Oligodendrogliomas usually show specific genetic alterations that can distinguish them from other types of gliomas. The most common genetic alteration in oligodendroglioma is a heterozygous deletion of the long arm of chromosome 19 (19q) with an incidence of 75%-80%. The prevalence of the combined deletion of 1p and 19q is about 60-70%. This deletion is uncommon in other types of gliomas, especially astrocytomas. Olig1 and Olig2 are family genes of oligodendroglial cells and are expressed not only in adult cells but also in oligodendroglial cell precursors, and their expression is specific. Glioblastoma, especially for differential diagnosis.