Patients with cancer but who do not have overgrowth or other non-tumor manifestations of PS or non-PS overgrowth, whose tumors may harbor AKT1, PIK3CA, or other mutations, are not eligible for this study. In general, patients who clearly meet diagnostic criteria for a well-characterized overgrowth syndrome that is NOT PS are not eligible for this study. Bannayan-Riley-Ruvalcaba syndrome and PHACES syndrome are examples of such entities. We have no plans to enroll prisoners, fetuses, pregnant women, healthy volunteers, or lab personnel. Some persons with PS and other overgrowth conditions are intellectually disabled (ID) or developmentally delayed (probably ~10%). The consent issues are no different for children with ID than developmentally appropriate children except that assent will be judged by developmental level instead of age. Probands who are adults and decisionally-impaired are eligible only if they have a legal guardian who has authority to sign a consent form on their behalf. Patients who are medically fragile or unable to tolerate travel to the NIHCC will not routinely be eligible for participation.