Menke-Hennekam syndrome (MKHK) is a novel syndrome caused by mutations in CREBBP and EP300. Although mutations in the same genes cause Rubinstein-Taybi syndrome [DS:H00504], MKHK patients didn't show the characteristics typical for Rubinstein-Taybi syndrome. The main characteristics of the MKHK are developmental delay, autistic behavior, short stature, and microcephaly.