1P 19Q Codeletion

From Surgery Encyclopedia

1p 19q codeletion means that there is a combined loss of the short arm of chromosome 1 (i.e. 1p) and the long arm of chromosome 19 (i.e. 19q). It is a genetic marker for Oligodendrogliomas (pathognomonic for oligodendroglioma)

Important Points[edit | edit source]

1p/19q Codeletion
1p/19q Codeletion
  • It is a tie-breaker’ to distinquish oligo- from astrocytomas
    • IDH positive + 1p19q codeletion = oligodendroglioma
    • IDH positive + no 1p19q codeletion = astrocytoma
  • It indicates favorable prognosis
  • It is associated with better chemosensitivity (increased response to chemotherapy)
  • It is due to Loss of one arm of a hybrid chromosome is called loss of heterozygosity (LOH)
  • This is tested using FISH (fluorescence in situ hybridization)

What is the Incidence of 1p/19q codeletion in Oligodendrogliomas?[edit | edit source]

  • Codeletion of 1p and 19q occurs in up to 70% of oligodendrogliomas. [1] [2]
  • This genetic signature was first noted by Reifenberger et al in 1994. [3]

How is it detected?[edit | edit source]

  • Chromosome 1p/19q codeletion is demonstrated by fluorescence in situ hybridization (FISH) [4]
  • Demonstration of 1p/19q codeletion in addition to demonstration of IDH mutation, is now necessary for the diagnosis of oligodendroglioma,
  • FISH probes do not directly demonstrate complete deletion of the entire arms of chromosomes
  • Thus, alternative molecular testing methods that probe copy number changes along entire chromosomes (gene chip arrays for example) are preferred and will limit false positive results

Clinical Significance[edit | edit source]

Gliomas that have lost the entire short arm of chromosome 1 (1p) and the entire long-arm of chromosome 19 (19q), have 2 distinct prognostic features [5]:

  1. they grow slowly, even those that are anaplastic
  2. they respond to DNA damaging therapies

References[edit | edit source]

  1. Jenkins RB, Blair H, Ballman KV, et al. A t(1;19)(q10;p10) mediates the combined deletions of 1p and 19q and predicts a better prognosis of patients with oligodendroglioma. Cancer Res. 2006;66:9852–9861
  2. Griffin CA, Burger P, Morsberger L, et al. Identification of der(1; 19)(q10;p10) in five oligodendrogliomas suggests mechanism of concurrent 1p and 19q loss. J Neuropathol Exp Neurol. 2006;65:988 –994
  3. Reinfenberger J, Reinfenberger G, Liu L, et al. Molecular genetic analysis of oligodendroglial tumors shows preferential allelic deletions on 10q and 1p. Am J Pathol. 1994;145:1175–1190
  4. Ferris, Sean P.; Hofmann, Jeffrey W.; Solomon, David A.; Perry, Arie (2017). Characterization of gliomas: from morphology to molecules. Virchows Archiv, (), –. doi:10.1007/s00428-017-2181-4
  5. Cairncross, Gregory; Jenkins, Robert (2008). Gliomas With 1p/19q Codeletion:a.k.a. Oligodendroglioma. The Cancer Journal, 14(6), 352–357. doi:10.1097/ppo.0b013e31818d8178

Categories: Neurosurgery, Gliomas