The initial determination of eligibility is made by review of prior clinical records. Some patients are not characterized in sufficient detail to know if the person meets the clinical criteria, yet we may suspect the diagnosis. In those cases, the subjects are brought to NIH and undergo clinically appropriate testing to make the diagnosis. If that clinical testing does not confirm the diagnosis, the patient or parents are given appropriate clinical counseling and returned to the care of their personal physician. If features later develop that allow the diagnosis to be made, they may re-enroll and undergo further evaluation.