This gene is a tumor suppressor that is implicated in the phosphoinositol 3-kinase (PI3K/AKT) pathway, and is involved in the regulation of growth, associated with Cowden-1 syndrome (OMIM 15835) and Bannayan–Riley–Ruvalcaba syndrome (OMIM 15348) [48]. The gene discussed is PIK3CA; the disease is Cowden syndrome 1.