Further, our findings indicate that TP53 changes and CDKN2A deletions tend to coexist in LGG, suggesting that they are early events in progression of these tumors, as well as CDKN2A and PTEN deletions, since a significant association was observed, with CDKN2A changes preceding PTEN deletions, that are involved with malignant progression of gliomas. The gene discussed is PTEN; the disease is central nervous system cancer.