PTEN and Cowden disease: This finding discredited theory proposed earlier in the 21st century that the Phosphatase and TENsin (PTEN) hamartoma syndrome (also known as Cowden syndrome or Bannayan–Riley–Ruvalcaba syndrome) and PS had the same cause.22, 23Current understanding reveals that loss-of-function mutations in PTEN (located on 10q23.3) activate AKT1, leading to certain shared features with PS.