SHH and medulloblastoma: While the WNT and SHH subgroup can be clearly identified based on the WNT and SHH signaling pathway mutations, much less is known about Group 3 and Group 4 tumors, and these subgroups remain as non-SHH/non-WNT medulloblastomas in WHO’s 2016 classification for diagnostic considerations (Louis et al., 2016).