Features include: apparently normal development for the first few months, then psychomotor deterioration, absent or defective speech, lack of facial expression, seizures, characteristic walk, persistent and bizarre movements of the hands, raised ammonia levels, loss of previously acquired skills, resulting in severe learning difficulty. Slowly progressive with continued deterioration. All reported cases have been female. X-linked dominant inheritance.
A developmental disorder in the pervasive developmental disorders category of the DSM-IV which occurs only in females. Rett Syndrome is characterized by normal development for the first six months followed by a gradual loss of purposefull hand movements with accompanying stereotypic hand movements, loss of general motor skills, a deceleration in head growth, ataxia, and marked delay and impairment of language development.