Rett's Disorder also called Rett Syndrome refers to a pervasive developmental disorder, occurring only in females, an X-linked dominant neurological disorder that affects only girls
in which the child develops normally until between months and years of age and then begins to show a number of neurological and cognitive impairments, including a deceleration of head growth, stereotyped movements of the hand, a lack of bodily coordination, language impairments, and social withdrawal. It is one of the most common causes of mental retardation in females.
Rett Syndrome was first described by Andreas Rett, an Austrian pediatrician, in 1966.