The concept of PTEN hamartoma tumor syndrome (PHTS [OMIM 158350]) was proposed to encompass any clinical disorder with germline PTEN mutation on molecular genetic testing, regardless of phenotype.7,8 Based on this broad clinical spectrum and unified genetic etiology, PHTS serves as a useful disease model to identify modifiers of variable heritable disease risk at the individual level. Here, PTEN is linked to PTEN hamartoma tumor syndrome.