Test Catalog

Test ID: MEDF    
Medulloblastoma, FISH, Tissue

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

Identifying MYCN amplification, MYC amplification, and monosomy of chromosome 6 (detected using MYB probe), to aid in the classification of medulloblastoma patients into specific clinical categories

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

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

Medulloblastoma is the most common malignant brain tumor in children. Current treatment decisions are based on clinical variables. Biomarkers have been identified that allow classification of medulloblastoma into subtypes that are associated with a specific clinical behavior. FISH analyses for the MYCN, MYB, and MYC loci may be useful in medulloblastoma patients to help provide prognostic information and guide treatment.

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 MYCN locus is reported as amplified when the MYCN:D2Z1 ratio is 2.0 or greater and demonstrates 8 or more copies of the MYCN locus.

-A tumor with a MYCN:D2Z1 ratio <2.0 or demonstrating a ratio of 2.0 or greater with <8 copies of MYCN, is considered to lack amplification of the MYCN locus.



Monosomy of chromosome 6 is reported when the percent of cells with the abnormality exceeds the normal cutoff for the probe set.



-The MYC locus is reported as amplified when the MYC:D8Z2 ratio is 2.0 or greater and demonstrates 8 or more copies of the MYC locus.

-A tumor with a MYC:D8Z2 ratio <2.0 or demonstrating a ratio of 2.0 or greater with <8 copies of MYC, is considered to lack amplification of the MYC locus.

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 Food and Drug Administration and is best used as an adjunct to existing clinical and pathologic information.


Fixatives other than formalin (eg, Prefer, Bouin) may not be successful for FISH assays, however nonformalin-fixed samples will not be rejected.


Paraffin-embedded tissues that have been decalcified are generally unsuccessful for FISH analysis. The pathologist reviewing the hematoxylin and eosin-stained slide may find it necessary to cancel testing.

Supportive Data

FISH analysis was performed on 15 formalin-fixed, paraffin-embedded samples from patients diagnosed with medulloblastoma. For each probe set, a series of normal control samples were used to generate the normal cutoffs. MYCN amplification was detected in 1 (7%) of the samples, monosomy 6 was detected in 2 (13%) samples, and MYC amplification was detected in 1 (7%) of the samples, which correlated with pathology review.

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

1. Ellison DW, Kocak M, Dalton J, et al: Definition of disease-risk stratification groups in childhood medulloblastoma using combined clinical, pathologic, and molecular variables. J Clin Oncol 2011;29:1400-1407

2. Pfister S, Remke M, Benner A, et al: Outcome prediction in pediatric medulloblastoma based on DNA copy-number aberrations of chromosomes 6q and 17q and the MYC and MYCN loci. J Clin Oncol 2009;27:1627-1636

3. Ryan S, Schwalbe E, Cole M, et al: MYC family amplification and clinical risk-factors interact to predict an extremely poor prognosis in childhood medulloblastoma. Acta Neuropathol 2012 Apr;123(4):501-513

4. Tomlinson FH, Jenkins RB, Scheithauer BW, et al: Aggressive medulloblastoma with high-level N-myc amplification. Mayo Clin Proc 1994;69:359-365