SWI/SNF-related, matrix-associated, actin-dependent regulator of chromatin, subfamily a, member 4 (SMARCA4) is one of the most frequently mutated chromatin-remodeling ATPases in the SWI/SNF complex and acts as a tumor suppressor gene in cancer [2]. SMARCA4 germline mutations are evident in almost all infant rhabdoid tumor predisposition syndrome-2 (RTPS2) and congenital multiple malformation syndrome (Coffin-Siris syndrome), approximately 35% of rhabdoid tumors, and approximately 50% of small cell carcinoma of the ovary, hypercalcemic type (SCCOHT) [3]. The gene discussed is SMARCA4; the disease is ovarian small cell carcinoma.