SHH and medulloblastoma: Medulloblastomas are currently divided into four histologically distinct entities (classic, desmoplastic/nodular, extensive nodularity, and large cell/anaplastic) and four genetically defined subgroups (WNT-activated, SHH- activated TP53-wildtype, SHH-activated TP53-mutant, and non-WNT/non-SHH) [31].