Germline PTEN mutations, inherited with an autosomal dominant mechanism, have been related with the etiology of “PTEN hamartoma tumor syndromes” (PHTS), which include Cowden syndrome (CS, OMIM 158350), Bannayan-Riley-Ruvalcaba syndrome (BRRS, OMIM 153480) and PTEN-related proteus syndrome (PS, OMIM 176920) [1–5]. The gene discussed is PTEN; the disease is Cowden syndrome 1.