CPT 0027U: JAK2 Exons 12–15 Sequencing (JAKXR), Mayo Clinic

CPT code 0027U is a Proprietary Laboratory Analyses (PLA) code for the Mayo Clinic’s JAK2 Exons 12–15 Sequencing (JAKXR) test, a molecular diagnostic sequencing assay used to detect variants in JAK2 associated with myeloproliferative and other hematologic disorders. As a PLA code, 0027U identifies a single manufacturer- or lab-specific test, which matters for payer coverage, coding specificity, and lab-level reporting across the United States.

Key payers discussed include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise overview of the clinical purpose of the test, the typical laboratory setting for service delivery, and the payer landscape relevant to molecular diagnostics. The publication also outlines common billing modifiers and highlights where input data is not available.

This analysis is designed to inform coding staff, laboratory billing teams, and policy analysts about the code’s clinical role, expected sites of service, and the payers commonly involved in reimbursement discussions. Content includes benchmarks and policy context when available, but specific utilization and payer-specific coverage details are not provided in the input and are noted as unavailable.

Billing Code Overview

CPT code 0027U is a Proprietary Laboratory Analyses (PLA) code that describes a single, specific laboratory test: the JAK2 Exons 12 to 15 Sequencing (JAKXR) assay developed by the Mayo Clinic. The code represents sequencing of JAK2 exons 12–15 to detect variants associated with hematologic disorders.

Service Type: Molecular diagnostic sequencing test

Typical Site of Service: Clinical laboratory / reference laboratory

Data not available in the input.

Clinical Context

A 58-year-old patient with persistent erythrocytosis and abnormal myeloproliferative features is evaluated by a hematologist. Prior initial testing for the canonical JAK2 V617F mutation and JAK2 Exon 14 testing were negative or inconclusive. The clinician orders the Mayo Clinic JAK2 Exons 12–15 Sequencing test (0027U) to detect less common JAK2 exon variants that can explain erythrocytosis, thrombocytosis, or unexplained splenomegaly and to guide diagnosis of polycythemia vera, other myeloproliferative neoplasms, or targeted therapy decisions.

At specimen collection, a peripheral blood draw is performed and sent to the laboratory with the appropriate test requisition. The lab performs targeted sequencing of JAK2 exons 12–15, analyzes variant allele fraction, and issues a report describing pathogenic, likely pathogenic, or variants of uncertain significance. The ordering provider documents the clinical indication, prior molecular testing, and how results will inform diagnosis, prognosis, or treatment selection. Typical sites of service are outpatient phlebotomy centers, hospital outpatient laboratories, and reference laboratory facilities that perform proprietary testing.

Coding Specifications

Modifier	Description	When to Use
`90`	Reference (Outside) Laboratory	When the test is performed by an outside or reference laboratory and billed through another provider.

Taxonomy Code	Specialty	Notes
2080P0200X	Hematology	Hematologists commonly order JAK2 sequencing for suspected myeloproliferative neoplasms.
207Q00000X	Pathology	Pathologists sign out molecular diagnostic reports and interpret sequencing results.
207K00000X	Clinical Laboratory	Clinical laboratory directors oversee test validation and result reporting for proprietary assays.
2085R0206X	Medical Oncology	Medical oncologists may order sequencing when hematologic malignancy management or targeted therapy is considered.

Related Diagnoses

ICD-10 Code	Description	Clinical Relevance
`D45`	Polycythemia vera	JAK2 exon mutations (including exons 12–15) are diagnostic drivers for polycythemia vera when V617F is absent.
`D47.3`	Essential (primary) thrombocythemia	JAK2 exon variants can be present in patients with thrombocytosis and help subtype myeloproliferative neoplasms.
`D47.1`	Chronic myeloproliferative disease	Broad category encompassing disorders where extended JAK2 sequencing may clarify molecular etiology.
`R71.8`	Other abnormality of red blood cells	Used when red cell indices suggest unexplained erythrocytosis prompting molecular testing.
`D72.8`	Other specified disorders of white blood cells	Applied when leukocyte abnormalities are present and molecular evaluation is pursued.

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`81445`	Oncology (somatic) hotspot panel, targeted sequence analysis	May be ordered when broader somatic mutation panels are needed in addition to targeted JAK2 exon sequencing.
`81479`	Unlisted molecular pathology procedure	Used when a specific proprietary assay lacks an exact CPT equivalent and only when billing guidance permits.
`88360`	Morphometric analysis, malignant cells (special stain/immunohistochemistry related)	Performed on tissue samples when histopathology and molecular testing are coordinated; not routine for blood-based JAK2 sequencing.
`G0452`	Unlisted molecular pathology or lab test (Medicare-specific)	May be used in contexts where Medicare requires alternate coding for proprietary lab tests.

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Summary & Overview