After the identification of a novel p27 mutation (p27 p.177fs) in a rat model of MEN syndrome, Pellegata and colleagues reported the discovery of a germline nonsense mutation (p.W76*) in heterozygosis in a patient suspected for MEN1 syndrome, but negative for MEN1 mutations (33, 41). The gene discussed is CDKN1B; the disease is multiple endocrine neoplasia type 1.