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Test Code IDH IDH1/2, Mutation Analysis

Useful For

Supporting a morphological diagnosis of a diffuse glioma

 

Assisting in central nervous system tumor classification

 

Stratifying prognosis of diffuse gliomas

 

Assessing for the following mutations: IDH1 mutations R132H, R132C, R132G, R132L, R132S, R132P; and IDH2 R172K, R172G, R172M

Additional Tests

Test ID Reporting Name Available Separately Always Performed
SLIRV Slide Review in MG No, (Bill Only) Yes

Testing Algorithm

This test is performed in conjunction with SLIRV / Slide Review. Additional testing may be performed after review by pathologist. Upon approval from the requesting clinician, PATHC / Pathology Consultation may be added, if determined to be appropriate.

Special Instructions

Method Name

Polymerase Chain Reaction (PCR) and Pyrosequencing

Reporting Name

IDH1/2, Mutation Analysis

Specimen Type

Varies


Necessary Information


A pathology/diagnostic report including a brief history is required.

If available, include IDH1 mutation (R132H) immunostain results.



Specimen Required


Supplies: Pathology Packaging Kit (T554)

Specimen Type:

Container/Tube: Surgical Pathology Packaging Kit (T554) requested, but not required

Preferred: Formalin-fixed, paraffin-embedded (FFPE) tissue block with a minimum of 40% tumor cell population

Alternate: Unstained slides with a minimum of 40% tumor population; slides may be stained and/or scraped

Collection Instructions:

1. Process all fresh or frozen specimens into FFPE blocks prior to submission.

2. If submitting slides, a minimum of five, 4- to 5-micron thick, unstained slides are required.

Additional Information:

1. A quality specimen is essential for evaluation. Submit only tissue containing tumor cells; minimal tissue is required for evaluation.

2. Special stains performed outside Mayo Medical Laboratories and included with the case may be repeated and charged at the reviewing pathologist's discretion. Testing requested by referring physician may not be performed if deemed unnecessary by Mayo Clinic pathologist.


Specimen Stability Information

Specimen Type Temperature Time
Varies Ambient (preferred)
  Frozen 
  Refrigerated 

Reject Due To

Hemolysis

NA

Lipemia

NA

Icterus

NA

Other

Specimens that have been decalcified (all methods, including EDTA); specimens that have not been formalin-fixed, paraffin-embedded; bone marrow in EDTA.

Clinical Information

IDH1 and IDH2 genes encode dehydrogenase enzymes that are involved in cellular glucose metabolism and oxidative damage control. IDH mutations, primarily involving codons R132 in IDH1 and R172 in IDH2, result in reduction of the enzyme physiological activity and gain of a neomorphic ability to generate oncometabolite R(-)-2-hydroxyglutarate. This contributes to tumorigenesis by altering numerous cellular responses, including genome-wide epigenetic changes that characterize the glioma CpG island methylator phenotype (G-CIMP). IDH mutations seem to be an early event in gliomagenesis and have been identified in over 70% of lower-grade (grades II/III) diffuse gliomas and secondary glioblastoma. These mutations are rarely seen in other central nervous system tumors and not seen in reactive non-neoplastic processes, and define a group of lower and high-grade diffuse gliomas associated with a more favorable prognosis. Assessment of IDH mutation status in central nervous system tumors may assist in tumor classification and provide prognostically relevant information for subgroups of patients with diffuse gliomas.

Reference Values

An interpretative report will be provided.

Interpretation

The presence of an IDH1 or IDH2 mutation supports a diagnosis of grade II or III astrocytoma, oligodendroglioma, oligoastrocytoma, or secondary glioblastoma (GBM) in the context of other corroborating pathologic features.

 

IDH1 codon 132 and IDH2 codon 172 mutations have been identified in more than 70% of brain tumors diagnosed as grade II and III astrocytoma, oligodendroglioma, oligoastrocytoma, and secondary GBM. These mutations are rarely found in other brain tumors and nonbrain tumors. The ordering physician is responsible for the diagnosis and management of disease and decisions based on the data provided.

 

A negative result does not exclude the presence of a brain tumor.

Cautions

Mutations at codons other than those listed (see Useful For), including IDH2 R140, are not analyzed by this test.

 

Reliable results are dependent on adequate specimen collection and processing. This test has been validated on formalin-fixed, paraffin-embedded tissues; other types of fixatives are discouraged. Improper treatment of tissues, such as decalcification, may cause PCR failure. False-negative results may occur in heterozygous tumor specimens when tumor cells comprise <40% of the cell population. Tumor cells are routinely enriched by macrodissection to avoid false-negative results.

 

Clinical diagnosis and therapy should not be based solely on this assay. The results should be considered in conjunction with clinical information, histologic evaluation, and additional diagnostic tests.

 

This test is designed to detect mutations in codon 132 of the IDH1 gene and codon 172 of the IDH2 gene and does not detect mutations in other areas of these genes.

Supportive Data

In a validation study performed in our laboratory, 61 tumor specimens and 6 normal brain tissue specimens were assessed for IDH1 and IDH2 mutations. The tumor specimens included 18 low-grade oligoastrocytoma or oligodendroglioma, 19 high-grade oligoastrocytoma or oligodendroglioma, 6 low-grade astrocytoma, 8 pilocytic astrocytoma, 5 glioblastoma multiforma/grade IV oligoastrocytoma, and the glioma tumor type was unavailable for 5.

