SHH and pilocytic astrocytoma: As an example, we observed that medulloblastoma samples were split into three distinct clusters that correlated with known Medulloblastoma subtypes13 (Wnt, Sonic hedgehog (SHH) and groups 3,4, Supplementary Fig. 4a). Similarly, Ependymomas (EPN) samples formed several clusters that correlated with the anatomic tumor location (supratentorial (ST)-EPN, spinal-EPN, and posterior fossa (PF)-EPN) 13(Fig. 4a, Supplementary Fig. 4b). Pediatric pilocytic astrocytomas (PAs) and pediatric low-grade gliomas clustered closely together suggesting that they exert similar gene expression patterns.