An MEN1-like clinical picture can be seen in MEN4 syndrome due to mutation in cyclin dependent kinase inhibitors, primarily p27 (CDKN1B) and rarely in p21 (CDKN1A), p15 (CDKN2B), and p18 (CDKN2C) (108, 109). The gene discussed is CDKN2C; the disease is Down syndrome.