Patients with unusual or unknown conditions that have or have not been diagnosed may be eligible for this screening study. Specific medical criteria for enrollment vary with the particular protocol for which the individual is being screened. Medical and dental histories will be obtained and participants will have a dental examination. Diagnostic procedures will be done in accord with standard medical and dental practice and may include X-rays, blood tests, and routine urinalysis, as appropriate. Participants found eligible for an active study may enroll in that study. Those who are not eligible for a current study may be re-evaluated for future studies within a year if they wish. After 1 year, participants for whom no appropriate studies are identified will be referred back to their primary doctor or referring physician or dentist.