SMARCB1 and cancer: SMARCB1 is also a potent tumor suppressor, being mutated or deleted in nearly all atypical rhabdoid/teratoid tumors (AT/RTs), aggressive cancers that primarily affect the central nervous system and which can be diagnosed at very young ages, even prenatally (Hoot et al., 2004; Pawel, 2018; Negahban et al., 2010).