[Studies on the Rett syndrome. Part 1. Prevalence of the Rett syndrome].

The Rett syndrome (RS) is currently diagnosed by its characteristic clinical features and course since specific biochemical markers have not been established. These features include psychomotor regression after early periods of normal development, autistic appearances, hand stereotypy and loss of purposeful hand skills. Since these features may be seen in other children with neurological disorders, it is possible that many patients admitted to residential facilities or schools have RS but have not been diagnosed as such. We undertook a survey of the schools and residential facilities for handicapped children at Tokushima Prefecture to determine the prevalence of RS in the Japanese. The prevalence of RS in Tokushima prefecture was 0.36/10,000 girls at age 15 and under (0.37/10,000 girls at 7-15 years). The prevalence of RS in our study was lower than the European studies.