We therefore suggest that the genetic testing of young patients with medulloblastoma should include the PTEN gene in addition to the APC, BRCA2, PALB2, PTCH1, SUFU and TP53 genes with well‐defined associations to medulloblastoma to characterize the role of PTEN in the development of medulloblastoma. The gene discussed is APC; the disease is medulloblastoma.