IDH1 and astrocytoma (excluding glioblastoma): Our knowledge is expected to increase thanks to amplification of genes such as EGFR in glioblastoma, loss of alleles on chromosomes 1p and 19p in oligodendroglioma, and mutations in genes such as in p53 and IDH1 in low-grade astrocytoma that progresses to malignant astrocytoma.