The inactivation of SMARCB1 has been observed in malignant rhabdoid tumors (MRT), childhood atypical teratoid/rhabdoid tumor (AT/RT) of the central nervous system (CNS), epithelioid sarcoma [2], subsets of collecting duct carcinoma [3] and epithelioid malignant peripheral nerve sheath tumor (MPNST) [4], renal medullary carcinoma [5] and undifferentiated pediatric sarcomas [6], etc. The loss of SMARCB1 nuclear expression is of diagnostic value for renal or extra-renal MRT and AT/RT [7]. Here, SMARCB1 is linked to ataxia telangiectasia.