In glioma, tumour grade IV is positively associated with the number of intronic junctions per sample (P = 1.1 × 10−5), whereas tumour grade II (P = 2.9 × 10−8) and presence of IDH1 mutation (P = 0.8 × 10−3) were negatively associated. The gene discussed is IDH1; the disease is central nervous system cancer.