No abstract

Naltrexone may modify some of the respiratory disturbance in Rett syndrome. Declines in motor function and more rapid progression of the disorder suggest a deleterious effect.

The Texas Rett Syndrome Registry maintains the largest population-based registry of cases and potential cases of Rett syndrome in the world. The most precise estimate of the prevalence of Rett syndrome of 1 per 22800 (0.44/10000) females aged 2 through 18 years of age was generated from this Registry. In addition, the first prevalence figures for black and Hispanic female cases were estimated. Registry cases are actively ascertamed from multiple sources. Registry staff identify presumptive cases from review of information provided to the Registry by the parent or guardian. Preliminary diagnostic evaluation includes standardized review of medical records and videotape of key behaviors. Diagnosis is confirmed at clinical evaluation. The active surveillance system is monitored with the two-source capture-recapture methodology and case ascertainment is projected. The 1990 prevalence estimate of Rett syndrome indicates that the syndrome occurs less frequently than previously estimated. Until a biologic marker for Rett syndrome is identified or a standard definition for an incident case of Rett syndrome is designated, the prevalence of Rett syndrome will remain a major investigative issue of its epidemiology, and the Registry will be an important, systematic mean to gather case material for clinical and laboratory studies providing the foundation for the development of preventive interventions.

No abstract

Evidence suggests that Rett syndrome is a genetic disorder; however, an etiologic genetic model has yet to be identified. The purpose of this study was to apply a statistical model, Sartwell's incubation period model, to estimate the incubation period of Rett syndrome and postulate further on the etiology of Rett syndrome. Sartwell's model was used to test the hypothesis that the age of onset of developmental regression distributions approximate a logarithmic normal model and thus the etiologic factors of Rett syndrome occur in utero or prior to conception. Data from three case-series of Rett syndrome from different geographic regions were used for the analyses. Curves resulting from the analyses demonstrated a good approximation to the logarithmic normal distribution, indicating a good fit of the data to Sartwell's model. In conclusion, the incubation period of Rett syndrome fits the logarithmic normal model, which is consistent with the theory that a major causal factor for Rett syndrome most likely occurs in utero or prior to conception, eg, a defective gene.