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Test Code LAB20684 IDH1 (R132) and IDH2 (R140 and R172) Quantitative Detection, Droplet Digital PCR, Varies


Shipping Instructions


1. Refrigerated specimens must arrive within 14 days of collection, and ambient specimens must arrive within 7 days of collection.

2. Collect and package specimen as close to shipping time as possible.



Necessary Information


The following information is required:

1. Pertinent clinical history

2. Date of collection

3. Specimen source (blood or bone marrow)



Specimen Required


Submit only 1 of the following specimens

 

Specimen Type: Whole blood

Container/Tube:

Preferred: Lavender top (EDTA)

Acceptable: Yellow top (ACD-B) or green top (heparin)

Specimen Volume: 4mL

Collection Instructions:

1. Invert several times to mix blood.

2. Send whole blood specimen in original tube. Do not aliquot.

3. Label specimen as blood.

Specimen Stability: Refrigerated 14 days/ Ambient 7 days

 

Specimen Type: Bone marrow aspirate

Container/Tube:

Preferred: Lavender top (EDTA)

Acceptable: Yellow top (ACD-B) or green top (heparin)

Specimen Volume: 2mL

Collection Instructions:

1. Invert several times to mix bone marrow.

2. Send bone marrow specimen in original tube. Do not aliquot.

3. Label specimen as bone marrow.

Specimen Stability: Refrigerated 14 days/ Ambient 7 days

 

Specimen Type: Extracted DNA from blood or bone marrow

Container/Tube: 1.5- to 2-mL tube with indication of volume and concentration of DNA

Specimen Volume: Entire specimen

Collection Instructions:

1. Label specimen as extracted DNA and source of specimen

2. Indicate volume and concentration of DNA on label. The required volume of DNA is at least 50 mcL at a concentration of 50 ng/mcL

Specimen Stability: Frozen (preferred)/Refrigerated


Forms

1. Hematopathology Patient Information (T676)

2. If not ordering electronically, complete, print, and send an Hematopathology/Cytogenetics Test Request (T726) with the specimen.

Secondary ID

615859

Useful For

Detecting IDH1 R132 and IDH2 R140 and R172 mutations in acute myeloid leukemia patients at the time of diagnosis to guide targeted therapy

 

Monitoring minimal residual disease during the clinical and therapeutic course

Method Name

Droplet Digital Polymerase Chain Reaction (ddPCR)

Reporting Name

IDH1 and IDH2, Quant, ddPCR, V

Specimen Type

Varies

Specimen Minimum Volume

Whole blood: 4mL
Bone marrow: 2mL
Extracted DNA: 50 mcL at 50 ng/mcL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Varies Refrigerated (preferred) 14 days
  Ambient  7 days

Reject Due To

Gross hemolysis Reject
Moderately to severely clotted Reject

Clinical Information

Isocitrate dehydrogenase 1 (IDH1) is a cytosolic/peroxisomal enzyme involved in citric acid cycle and other cellular metabolic processes. It catalyzes the oxidative decarboxylation of isocitrate to alpha-ketoglutarate (a-KG), generating reduced nicotinamide adenine dinucleotide phosphate (NADPH) from NADP(+). Isocitrate dehydrogenase 2 (IDH2) is a mitochondrial NADP(+)-dependent enzyme that catalyzes the oxidative decarboxylation of isocitrate to a- KG, generating NADPH from NADP(+). Mutations in codon R132 of IDH1 or R140 or R172 in IDH2 confer an abnormal enzyme activity that converts a-KG to D-2- hydroxyglutarate (2-HG) resulting in elevation of 2-HG and a hypermethylation state, associated in myeloid neoplasms including acute myeloid leukemia (AML). IDH1 and IDH2 point mutations are seen in approximately 5% to 33% de novo acute myeloid leukemia (AML) and 7% to 25% secondary AML.

 

The US Food and Drug Administration (FDA) has approved ivosidenib (AG-120) for the treatment of newly-diagnosed IDH1-mutated AML (patients 75 years of age and older or who have comorbidities that preclude the use of intensive induction chemotherapy) and relapsed/refractory AML in adult patients.(1) The FDA has also approved enasidenib (AG-221) for the treatment of IDH2-mutated relapsed/refractory AML.(2)

 

IDH1 and IDH2 have also been shown to be suitable minimal residual disease markers for AML post-therapy.

Reference Values

An interpretive report will be provided.

Interpretation

The assay is reported as positive or negative. In positive cases, the mutation and its variant allele fraction (VAF) are reported.

 

VAF%= (mutant copy number)/(mutant copy number + wild-type number)

 

The precision of this quantitative assay is excellent but interassay variability may occur such that result changes should not be considered significant if 2 single measurements differ by less than 0.5 log (3.16-folds).

Method Description

This test will be performed on Bio-Rad QX200 digital polymerase chain reaction (PCR) system. Mutation-specific droplet digital PCR probes were designed using Thermo Fisher Scientific MGB (minorgroove binder) Taqman technology. The PCR reactions for each patient are placed into an 8-tube cartridge along with droplet generation oil. The cartridge is loaded onto the droplet generator instrument to partition each reaction into 20,000 nanoliter-sized droplets.

 

Droplets are transferred to a plate for PCR amplification. Targets are amplified by end-point PCR in each droplet. The QX200 automated droplet reader counts every acceptable droplet and measures fluorescence emissions from each droplet using two different fluorescence channels (FAM and VIC). QuantaSoft software measures the number of negative and positive droplets for each fluorophore in each sample. Poisson statistics are used to determine the concentration of mutant and wild type copies in the sample.(Unpublished Mayo method)

Day(s) Performed

Monday through Saturday

Report Available

4 to 8 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Test Classification

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

CPT Code Information

81120

81121

LOINC Code Information

Test ID Test Order Name Order LOINC Value
IDHQ IDH1 and IDH2, Quant, ddPCR, V 95772-0

 

Result ID Test Result Name Result LOINC Value
MP063 Specimen Type 31208-2
618389 Interpretation 69047-9
618390 Signing Pathologist 18771-6