In Rett syndrome, leaky brain blood vessels traced to microRNA

MIT researchers have discovered that two common genetic mutations that cause Rett syndrome each set off a molecular chain of events that compromises the structural integrity of developing brain blood vessels, making them leaky. The study traces the problem to overexpression of a particular microRNA (miRNA-126-3p), and shows that tamping down the miRNA's levels helps to rescue the vascular defect.