Summary & Overview
CPT 0159U: mRNA Sequence Analysis of MSH2 (CustomNext® + RNA)
CPT code 0159U is a Proprietary Laboratory Analyses (PLA) code that identifies the Ambry Genetics® CustomNext® + RNA: MSH2 assay for mRNA sequence analysis of the MSH2 gene, reported alongside the primary full-sequence analysis code. PLA codes like 0159U matter nationally because they designate single-manufacturer or single-lab tests that can affect coding specificity, payer coverage decisions, and claims processing for molecular diagnostics. This code is used in the context of genetic and hereditary cancer testing and influences clinical interpretation when RNA-based analysis supplements DNA sequencing.
Key payers covered in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find an overview of clinical context for RNA-based MSH2 testing, payer coverage considerations for a PLA-designated assay, and where this service is typically performed. The publication outlines benchmarking and policy implications relevant to proprietary laboratory codes, including how PLA status can shape coding practices, claim adjudication, and communication between laboratories and payers. Data not available in the input includes reimbursement rates, payer-specific coverage policies, associated taxonomies, ICD-10 diagnoses, and related codes.
Billing Code Overview
CPT code 0159U is a Proprietary Laboratory Analyses (PLA) code for the CustomNext® + RNA: MSH2 test from Ambry Genetics®. The code applies specifically to mRNA sequence analysis of the MSH2 gene when reported in conjunction with the primary code for full sequence analysis. This PLA code identifies a single manufacturer-specific laboratory assay rather than a broadly available test.
Service type: Molecular diagnostic testing — mRNA sequence analysis of MSH2
Typical site of service: Independent clinical laboratory or reference molecular diagnostics laboratory
Clinical & Coding Specifications
Clinical Context
A 42-year-old patient with a personal and family history suspicious for Lynch syndrome is referred for hereditary cancer genetic testing. The ordering clinician (geneticist or oncologist) requests full germline sequence analysis of mismatch repair genes and adds targeted mRNA analysis for the MSH2 gene to evaluate for splice-altering variants or aberrant transcript production. A blood sample is collected at an outpatient phlebotomy site or in a clinic, sent to Ambry Genetics® for testing. The laboratory performs the primary full sequence DNA analysis (reported under the primary CPT for full sequence analysis) and the proprietary CustomNext® + RNA: MSH2 assay reported with PLA code 0159U to provide mRNA sequence analysis results that clarify variant pathogenicity. Results are reported to the ordering provider and integrated into clinical decision-making for risk assessment, surveillance, and management. Typical sites of service include outpatient clinics, ambulatory surgical centers for pre-test counseling, and centralized clinical laboratories where the test is performed.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
26 | Professional component | When reporting only the professional interpretation component if separated by the lab or physician. |