PTEN and Cowden syndrome 1: PTEN hamartoma tumor syndrome (PHTS) is caused by germline autosomal-dominant mutations of the tumor suppressor gene PTEN. PHTS encompasses different syndromic disorders including Cowden syndrome (CS), Bannayan Riley Ruvalcaba Syndrome (BRRS), Lhermitte Duclos Syndrome, Proteus and Proteus like syndrome.