SHH and medulloblastoma: In fact, a radical paradigm shift has been observed in medulloblastoma research since the 2016 WHO Classification of Tumors of the Central Nervous System, which divided medulloblastomas into four molecularly stratified subgroups: wingless (WNT) activated, sonic hedgehog (SHH) activated, group 3, and group 4 [4] (Table 1).