The Tumor Biomarker Series: 1p/19q co-deletion

Allelic losses on chromosomes 1p and 19q are associated with oligodendroglial phenotype. Most studies have indicated that combined loss of 1p and 19q are specific to oligodendrogliomas, with only a few astrocytomas and a small subset of oligoastrocytomas harboring these alterations. Those oligodendrogliomas with 1p/19q loss show enhanced response to chemotherapy and are associated with prolonged survival. Solitary losses of 1p or 19q are also occasionally noted within an infiltrating glioma, but are not as strongly linked to the oligodendroglioma histologic phenotype and are not predictive of enhanced response to therapy or prolonged survival. Co-deletion of 1p/19q is highly associated with the IDH1 mutation, with over 80% of 1p/19q co-deleted oligodendrogliomas also carrying the IDH1 mutation.