**4. Glioblastoma multiforme risk factors**

GBM is the most aggressive form of malignant glioma. Several syndromes are associated with the increased incidence of GBM, such as Lynch syndrome, Li–Fraumeni syndrome, melano‐ ma–neural system tumor syndrome, Ollier disease, and Maffucci syndrome [16]. A small proportion (5–10%) of patients has a family history of glioma. Genes too exist that are involved in gliomagenesis and participate in glioma growth, such as telomerase reverse transcriptase (TERT) [17], *EGFR* [18,19], coiled‐coil domain containing protein 26 (*CCDC26*) [20],Cyclin‐ dependent Kinase inhibitor 2B [17], *TP53* [21,22,23], and the regulator of telomere elongation helicase 1 (*RTEL1*) [24,25].
