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    v1.0.30
    OpenPayerBilling CodesGenetic Analysis ProceduresCPT cpt-81121-idh2-molecular-diagnostic-test
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    CPT 81121: IDH2 Mutation Detection, Technical Component

    CPT code 81121 describes a molecular laboratory test where a lab analyst performs the technical component to detect common mutations in the mitochondrial gene encoding isocitrate dehydrogenase 2 (IDH2); this is a molecular pathology / genetic sequencing service performed in a clinical molecular diagnostics laboratory or similar outpatient laboratory setting.

    For related coverage guidance, see recent payer policy updates: Oral Cancer Screening and Testing, RTM Testing for Alpha-1 Antitrypsin Deficiency, Cytochrome P450 Genotype-Guided Treatment Strategy Corporate Medical Policy.

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    Clinical & Coding Specifications

    Clinical Context

    A patient with newly diagnosed or suspected myeloid malignancy (for example acute myeloid leukemia or myelodysplastic syndromes) is referred for molecular testing to evaluate for somatic variants in the mitochondrial isocitrate dehydrogenase 2 gene (IDH2). A typical scenario is a hematology-oncology clinic visit where the oncologist orders targeted molecular testing on a peripheral blood or bone marrow specimen to identify IDH2 hotspot mutations that impact prognosis and targeted therapy selection. The clinical workflow includes: specimen collection (blood or bone marrow), accessioning in the molecular pathology laboratory, DNA extraction, performance of the analytical assay (e.g., PCR-based allele-specific testing or next-generation sequencing panel targeting IDH2), result verification by the lab analyst and molecular pathologist, incorporation of results into the pathology report, and communication to the ordering hematologist-oncologist for treatment planning. The usual site of service is an outpatient clinic or hospital laboratory associated with a cancer center; the technical performance of the test occurs in a certified clinical molecular diagnostics laboratory.

    Related CPT Codes

    CPT CodeDescriptionRelationship to This Procedure
    81025Urinalysis, by dipstick or tablet reagent; non-automated, with microscopyData not relevant to molecular IDH2 testing; included only if urine is used for ancillary testing
    81320Molecular cytogenetics; somatic mutation analysis, IDH1 (isocitrate dehydrogenase 1), common variantsOften ordered in parallel with IDH2 testing to assess complementary mutation status in myeloid neoplasms
    81445Oncology (targeted) gene sequencing panel, e.g., somatic mutation detection by NGS, per specimenIDH2 testing is frequently part of broader targeted NGS panels billed with panel codes when multiple genes are analyzed
    88360Morphometric analysis, immunohistochemistry quantificationMay be performed on bone marrow biopsies as ancillary tests in hematologic malignancy workup
    36415Collection of venous blood by venipuncturePre-analytic specimen collection commonly billed when peripheral blood is submitted for molecular testing

    Related Modifiers

    7 rows

    ModifierDescriptionWhen to Use
    26Modifier 26 (Professional Component) identifies and bills only the professional portion of a split service — the physician’s interpretation, report, and medical judgment — when the technical…- Use CPT Modifier -26 when you are billing only the professional component (PC) of a split‑bill eligible service—i.e., you performed the physician interpretation, medical judgment and prepared a…
    59Modifier 59 indicates a distinct procedural service when two procedures that are not normally billed together are clinically and procedurally separate. The CPT definition (as reiterated by CMS)…- Use modifier -59 to report a distinct procedural service when documentation supports that the procedure reported is not normally billed together with another service on the same day because of a…
    62Modifier 62 indicates that two surgeons function as co‑surgeons, each performing distinct parts of the same primary surgical procedure. It is appended to the primary procedure code (and any…- Use modifier -62 when two surgeons act as co‑surgeons (both primary surgeons) on a single definitive primary procedure, each performing distinct parts of the same surgical procedure (append -62 to…
    78CPT modifier -78 indicates an unplanned, related return to the operating or procedure room by the same provider during the global postoperative period. It is appended when treatment for a…- Use modifier -78 when an unplanned, related complication during the original procedure’s global postoperative period requires the patient to return to a formal operating or procedure room and the…
    80CPT® Modifier 80 (Assistant Surgeon) is appended to a surgical CPT code when a physician (MD or DO) provides full, continuous assistance throughout the operative procedure. It is intended only for…- Use CPT Modifier -80 when a physician (MD or DO) serves as an assistant surgeon and provides full, continuous assistance throughout the entire operative procedure; append -80 to the surgical CPT…
    90Modifier ‑90 (Reference/Outside Laboratory) indicates that a laboratory test was performed by an entity other than the treating or reporting provider. The American Medical Association defines…- Use CPT modifier -90 when a laboratory test is performed by an outside/reference laboratory (an entity other than the treating or reporting physician or qualified professional) and the claim needs…
    52Modifier ‑52 (Reduced Services) indicates that a service or procedure was partially reduced or omitted at the provider’s discretion, allowing reporting of the basic procedure number with a qualifier…- Use modifier -52 when a physician or qualified health professional electively reduces or omits part of a procedure or service (for example, performing fewer required views or omitting a portion of…

