PTEN and PTEN hamartoma tumor syndrome: Germline PTEN mutations have been reported in up to 60% of BRRS patients.10–14 Among those who remain mutation negative, approximately 10% were found to harbor large deletions of PTEN. 14 Such BRRS patients with germline PTEN mutations belong to the PTEN hamartoma tumor syndrome (PHTS), which also includes PTEN-related Cowden, Cowden-like, Proteus, and Proteus-like syndromes.15 Although these conditions are inherited autosomal dominantly, a recent study showed that de novo PTEN mutations occur in at least 10% of molecularly tested PHTS probands,11,12,16–18 including PTEN-related BRRS.19