RSTS type 1 (RSTS1) is caused by deletions or pathogenic variants in CREBBP and accounts for approximately 50%–60% of individuals with RSTS (Petrif et al., 1995; Bartsch et al., 2005; Fergelot et al., 2016; Stevens, 2019). The gene discussed is CREBBP; the disease is Rubinstein-Taybi syndrome due to CREBBP mutations.