Its loss‐of‐function mutations or loss have been demonstrated as driving forces for the initiation and development of many cancers like B‐cell lymphoma, melanoma, medulloblastoma, lung, and pancreas cancers.[15, 16, 17, 18, 19, 20, 21] In spite of the well‐established tumor suppressive effect of KMT2D in lymphoma and solid cancers as well as KMT2C and KDM6A encoding components in the COMPASS‐like complex were identified as tumor suppressor genes in AML, the role of KMT2D in myeloid malignancies seems the opposite. The gene discussed is KMT2D; the disease is medulloblastoma.