Summary & Overview
CPT 81339: MPL Gene Sequencing for Myeloproliferative Neoplasms
CPT code 81339 represents molecular testing that sequences portions of the MPL gene (such as exon 10) from a patient specimen to detect variants linked to myeloproliferative neoplasms (MPN), including essential thrombocythemia in patients without the common JAK2 V617F mutation. Nationally, this code covers targeted genomic analysis used in diagnostic workups for suspected MPN and informs downstream clinical decisions about diagnosis and monitoring. Key payers discussed include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare.
Readers will find a concise overview of clinical context for MPL testing, the typical laboratory service setting, and the payer landscape for molecular hematology diagnostics. The publication summarizes reimbursement and coverage benchmarks, common modifiers encountered, and policy updates that affect molecular diagnostic billing. Additionally, it outlines what clinicians and billing teams should expect in claims handling and documentation for CPT code 81339, and highlights areas where authorization or medical necessity language commonly influences payer determinations. Data not provided in the input (for example, specific coverage criteria by payer or associated ICD-10 codes) is noted as unavailable.
Billing Code Overview
CPT code 81339 describes a laboratory molecular test that analyzes specific gene sequences of the MPL (MPL proto–oncogene, thrombopoietin receptor) gene, for example exon 10, on a specimen such as blood. This testing identifies MPL variants that may be associated with myeloproliferative neoplasms (MPN), including essential thrombocythemia (ET), particularly in patients who are negative for the JAK2 V617F mutation.
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Service type: Molecular diagnostic laboratory test (technical and analytical performance on patient specimen)
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Typical site of service: Clinical laboratory or reference laboratory performing molecular diagnostics on blood or other suitable specimens
Clinical & Coding Specifications
Clinical Context
A 58-year-old patient with persistent thrombocytosis and clinical concern for a myeloproliferative neoplasm presents to hematology after testing negative for the common JAK2 V617F mutation. The hematologist orders targeted molecular testing of the MPL gene to evaluate for pathogenic variants (commonly in exon 10) that can cause essential thrombocythemia or primary myelofibrosis. Peripheral blood is collected in appropriate anticoagulant tubes and sent to a molecular diagnostics laboratory. In the lab, a molecular technologist extracts genomic DNA, performs PCR amplification and sequencing (or allele-specific testing) of the MPL gene region, interprets technical results, and the laboratory director issues a finalized report that includes clinical interpretation for the ordering hematologist. Typical site of service is an outpatient phlebotomy collection center or hospital outpatient clinic with testing performed in a Clinical Laboratory Improvement Amendments (CLIA)-certified molecular diagnostics laboratory.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
26 | Professional component | Use when billing only the laboratory professional interpretation component separate from technical testing if allowed. |
59 |