Days Set Up
Monday - Thursday
Analytic Time

5-12 days

MiChart Code
IDHG
Soft Order Code
IDHG

Test Updated:

Synonyms
 

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Test Overview

Test Methodology

Next-Generation Sequencing

Test Usage

This test is intended to detect IDH1 or IDH2 mutations within glioma or suspected glioma specimens.

IDH1 and IDH2 encode the cytoplasmic and mitochondrial isocitrate dehydrogenase enzymes that normally convert isocitrate into alpha-ketoglutarate. Mutations affecting arginine residues in these proteins result in the production of 2-hydroxyglutarate which functions as an oncometabolite. 2-hydroxyglutarate inhibits alpha-ketoglutarate dependent dioxygenases such as TET enzymes, leading to global DNA and histone methylation changes.
Mutation status for IDH1 and IDH2 determines the final classification of diffuse astrocytic and oligodendroglial tumors according to the World Health Organization Classification of Tumors of the Central Nervous System. IDH mutations in glioma (most frequently IDH1 R132H) impart a significantly better prognosis than grade-matched IDH wild-type gliomas and these mutations are associated with superior response to chemotherapy. These mutations can be associated with 1p/19q co-deletion and/or MGMT promoter methylation.

Reference Range

Interpretive report provided.

* Reference ranges may change over time. Please refer to the original patient report when evaluating results.

Specimen Requirements

Collection Onsite

For formalin-fixed, paraffin-embedded tissue, a block containing an area with a high percentage of neoplastic cells (for micro-/macro-dissection) is preferred. Unstained, UNBAKED slides (5-8, 10-micron slides; 10-15 if few neoplastic cells are present) with associated H&E stained slide are also acceptable. Decalcified tissue or other fixatives will be accepted and the assay attempted, however these may result in failed testing due to degraded nucleic acid. Both blocks and slides should be stored at room temperature. A Diff-Quik or Papanicolaou stained aspirate smear (preferable containing a high percentage and overall amount of neoplastic cells) is also acceptable. Store at room temperature.

Collection Offsite

For formalin-fixed, paraffin-embedded tissue, a block containing an area with a high percentage of neoplastic cells (for micro-/macro-dissection) is preferred. Unstained, UNBAKED slides (5-8, 10-micron slides; 10-15 if few neoplastic cells are present) with associated H&E stained slide are also acceptable. Decalcified tissue or other fixatives will be accepted and the assay attempted, however these may result in failed testing due to degraded nucleic acid. Both blocks and slides should be stored at room temperature. A Diff-Quik or Papanicolaou stained aspirate smear (preferable containing a high percentage and overall amount of neoplastic cells) is also acceptable. Store at room temperature.

Normal Volume
Formalin-fixed, paraffin-embedded tissue; Diff-Quik stained aspirate smear, Papanicolaou stained aspirate smear.
Minimum Volume
 

Billing Information

CPT Code
81120, 81121, 88381-TC
Pro Fee Code
 
LOINC
 

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Our High Standard

Quality that sets us apart

As the reference laboratory division of Michigan Medicine's Department of Pathology, MLabs shares the institution's commitment to applying established quality principles to clinical laboratory testing. Like other large organizations in complex, consequential fields, we rely on an established approach to monitor quality throughout the testing process.