Importantly, all cases predicted to be WNT-driven medulloblastomas by molecular subgrouping had an exon 3 mutation in CTNNB1, and no CTNNB1 mutation was found in a non-WNT medulloblastoma (specificity = 1.000; 95 % CI 0.977–1.000 and sensitivity = 1.000; 95 % CI 0.782–1.000 when considering CTNNB1 mutation status as the “gold standard”, Fig. 2b). The gene discussed is CTNNB1; the disease is medulloblastoma.