PTEN and brain cancer: Defects in TSC1, hamartin, has been proven to induce mTORC1 activity, which in turn triggers glioma development when combined with other oncogenic signals (Yamada et al., 2014), such as variations in the known tumor suppressor genes PTEN, TP53, and RB1. Biallellic germline mutations of MUTYH have primarily been related to colorectal adenomas, but a recent report states that monoallelic germline MUTYH mutations may induce an increase in the risk of malignant brain tumors (Kline et al., 2016).