EP300 and Rubinstein-Taybi syndrome: Most of the RSTS cases are linked to mutations in the CBP (also known as CREBBP (CREB-binding protein)) (60% of cases) and p300 (EP300) (E1A Binding Protein P300) (3% of cases) genes (Petrij et al., 1995; Roelfsema et al., 2005).