Rett syndrome in Australia: A review of the epidemiology

ObjectiveTo examine the prevalence, cumulative incidence, and survival in an Australian cohort with Rett syndrome (RTT).Study designThe Australian Rett Syndrome Database is a longitudinal data collection that included 276 verified female cases at the end of 2004. Survival was calculated using the Kaplan-Meier product limit method, and cumulative incidence was determined using the complement of the Kaplan-Meier method.ResultsMost cases (88.4%) have had MECP2 mutation testing, with positive results in 73%. The prevalence of RTT was .88 per 10,000 females in 5- to 18-year-olds, and the cumulative incidence was 1.09 per 10,000 females by 12 years of age. The cumulative incidence by the age of 5 years increased from .39 per 10,000 in the 1980 to 1984 cohort to .76 per 10,000 in birth cohorts beyond 1984. Survival was 77.8% at 25 years, compared with 99.96% survival in the Australian female population. Pneumonia (10/25) was the most common cause of death.ConclusionsThe availability of genetic testing has contributed to the changing pattern and timing of RTT diagnosis in Australia. Girls with RTT have worse survival compared with the general female population. When more data are available, it will be possible to evaluate the relationship between survival and specific MECP2 mutations.