Disruptions in the regulation of PTEN by a range of molecular mechanisms can generate various dysfunctional PTEN species and/or a spectrum of PTEN levels that can variously contribute to the pathogenesis of inherited syndromes, including Cowden disease, Lhermitte-Duclos syndrome, Bannayan-Zonana Syndrome [38], cancers, and other diseases. The gene discussed is PTEN; the disease is Cowden syndrome 1.