Common genetic changes and tumor associated mutations found in higher grade gliomas, p53, PDGF, p16 (CDKN2A), IDH1 and IDH2 are rarely reported in pilocytic astrocytomas, which is consistent with our results that also indicate a lack of focal abnormalities in loci where those genes reside. The gene discussed is CDKN2A; the disease is central nervous system cancer.