Clinical Trials in Rett Syndrome: Potential for Early Intervention (An International Workshop) to be held at the Inn at the Colonnade in Baltimore, June 30-July, 2005, is proposed. The objectives of the workshop are: (1) to assess the present state-of-the-art research in clinical trials and early intervention in Rett syndrome (RTT), (2) to provide a forum for an active exchange of scientific information, regarding RTT diagnosis and treatment, between participants representing major RTT research centers throughout the world, (3) to identify areas in which current knowledge is limited, and (4) to provide recommendations as well as to stimulate future research on clinical trials, and related issues, in RTT. Topics to be covered by the workshop include: (1) Neuroscientific bases of RTT treatment, (2) early identification of RTT, (3) physiologic, neurologic, neuroimaging, and behavioral outcome measures, (4) pharmacological and non-pharmacological interventions, (5) experience in clinical trials in RTT, and (6) genetic and other specific issues in clinical trials in RTT. RTT is a severe developmental disorder, affecting predominantly females and characterized by cognitive impairment, autistic behavior, stereotypic movements, and respiratory irregularities. The demonstration of mutations in the coding region ofMeCP2, as the genetic abnormality associated with 60-80% of RTT patients, has initiated a new era of clinical and neurobiologic research on this disorder. Of the small number of reported clinical trials in Rett syndrome (RTT), only an ongoing study of folate and betaine takes advantage of this new genetic information. Consequently, the proposed workshop is quite timely. The format of the conference will promote discussion of the topics, by adding to the formal presentations two concluding roundtables. An expected outcome of this workshop is the development of new research projects, including multi-center collaborations, which will advance the area of clinical trials in RTT. Proceedings of the conference will be published in a neurology journal and a report will be communicated 1:0 public and private funding agencies.