Any Rubinstein-Taybi syndrome in which the cause of the disease is a mutation in the EP300 gene. The disease is MONDO_0013364 (Rubinstein-Taybi syndrome due to EP300 haploinsufficiency). Also known as: EP300 Rubinstein-Taybi syndrome, Rubinstein-Taybi syndrome caused by mutation in EP300, Rubinstein-Taybi syndrome type 2.