Hallmark cytogenetic events such as loss of chromosome (chr) 22 in atypical teratoid/rhabdoid tumor (ATRT) (case #30), chr1q gain in CNS neuroblastoma with FOXR2-activation (#01), chr9q deletion in sonic hedgehog (SHH)-activated medulloblastoma (MB) (#5, #43), MYCN amplification in relapsed MB-SHH (#40), and i(17q) in MB Group3/4 (G3/4) (#7, #20, #28) were readily detected in CSF (Fig. 3E) [52–54]. Here, SHH is linked to medulloblastoma.