This study will examine rare congenital disorders that involve malformations and abnormal growth. It will focus on patients with Proteus syndrome, whose physical features are characterized by overgrowth, benign tumors of fatty tissue or blood vessels, asymmetric arms or legs, and large feet with very thick soles. The study will explore the genetic and biochemical cause and course of the disease, the changes in symptoms over time, and the effects of the disease on patients.