PTEN and glioma: One of the most common alterations associated with transformation of lower grade to GBM IDHmut gliomas was the loss of chromosomal regions surrounding PTEN. IDHmut GBM tumors demonstrated significantly higher levels of overall CNAs compared to lower grade IDHmut tumors and all grades of IDHwt tumors, and IDHmut GBMs also demonstrated significant increase in incidence of chromothripsis.