Summary & Overview
CPT 0605U: Tryptase Gene Copy Number Analysis by dPCR
CPT code 0605U designates a Proprietary Laboratory Analyses (PLA) molecular test: Tryptase Gene Copy Number Analysis by digital PCR from Virant Diagnostics Inc. The assay quantifies copies of the TPSAB1 gene from whole blood and reports genotype-specific alpha tryptase copy number with algorithmic classification as normal or abnormal. As a PLA code, 0605U applies to a single, manufacturer-specific test and is relevant to precision diagnostics, hereditary tryptase-associated conditions, and downstream clinical management considerations.
Key national payers in scope include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a national-level briefing on the clinical purpose of the test, payer coverage landscape, and the policy and coding context for a PLA molecular diagnostic. The publication outlines common billing considerations for laboratory genetic tests, highlights how PLA designation affects coding and uniqueness of the service, and summarizes expected sites of service and specimen type. Data not available in the input will be noted where applicable.
Billing Code Overview
CPT code 0605U is a Proprietary Laboratory Analyses (PLA) code for Tryptase Gene Copy Number Analysis by digital PCR (dPCR) performed by Virant Diagnostics Inc. The test determines the copy number of the TPSAB1 gene using digital polymerase chain reaction on DNA extracted from whole blood. Results include genotype-specific interpretation of alpha tryptase copy number and are classified as normal or abnormal using a provided algorithm.
Service type: Laboratory genetic testing — molecular diagnostic (digital PCR) for gene copy number analysis
Typical site of service: Clinical laboratory or reference diagnostic laboratory, with specimen collection from whole blood
Clinical & Coding Specifications
Clinical Context
A typical patient is an adult referred by an allergist or immunologist for evaluation of suspected hereditary alpha tryptasemia after clinical features such as recurrent idiopathic anaphylaxis, unexplained systemic mast cell activation symptoms (flushing, abdominal pain, diarrhea, urticaria), elevated baseline serum tryptase, or a family history of elevated tryptase. The ordering clinician collects whole blood in EDTA and sends the specimen to Virant Diagnostics Inc. for 0605U Tryptase Gene Copy Number Analysis by digital PCR. The laboratory performs dPCR to quantify TPSAB1 alpha-tryptase copy number; results are reported as genotype-specific copy number with algorithmic classification as normal or abnormal. The report is reviewed by the ordering clinician to integrate genetic results with clinical findings for diagnostic clarification and family counseling. Typical site of service is an outpatient clinic, specialty allergy/immunology office, or a reference clinical laboratory; specimen collection occurs in a phlebotomy clinic or outpatient lab service.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
26 | Professional component | Use when billing separate professional interpretation of the laboratory report (rare for PLA codes that are fully bundled to the performing lab). |