Medulloblastomas, for instance, were initially described as small round blue cell tumours of the cerebellum; however, the discovery of hSNF5/INI1 mutations in atypical teratoid/rhabdoid tumours (ATRTs) and C19MC amplifications in ETMRs have led these tumour types to be recognized as different diseases [173]. This evidence concerns the gene SMARCB1 and atypical teratoid rhabdoid tumor.