Rett syndrome is a rare inherited disease that causes developmental and nervous system problems, mostly in girls. It's related to autism . Babies with Rett syndrome seem to grow and develop normally at first. Between 3 months and 3 years of age, though, they stop developing and even lose some skills. Symptoms include Loss of speech Loss of hand movements such as grasping Compulsive movements such as hand wringing Balance problems Breathing problems Behavior problems Learning problems or mental retardation Rett syndrome has no cure. You can treat some of the symptoms with medicines, surgery, and physical and speech therapy. Most people with Rett syndrome live into middle age and beyond. They will usually need care throughout their lives.