    Related Provider Taxonomies

    8 rows

    Taxonomy Code
    207RH0000X
    207L00000X
    364SR0400X
    207PP0204X
    103G00000X
    133N00000X
    335G00000X
    207RX0202X

    Related Payer Policy Updates

    Specialty: Genetic & Molecular Testing1 / 3

    10 rows

    PolicyPayerEffective Date
    Oral Cancer Screening and TestingOscar Health2027-01-01
    RTM Testing for Alpha-1 Antitrypsin DeficiencyOscar Health2027-01-01
    Cytochrome P450 Genotype-Guided Treatment Strategy Corporate Medical Policybcbsvermont2027-01-01
    Carrier Testing Panels for Genetic Diseases (for Kentucky Only)UnitedHealthcare2026-10-01
    Genetic Testing for Neurological Disorders (for Kansas Only)UnitedHealthcare2026-10-01
    Genetic and Molecular TestingProvidence Health Plan2026-10-01
    Cell-Free Fetal DNA Testing (for Idaho Only)UnitedHealthcare2026-10-01
    Next Generation Sequencing for Minimal Residual Disease DetectionProvidence Health Plan2026-10-01
    Pharmacogenetic Panel Testing (for Kansas Only)UnitedHealthcare2026-10-01
    Non-Covered Genetic Panel TestsProvidence Health Plan2026-10-01

    Related Codes

    CPT-81105-HPA-1-PLATELET-ANTIGEN-1-GENOTYPING-ITGB3-CD61

    CPT 81105: HPA-1 (ITGB3/CD61) Genotyping, Technical Component

    CPT-81106-HPA-2-T145M-GENETIC-ALLELE-ANALYSIS

    CPT 81106: HPA-2 (T145M) Platelet Antigen Genotyping

    CPT-81107-HPA-3-GENETIC-ANALYSIS-TECHNICAL-COMPONENT

    CPT 81107: HPA‑3 (I843S) Platelet Antigen Genotyping

    CPT-81108-HPA-4-R143Q-GENOTYPING

    CPT 81108: HPA-4 (R143Q) Genotyping

    CPT-81109-HPA-5-K505E-GENETIC-ANALYSIS

    CPT 81109: HPA-5 (K505E) Genotyping Test

    CPT-81110-HPA-6-R489Q-GENOTYPING

    CPT 81110: HPA-6 (R489Q) Genotyping, Technical Component

    CPT-81111-HPA-9-V837M-ALLELE-ANALYSIS

    CPT 81111: HPA-9 (V837M) Genotyping, Technical Test

    CPT-81112-HPA-15-GENETIC-ANALYSIS-S682Y

    CPT 81112: HPA-15 (S682Y) Platelet Antigen Genotyping

    CPT-81120-IDH1-MOLECULAR-DIAGNOSTIC-TEST

    CPT 81120: IDH1 Mutation Detection, Technical Component

    CPT-81161-DMD-GENE-DELETION-DUPLICATION-ANALYSIS

    CPT 81161: Dystrophin (DMD) Gene Deletion/Duplication Analysis

    Showing 1–10 of 199

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    Frequently Asked Questions

    References

    1. 1.CPT® Codes and Descriptions. AAPC. Retrieved Aug 11, 2026.Maintains the CPT code set's official descriptions and guidelines, licensed from the American Medical Association, used as the definitional source for CPT codes on this page.
    2. 2.HCPCS Quarterly Update. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's quarterly release of HCPCS Level II codes and short/long descriptors, the source for HCPCS code definitions and update history.
    3. 3.ICD-10-CM Full Code List. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's complete ICD-10-CM diagnosis code list, used to cross-reference diagnosis codes associated with this procedure or service.
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