Brothers with germline PTEN mutations and persistent hypoglycemia, macrocephaly, developmental delay, short stature, and coagulopathy.

Phosphatase and tensin homologue deleted in chromosome 10 (PTEN) has dual protein and lipid phosphatase activity, and its tumor suppressor activity is dependent on its lipid phosphatase activity, which negatively regulates the phosphatidylinositol 3-kinase/Akt pathway. Mutations in PTEN have been identified in different clinical disorders such as Bannayan-Riley-Ruvalcaba syndrome, Cowden syndrome, Proteus syndrome, Proteus-like syndrome, and autism spectrum disorders with macrocephaly (Hobert). The absence of clear genotype-phenotype correlations between these syndromes appears to represent age-related manifestations of the same condition, which shows variable expressivity. Here, we present two siblings whose phenotypes were extremely variable compared with the original descriptions of the syndromes associated with PTEN germline mutations. Our patients present with a unique constellation of features that have not yet been described in humans with PTEN germline mutations, some of which have not been described in the same individual, like severe hypoglycemia, growth hormone deficiency, Von Willebrand disease, and dyslipidemia.