Support for polygenic susceptibility to glioma has come from genome-wide association studies (GWASs) that have identified single-nucleotide polymorphisms (SNPs) at eight loci influencing glioma risk—3q26.2 (near TERC), 5p15.33 (near TERT), 7p11.2 (near EGFR), 8q24.21 (near CCDC26), 9p21.3 (near CDKN2A/CDKN2B), 11q23.3 (near PHLDB1), 17p13.1 (TP53) and 20q13.33 (near RTEL1) (refs 6, 7, 8, 9, 10). This evidence concerns the gene RTEL1 and central nervous system cancer.