How does Rett syndrome differ from autism?
Mutations in the MECP2 gene are found in Rett syndrome and have also been identified in some girls with autism, so they are branches of the same tree. While Rett occurs primarily in girls, autism occurs much more frequently in boys. In both conditions, there is loss of speech and emotional contact. However, features seen in Rett and not in autism include deceleration of the rate of head growth and loss of purposeful hand skills and mobility. While hand flapping is seen frequently in autism, the wider range of compulsive purposeless hand stereotypies common to Rett are not seen in autism. The girl with Rett almost always prefers people to objects, but the opposite is seen in autism. Unlike those with autism, the girl with Rett syndrome often enjoys affection. While girls with Rett syndrome often have autistic tendencies at an early age, these features decrease over time.
