IDH1 and central nervous system neoplasm: When LGG patients were classified into three groups (IDH1 wild-type, IDH1 mutations with 1p19q codeletion, and IDH1 mutations without 1p19q codeletion) according to the guideline of the 2016 WHO classification of CNS tumors, the group of IDH1 wild-type (n = 116) had the worst OS (median survival: 2.123 years; five-year survival rate: 32.9%), and the group with IDH1 mutations and chromosome 1p19q codeletion (n = 155) had the best OS (median survival: 12.863 years; five-year survival rate: 78.2%) (Figure 3C).