[Rett syndrome--case report].

We report on a 13 years old girl with Rett syndrome (autism, dementia, ataxia and loss of purposeful hand use in girls). The Rett syndrome is unexpectedly frequent (1:15,000 in 1-14 years old girls). The diagnosis is based solely upon clinical development observation. Typical false diagnoses are: autism, some types of epilepsia, deprivation, cerebral palsy, degenerative encephalopathy, infantile psychosis and types of ataxia. The etiology is unknown, genetic factors, possibly an X-linked dominant new mutation, explain many, but not all findings. The empiric recurrence-risk is apparently low.