Intriguingly, in contrast to group 3 and group 4 medulloblastomas, overexpression and focal gain of OTX2 are usually not observed in type 2 tumours, where the Shh pathway is overactivated, even though this subtype is known to originate from GCPs14,15,19,21,22. The gene discussed is OTX2; the disease is medulloblastoma.