Pathogenic variants in SMARCE1 and another five genes (SMARCB1, SMARCA4, SMARCA2, ARID1A, and ARID1B) encoding subunits of the switch/sucrose non‐fermenting (SWI/SNF) ATP remodeling complex cause CSS (Miyake, Tsurusaki, & Matsumoto, 2014) which is a rare congenital syndrome characterized by developmental delay, moderate to severe intellectual disability, hypoplasic or absent fifth fingernails or toenails, distinctive facial features, hypertrichosis, sparse scalp hair, and hypotonia (Kosho & Okamoto, 2014; Santen et al., 2013; Tsurusaki et al., 2014; Zarate et al., 2016). Here, SMARCA2 is linked to Coffin-Siris syndrome.