RAD21 and Pierpont syndrome: Because WDSTS can phenotypic overlap with Pierpont syndrome, Cornelia De Lange syndrome and Kabuki syndrome [6, 7, 9, 19, 20], the candidate genes causing the later three syndromes (i.e. TBL1XR1, NIPBL, SMC1A, SMC3, RAD21, HDAC8, KMT2D, and KMD6A) in our cohort have been excluded.