CHEK2 and neoplasm: Although previous studies reported no or low frequency of Chk2 mutations (approx. 6%) [139,140], 22% of glioma patients in the TCGA study presented single-copy loss of the chromosomal region containing Chk2, with a significant reduction of Chk2 mRNA, suggesting that it might represent an important tumor suppressor in a subset of glioma patients [1,132].