EP300 and Cornelia de Lange syndrome: Several reasons are being postulated for the lower detection rate of EP300 mutations: a lower mutation rate; underdiagnosis at similar mutation rates following the generally milder phenotype in cases of RSTS with EP300 mutation; or misdiagnosis in cases with severe phenotype resembling other syndromes with congenital malformations such as Cornelia de Lange syndrome (CdLS) which interestingly is caused by alterations in other chromatin associated proteins [1, 9, 13, 17].