disorders. Our paradigm is the previous work we have done with Pallister-Hall syndrome (PHS) and Greig cephalopolysyndactyly syndrome (GCPS), where we have successfully used a combined clinical-molecular approach. Using this strategy, we have brought 50-100 patients or families with these disorders to the NIH clinical center (NIH CC) for a comprehensive clinical evaluation with follow-up at a frequency appropriate to the disorder. We have also clinically and/or molecularly evaluated many additional patients with atypical or non-classic presentations of PHS and GCPS and have conducted exploratory studies of other phenotypes to determine how they might fit into the more general models generated to explain PHS and GCPS. We are currently generalizing this approach to a number of disorders including talipes equinovarus, atrial septal defect, Robin sequence, and persistent left superior vena cava (TARP) syndrome. Specimens from patients participating in both the laboratory and clinical arms of the protocol will be collected and evaluated in the laboratory by linkage analysis, physical mapping, candidate gene characterization, mutation screening and targeted exome sequencing, and cell biologic studies of normal and mutant proteins.