In diffusely infiltrating gliomas, mutations in MMR genes may occur as part of a germline syndrome [28, 59, 75, 84, 105, 106, 161, 200], as sporadic mutations [27, 32, 179, 209], or as the result of temozolomide therapy, either due to the selection of temozolomide-resistant MMR-deficient clones or by temozolomide-induced mutation in one of the MMR genes [6, 17, 31, 45, 53, 94, 104, 179, 209, 213, 233]. The gene discussed is MRC1; the disease is central nervous system cancer.