Individuals and their families affected by disorders with a potentially genetic basis within six broad categories will be evaluated over time to characterize the natural and clinical history of various specific disorders. Medical and laboratory evaluations will be completed to identify areas of management concern that have not been previously described. Further protocols will be developed addressing specific disorders once a number of affected individuals have been investigated and is sufficient to query various aspects of those disorders. Issues for both diagnosis and medical management of those affected with certain genetic disorders will be collated and addressed within a national consensus conference format. In addition, phenotype to genotype correlation will be established to further understanding of specific molecular alterations on phenotypic expression. This broad-based protocol will also facilitate the training of fellows in medical genetics, graduate and post graduate training in genetics and genetic counseling.