Test Catalog

Test ID: GLIOF    
1p/19q Deletion in Gliomas, FISH, Tissue

Useful For Suggests clinical disorders or settings where the test may be helpful

Aids in diagnosing oligodendroglioma tumors and predicting the response of an oligodendroglioma to therapy


May be useful in tumors with a complex "hybrid" morphology requiring differentiation from pure astrocytomas to support the presence of oligodendroglial differentiation/lineage


Indicated when a diagnosis of oligodendroglioma, both low-grade World Health Organization (WHO, grade II) and anaplastic (WHO, grade III) is rendered


Strongly recommended when a diagnosis of mixed oligoastrocytomas is rendered

Testing Algorithm Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

This test does not include a pathology consult. If a pathology consultation is requested, PATHC / Pathology Consultation should be ordered and the appropriate FISH test will be ordered and performed at an additional charge.


This test includes a charge for application of the first probe set (2 FISH probes) and professional interpretation of results. Additional charges will be incurred for all reflex probes performed. Analysis charges will be incurred based on the number of cells analyzed per probe set. If no cells are available for analysis, no analysis charges will be incurred.


Chromosomal microarray (CMAPT / Chromosomal Microarray, Tumor, Formalin-Fixed Paraffin-Embedded), rather than FISH, may be of benefit to evaluate for acquired alterations associated with the molecular classification of glioma.(1) See Cytogenetic Analysis of Glioma in Special Instructions.

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Astrocytomas, oligodendrogliomas, and mixed oligoastrocytomas are the major histologic types of human gliomas; histologic differentiation among these tumors can be difficult. It has been shown that specific genetic alterations are highly associated with specific morphologic types of gliomas. In addition, specific genetic alterations seem to predict prognosis (survival), as well as response to specific chemotherapeutic and radiotherapeutic regimens, irrespective of tumor morphology.


Deletions of the short arm of chromosome 1(1p) and long arm of chromosome 19 (19q), are strongly correlated with gliomas of oligodendroglial morphology. Approximately 70%, 50%, and 50% of oligodendrogliomas have deletions of 19q, 1p, and of both 19q and 1p, respectively.


Combined 1p and 19q loss is infrequent in gliomas of astrocytic origin. Thus, the presence of combined 1p/19q loss is strongly suggestive that a glioma is of oligodendroglioma lineage.


Gains of chromosome 19 and of the 19 q-arm are associated with gliomas of astrocytic origin.


Deletions of 1p and of both 1p and 19q also have been associated with response to various chemotherapeutic and radiotherapeutic regimens. These responses have been especially associated with high-grade oligodendrogliomas (anaplastic oligodendrogliomas).


Chromosomal microarray (CMAPT / Chromosomal Microarray, Tumor, Formalin-Fixed Paraffin-Embedded), rather than FISH, may be of benefit to evaluate for acquired alterations associated with the molecular classification of glioma.(1) See Cytogenetic Analysis of Glioma in Special Instructions.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

An interpretive report will be provided.

Interpretation Provides information to assist in interpretation of the test results

The presence of 1p deletion and combined 1p and 19q deletion supports a diagnosis of oligodendroglioma may indicate that the patient may respond to chemotherapy and radiation therapy.


The presence of gain of chromosome 19 supports a diagnosis of high-grade astrocytoma (glioblastoma multiforme).


A negative result does not exclude a diagnosis of oligodendroglioma or high-grade astrocytoma.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

This test is not approved by the US FDA, and it is best used as an adjunct to existing clinical and pathologic information.

Supportive Data

See Incidence of 1p and 19q Losses Versus Glioma Subtype and Primary Status in Special Instructions. The table summarizes the incidence of 1p deletion, 19q deletion, and combined 1p and 19q deletion in a series of tumors from Mayo Clinic and Johns Hopkins University. The laboratory also has detected a similar incidence of 1p and 19q deletions in a series of 189 high-grade oligodendrogliomas from patients enrolled in a Radiation Therapy Oncology Group (RTOG) trial.

Clinical Reference Recommendations for in-depth reading of a clinical nature

1. Eckel-Passow JE, Lachance DH, Molinaro AM, et al: Glioma Groups Based on 1p/19q, IDH, and TERT Promoter Mutations in Tumors. N Engl J Med 2015 Jun 25;372(26):2499-2508

2. James CD, Smith JS, Jenkins RB: Genetic and molecular basis of primary central nervous system tumors. In Cancer in the Nervous System. Edited by VA Levine. New York, Oxford University Press, 2002, pp 239-251

3. Cairncross JG, Ueki K, Zlatescu MC, et al: Specific genetic predictors of chemotherapeutic response and survival in patients with anaplastic oligodendrogliomas. J Natl Cancer Inst 1998 October 7;90(19):1473-1479

4. Ino Y, Zlatescu MC, Sasaki H, et al: Long survival and therapeutic responses in patients with histologically disparate high-grade gliomas demonstrating chromosome 1p loss. J Neurosurg 2000 June;92(6):983-990

5. Smith JS, Tachibana I, Passe SM, et al: PTEN mutation, EGFR amplification, and outcome in patients with anaplastic astrocytoma and glioblastoma multiforme. J Natl Cancer Inst 2001 August 15;93(16):1246-1256

6. Smith JS, Alderete B, Minn Y, et al: Localization of common deletion regions on 1p and 19q in human gliomas and their association with histological subtype. Oncogene 1999 July 15;18(28):4144-4152

7. Smith JS, Perry A, Borell TJ, et al: Alterations of chromosome arms 1p and 19q as predictors of survival in oligodendrogliomas, astrocytomas, and mixed oligoastrocytomas. J Clin Oncol 2000 February;18(3):636-645

8. Jenkins RB, Curran W, Scott CB, et al: Pilot evaluation of 1p and 19q deletions in anaplastic oligodendrogliomas collected by a national cooperative cancer treatment group. Am J Clin Oncol 2001 October;24(5):506-508

9. Burger PC: What is an oligodendroglioma? Brain Pathol 2002;12:257-259

Special Instructions Library of PDFs including pertinent information and forms related to the test