Diagnostic workflow combining MLPA and WES was carried out to identify causative genetic alterations in CREBBP and EP300. Four of the five patients were found to harbor causative mutations in CREBBP. As the exact pathogenesis of RSTS has yet to be completely elucidated and genetic alterations in roughly 20% of the patients have yet to be found, more research is needed on the roles of genetic and epigenetic alterations in RSTS. Here, EP300 is linked to Rubinstein-Taybi syndrome.