SHH and medulloblastoma: SHH medulloblastomas show unregulated ligand-independent SHH pathway signaling due to mutations/alterations such as loss-of-function of PATCHED (PTCH1) or Suppressor of Fused (SUFU), gain-of-function of Smoothened (SMO), GLI1, GLI2, or MYCN, and/or other alterations41–43.