P190 – 2307: Epidemiological study of Japanese Rett syndrome

Abstract

Objective It has known that a prevalence of Rett syndrome (RTT) is approximately 1.0 per 10,000 females. However, we have never Japanese data. In 2010, the recent revised criterion for diagnosis of RTT was published. Here, we performed nationwide survey of RTT, according to the new criterion, to clarify the Japanese epidemiology of RTT. Methods We selected 1,020 hospitals or institutes by stratified sampling from 2,918 ones specialized for pediatrics and pediatric neurology in Japan. We sent the first questionnaire to them to ask the number of RTT patients each institute followed from 2008 to 2009. After responded, we asked clinical details with the second questionnaire. Results We received 677 responses from 1,020 hospitals (total response rate: 66.4%), and they counted 480 definite RTT patients and 79 atypical patients. The estimated total number of definite RTT patients was 1011 (95% confidential interval, 778–1244), and the estimated prevalence of RTT patients in Japan was 0.90 per 10,000 girls. It revealed the local clustering of hospitals, which provide the medical service for RTT patients. Interestingly, over 80% of five main symptoms appeared in typical RTT patients until 3 year-old. Conclusion This is the first nationwide survey of RTT in Japan. It gave a prevalence of concomitant with previous studies in other countries. We have established the clinical and genetic database of Japanese RTT patients. Next, we have to use the database for clinical research to explore biological markers and treatment, with or without international collaborations.