults navigating a world full of food they cannot eat while feeling an intense drive to consume it. Every existing treatment addresses symptoms. None addresses the cause.

The cause, in outline, is a silencing problem. In Prader-Willi syndrome, certain genes essential for development and brain function are switched off when they should be on. SMCHD1, a protein first discovered at WEHI in 2008, helps regulate gene activity, and in this condition it is part of the machinery that keeps those genes dormant. The new study combined CRISPR gene-editing, stem-cell and genomic technologies to track what happened across thousands of genes when SMCHD1 was removed, measuring the effects in the most disease-relevant brain tissue. Lead researcher Marnie Blewitt, WEHI's deputy director and head of its epigenetics laboratory, said the team had long thought reactivation might be possible, but did not know whether it could be done safely. The answer, in cells and animals at least, was yes: gene activity came back without causing problems elsewhere in the body.

That safety result is the real news here, and it is worth being precise about why. Many genetic strategies fail not because the target gene stays off but because switching it on disturbs everything around it. A treatment meant for babies and young children cannot afford that kind of collateral damage, and Blewitt's team frames the finding exactly that way: the strongest evidence so far that removing SMCHD1 can restore lost gene activity without disrupting the rest of the body. It is also the culmination of nearly two decades of work on a protein her team discovered, which is a useful reminder that the discoveries that look sudden in a headline usually are not.

Honesty requires the other half of the story. This is still early-stage, preclinical research. There is no drug yet, no announced human trial, and no timeline from Togglelux for one. The distance between genes waking up in patient-derived cells and a safe medicine for a child is measured in years of delivery, dosing and toxicity work, and most programs that start this journey do not finish it. What makes this one worth tracking is the combination: a defined molecular target with a demonstrated safety signal in models, a dedicated spinout company to carry it forward, and a patient community organized enough to push it. I expect that combination to produce a registered clinical trial of an SMCHD1-targeting therapy for Prader-Willi syndrome by the end of 2028, and I put that at 40%: better than a coin flip against the usual attrition of early drug programs would be dishonest, but this program has cleared the first hard question, which was whether the genes could be woken at all without breaking something else. If no trial is registered by then, the likeliest reason will be the ordinary one: turning a laboratory brake-release into a deliverable drug took longer than the science suggested, not that the biology was wrong.