SMARCB1 and neoplasm: Loss of SMARCB1 disrupts activation of the SWI/SNF chromatin remodeling complex, which plays a crucial role in cell differentiation, leading to dysregulation of gene expression and tumor suppression.4 AT/RTs, harboring SMARCB1 alterations, can be subdivided into 3 molecular groups based on DNA methylation profiles: AT/RT-TYR, AT/RT-SHH, and AT/RT-MYC.