Malignant rhabdoid tumors (MRT), also known as extra-renal rhabdoid tumors or rhabdoid tumors of the soft-tissues, are aggressive pediatric cancers characterized by loss of the tumor suppressor SWI/SNF-related matrix-associated actin-dependent regulator of chromatin subfamily B member 1 (SMARCB1) [1]. The gene discussed is SMARCB1; the disease is rhabdoid tumor.