Rett syndrome

Rett syndrome is a progressive neurological disorder in which individuals exhibit reduced muscle tone, autistic-like behavior, hand movements consisting mainly of wringing and waving, loss of purposeful use of the hands, diminished ability to express feelings, avoidance of eye contact, a lag in brain and head growth, gait abnormalities, and seizures. Hypotonia[?] (loss of muscle tone) is usually the first symptom. The syndrome affects approximately 1 in every 10,000-15,000 live female births, with symptoms usually appearing in early childhood — between ages 6 and 18 months. Rett syndrome is caused by mutations (structural alterations or defects) in the MECP2 (pronounced meck-pea-two) gene, which is found on the X chromosome. Scientists identified the gene — which is believed to control the functions of several other genes — in 1999.

There is no cure for Rett syndrome; however, there are several treatments options. These include treatments for the orthopedic and learning disabilities and seizures that may occur in individuals with Rett syndrome. Some children may require special nutritional programs to maintain adequate weight.

In spite of the severe impairments that characterize this disorder, the majority of individuals with Rett can be expected to reach adulthood, surviving at least into their 40s. However, the risk of death is increased. Sudden, unexplained death — possibly from brainstem dysfunction with respiratory arrest — often occurs.

Based on http://www.ninds.nih.gov/health_and_medical/disorders/rett_doc.htm