PIK3CA and Proteus syndrome: Human disorders caused by activating mutations in the PI3K-AKT pathway constitute a large group of diseases including Proteus syndrome (OMIM #176920), PIK3CA-related overgrowth spectrum (OMIM #612918), megalencephaly-polymicrogyria-polydactyly-hydrocephalus (MPPH; OMIM #PS603387) syndrome and others.