Four consensus molecular subgroups—WNT (MBWNT), SHH (MBSHH), group 3 (MBGroup3), and group 4 (MBGroup4)—are now recognised and underpin the 2016 WHO classification of medulloblastoma (genetically defined as WNT-activated; SHH-activated and TP53-mutant and SHH-activated and TP53-wildtype; and non-WNT and non-SHH [group3 and group4]).1 The gene discussed is TP53; the disease is medulloblastoma.