1p & 19q codeletion:
Complete deletion of both the short arm of chromosome 1 (1p) and the long arm of chromosome 19 (1p & 19q codeletion). 1p/19q co-deletion is the molecular genetic signature of oligodendrogliomas, a subtype of primary brain tumours accounting for approximately ten to fifteen per cent of all diffuse gliomas in adults.
1p & 19q as the diagnostic barrier in glioma:
1p/19q co-deletion is a pathognomonic biomarker that defines a distinct glioma entity five and is characteristic of oligodendrogliomas. Virtually, all 1p/19q co-deleted oligodendrogliomas have a mutation in isocitrate dehydrogenase 1 (IDH1) at arginine 132 (R132) or the analogous residue arginine 172 in IDH2 (R172).
Other common molecular alterations co-occurring with 1p/19q co-deletion include mutations in the telomerase reverse transcriptase (TERT) gene promoter, mutations in a homolog of Drosophila capicua (CIC) and far upstream element-binding protein (FUBP1).
Significance of Complete 1p/19q codeletion:
The histopathological diagnosis of diffuse gliomas often lacks the precision that is needed for tailored treatment of individual patients. Assessment of the molecular aberrations will probably allow more robust and prognostically relevant classification of these tumours. Markers that have gained a lot of interest in this respect are co-deletion of complete chromosome arms 1p and 19q, (hyper)methylation of the MGMT promoter and IDH1 mutations.