SMARCB1 and ataxia telangiectasia: World Health Organization (WHO) defines atypical teratoid/rhabdoid tumour (AT/RT) as a highly malignant central nervous system (CNS) tumour predominantly manifesting in young children, typically containing rhabdoid cells, often with primitive neuroectodermal cells and with divergent differentiation along epithelial, mesenchymal, neuronal or glial lines; associated with inactivation of the integrase interactor (INI)1/hSNF5 gene in virtually all cases [1].