 

One specimen could not be analyzed by pyrosequencing for IDH1 mutations due to an inadequate amount of PCR product. Of the remaining 66 specimens, 29 were wild-type, and 37 had mutations of codon 132 the IDH1 gene. Of the 37 specimens showing mutations, 34 had the most common Arg132His (CGT->CAT) mutation, 2 had an Arg132Gly (CGT->GGT) mutation, and 1 had an Arg132Ser (CGT->AGT) mutation. All results were confirmed by Sanger sequencing resulting in 100% concordance between the 2 methods.

 

When evaluating the same specimens for IDH2 gene mutations, pyrosequencing detected an Arg172Lys (AGG->AAG) mutation in 3 specimens with all other specimens lacking an IDH2 mutation. Sanger sequencing detected 2 of 3 mutations identified by pyrosequencing, and confirmed the wild-type sequence in all other specimens, which resulted in a concordance of 98% between the 2 methods.

Clinical Reference

1. Parsons DW, Jones S, Zhang X, et al: An integrated genomic analysis of human glioblastoma multiforme. Science. 2008 Sep 26;321(5897):1807-1812

2. Yan H, Parsons DW, Jin G, et al: IDH1 and IDH2 mutations in gliomas. N Engl J Med. 2009 Feb 19;360(8):765-773

3. Hartmann C, Meyer J, Balss J, et al: Type and frequency of IDH1 and IDH2 mutations are related to astrocytic and oligodendroglial differentiation and age: a study of 1,010 diffuse gliomas. Acta Neuropathol. 2009 Oct;118(4):469-474

4. Cancer Genome Atlas Research Network, Brat DJ, Verhaak RG, et al: Comprehensive, Integrative Genomic Analysis of Diffuse Lower-Grade Gliomas. N Engl J Med. 2015 Jun 25;372(26):2481-2498

5. 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

Method Description

Paraffin-embedded tissue is deparaffinized, lysed, and digested. Genomic DNA is then extracted from the sample using either a phenol-chloroform method or the QIAamp DNA FFPE Tissue kit (Qiagen). The DNA is PCR amplified using primers specific for regions surrounding IDH1 codon 132 (R132H, R132C, R132G, R132L, R132S, R132P) and IDH2 codon 172 (R172K, R172G, R172M). Controls are run with each specimen to assess possible contamination issues and overall test performance. Samples are pyrosequenced and pyrograms are analyzed for the presence or absence of IDH1 codon 132 and IDH2 codon 172 mutations.(Qiagen DNA FFPE Tissue Handbook, Qiagen PyroMark Gold Q24 reagents Handbook; Unpublished Mayo method)

Day(s) and Time(s) Performed

Monday through Friday; Varies

Analytic Time

8 days

Specimen Retention Time

Unused portions of blocks will be returned. Slides are stored indefinitely.

Performing Laboratory

Mayo Medical Laboratories in Rochester

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

CPT Code Information

81120-IDH1 (isocitrate dehydrogenase 1 [NADP+], soluble) (eg, glioma), common exon 4 variants (eg, R132H, R132C)

81121-IDH2 (isocitrate dehydrogenase 2 [NADP+], mitochondrial) (eg, glioma), common exon 4 variants (eg, R140W, R172M)

88381-Microdissection, manual

LOINC Code Information

Test ID Test Order Name Order LOINC Value
IDH IDH1/2, Mutation Analysis In Process

 

Result ID Test Result Name Result LOINC Value
52948 Result Summary 50397-9
52949 Result In Process
52950 Interpretation 50595-8
52951 Additional Information 48767-8
52952 Reason for Referral 42349-1
52953 Specimen 31208-2
52954 Source 31208-2
52955 Tissue ID No LOINC Needed
52956 Released By No LOINC Needed

Forms

1. Pathology/Cytology Information (T707) in Special Instructions

2. If not ordering electronically, complete, print, and send 1 of the following forms with the specimen:

Pathology Test Request Form (T246) (http://www.mayomedicallaboratories.com/it-mmfiles/pathology-request-form.pdf)

Oncology Test Request Form (T729) (http://www.mayomedicallaboratories.com/it-mmfiles/oncology-request-form.pdf)

Genetics Test Information

This test assess for the following mutations: IDH1 R132H, R132C, R132G, R132L, R132S, R132P; and IDH2 R172K, R172G, R172M. Other mutations at these codons and mutations at other codons are not assessed by this assay.

 

This test is not recommended for evaluation of acute myeloid leukemia (AML) due to insufficient coverage of codons 140 and 172 of IDH2 associated with AML.

 

If considering IDH testing for the evaluation of acute myeloid leukemia (AML) using a bone marrow specimen (in EDTA), order NGAML / Next-Generation Sequencing (NGS), Acute Myeloid Leukemia, 8-Gene Panel.

 

If considering IDH testing for the evaluation of AML using a formalin-fixed, paraffin-embedded specimen, order CAPN / Solid Tumor Targeted Cancer Gene Panel by Next-Generation Sequencing.