Rett Syndrome is not a common disorder, but it is a devastating one. It is a neurological developmental disorder and is classified as a particularly extreme form of autism. But, unlike most forms of autism, it almost exclusively shows up in girls.
Also unlike other forms of autism, researchers have been able to pinpoint the cause of the disorder — a mutation on the MeCP2 gene, carried on the X chromosome. And scientists at the Fred Hutchinson Cancer Research Center are on a mission to find out how they can re-activate healthy versions of the gene to treat the disease.
In a paper published today in the Proceedings of the National Academy of Sciences, Fred Hutch researchers report that they found a mechanism that could be used to treat Rett Syndrome, and possibly other diseases which are impacted by “silenced” genes — including cancer.
Here’s how a potential Rett Syndrome therapy would work: because female DNA has two X chromosomes, with the same genes on each, one is active and one is silenced in each cell. In girls that have Rett, only one of their X chromosomes carry that mutated gene, so about half of their active chromosomes carry it while half are normal.
“What we are trying to do here is to reactivate the silenced copy of the MeCP2 gene,” said Antonio Bedalov, a researcher at Fred Hutch who led the study.
Bedalov’s lab is focused on epigenetics: the study of how changes in a chromosome can change gene expression without changing the gene itself. In this study, he worked on mouse cells that carried the mutated gene.
“Our results are interesting from a biological standpoint and science standpoint, but also from a therapeutic one,” he said.
“We have identified a set of 30 genes, of which most than half encodes for proteins that can easily serve as therapeutic targets,” he said. These protiens are in charge of silencing portions of the X chromosome, meaning that removing them will remove some of the silencing effect that makes the healty gene inactive.
“That gives us hope that we can then reactivate the silenced copy of MeCP2,” thus reversing or limiting the effects of the mutated gene, he said.
Bedalov emphasized that treatment or a cure is still far off, but the results of the study get closer to one than ever before. And they could have important long-term impacts on how we understand and are able to manipulate silenced genes.
Bedalov said they also encountered two potential problems to using this method as a therapy for Rett: first, the genes were only partially awakened, and second, the process also awakened genes on either side of the target gene.
He said these issues will be examined more closely in the current study he is running, using mice to test the approach in-vitro.
The study was supported by the Rett Syndrome Research Fund, which finances research into the disorder across the world.