[Prevalence of Rett Syndrome in Tokyo]

Prevalence of Rett syndrome (RS) was studied in Tokyo. Based on the experience of our pilot study, we chose schools to identify the cases. We visited forty-four schools for mentally/physically handicapped children. The population of girls aged 6-14 years in the area was 598,000 and the number of girls examined at the schools was 1,311. We identified 24 cases with "classical" RS and 6 cases with "variant" RS. About one-third of the cases had not been diagnosed properly. The prevalence of RS was 0.50/10,000 girls age 6-14 years in metropolitan Tokyo, 1 April, 1988, including variants. The rate showed no statistical difference compared to those reported from European countries.