IDH1/IDH2 Mutation Analysis [IDHM]
|IDH1/IDH2 Mutation Analysis [IDHM]|
| WSLH Department:|| Cytogenetics|
|WSLH Test Code:||840C55|
|Includes:||FFPE tissue sections of tumors and representative blood/cell/bone marrow specimens are selected and reviewed by a pathologist or a hematopathologist, respectively. Relevant FFPE tumor tissue is macro-dissected for mutational analysis. Following de-paraffinization of the tissue and receipt of specimens, genomic DNA is isolated by automated nucleic acid extraction. Polymerase chain reaction (PCR) is used to amplify across regions of theIDH1 (codon 132) and IDH2 (codons 140 and 172) genes. Following PCR, detection of mutations in codon 132 of IDH1and codons 140 and 172 of IDH2 is accomplished through a series of primer extension reactions in which the resultant products are analyzed using a MassARRAY System with Chip prep module (Agena Bioscience; San Diego, CA USA)
*Approximately 90% of all IDH mutations occur in codon 132, exon 4 of the IDH1 gene, and less frequently, in codons 140 and 172, exon 4 of the IDH2 gene. Consequently, this test was validated to qualitatively detect mutations in codon 132 of IDH1 (R132H, R132C, R132S, R132G, R132H and R132V) and mutations in both codon 140 (R140Q and R140L) and 172 (R172M and R172K) in IDH2 in DNA extracted from formalin-fixed, paraffin embedded (FFPE) tissue, fresh/frozen tissue, peripheral blood and bone marrow specimens. The analytical sensitivity of the assay has been established to be ~10%. Consequently, IDH1 (codon 132) and IDH2 (codons 140 and 172) mutations present in cells at<10% may not be detected. Detection of IDH1 (codon 132) and IDH2 (codons 140 and 172) mutations depend on numerous factors including, but not limited to, the integrity and heterogenous nature of tissue/tumor samples, the presence/absence of PCR inhibitors and/or the presence/absence of other proximal mutations and/or DNA sequence polymorphisms in IDH1 and IDH2. Test results should not be used as the only criterion to form a clinical conclusion, but should be interpreted in the context of all clinical findings, tumor sampling and lab data.|
|Methodology:||**(CPT Codes: 81403x2)** MassARRAY (Mass Spectrometry)|
|Availability:||Batched runs begin Monday/first working day and Wednesday of each week|
|Turn-around Time:||10 Days|
|Recommended Uses:||Isocitrate dehydrogenase enzyme isoforms 1 (IDH1) and 2 (IDH2) are nicotinamide adenine dinucleotide phosphate (NADP)-dependent isocitrate dehydrogenases that catalyze the oxidative decarboxylation of isocitrate to produce alpha-ketoglutarate in normal cell metabolism. Mutation in IDH1 or IDH2 is mutually exclusive and appears to be an early event in the development of certain tumors that impairs normal enzyme activity, resulting in loss of the ability to catalyse conversion of isocitrate to alpha-ketoglutarate. However, as a result, the mutated isoforms now acquire a neomorphic activity able to catalyze the NADPH-reduction of alpha-ketoglutarate to R(-)-2-hydroxyglutarate (2HG), a presumed oncometabolite. While no therapies directly targeting IDH1 or IDH2 mutated proteins are currently approved, cells that accumulate 2HG may have altered epigenetic regulation due to hypermethylation and as a result be sensitive to DNA methyltransferase inhibitors. The presence of an IDH1 or IDH2 mutation has both diagnostic and prognostic significance in central nervous system (CNS) tumors and prognostic value in hematologic disorders, such as MDS and AML.
*Mutations in IDH1 and, to a lesser extent(5-10% of all IDH mutation), isoform 2 (IDH2) genes have been identified in a large proportion of diffuse astrocytomas, oligodendrogliomas, oligoastrocytomas, and secondary glioblastomas. Additionally, these mutations have been found to be associated with a younger age (<55 years old) among cases of adult diffuse astrocytomas, WHO grade III astrocytomas, and glioblastomas. Similar to CNS tumors, mutation in IDH1 or IDH2 serves as a prognostic factor in certain hematopoetic malignancies. However, in contrast to CNS tumors, IDH1 and IDH2 mutations have generally been associated with more unfavorable outcomes and shorter overall survival, particularly in cases of MDS and AML with a normal cytogenetic karyotype that lack FLT3 or NPM1 mutations.|
|Specimen Requirements:||*Stability Ambient: Indefinitely
*Stability Refrigerated: Indefinitely
*Stability Frozen: Not acceptable|
|Collection Kit/Container:|| |
|Patient Preparation:|| |
|Collection Instructions:||Formalin-fixed, paraffin embedded tissue, whole blood or bone marrow aspirate. Lavender Top Tube for Blood or Bone Marrow specimens. 1.0 mL required.|
|Specimen Handling and Transport:||Transport at room temperature. Outreach: Transport with a cold pack. Avoid excessive heat.|
|Unacceptable Conditions:||Blood/Bone Marrow Aspirate - Whole Blood. Do not centrifuge or freeze.|
|Requisition Form:||Cytogenetics Lab Neoplasia Diagnosis Form #132|
|Required Information:|| |
|Results include:||A written interpretive report is provided by the laboratory.
This method is qualitative.
Codons assessed: IDH1 (R132), IDH2 (R140 and R172)
*Not Detected - variant in specified codon was not detected.
*Detected - variant in specified codon was detected.|
|Limitations:||The lower limit of detection for tumor DNA in a normal DNA background is approximately 5-10%.|
|Additional Tests Recommended:|| |
|Additional Comments:||Inadequate specimen collection, processing and storage may invalidate test results. This test should not be used as the only criterion to form a clinical conclusion, instead, results should be correlated with other test results, patient symptoms and clinical presentation.
The performance characteristics of this test were validated by UWHC Clinical Laboratories. The U.S. Food and Drug Administration (FDA) has not approved or cleared this test; however, FDA approval or clearance is currently not required for clinical use of this test. The results are not intended to be used as the sole means for clinical diagnosis or patient management decisions. The UWHC Clinical Laboratories is authorized under Clinical Laboratory Improvement Amendments (CLIA) to perform high-complexity testing.|
|Additional Tests Performed:|| |
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