TP53 and embryonal neoplasm: In contrast, survival for medulloblastoma (a high-grade embryonal tumour) varies largely between and within [5, 27] (< 50–90% 5-year survival) [33] the principal four molecular subgroups recognized in the World Health Organisation (WHO) 2021 classification; WNT (wingless)-activated, SHH (sonic hedgehog)-activated and TP53-mutated, SHH-activated and TP53-wildtype and non-WNT/non-SHH (consisting of the so-called Group 3 and Group 4 classes) [13, 22, 39].