Summary & Overview
CPT 81331: Methylation Analysis of SNRPN and UBE3A
CPT code 81331 represents a laboratory molecular diagnostic test that performs methylation analysis of the SNRPN and UBE3A genes. This test is used to detect gene-specific methylation changes that can be relevant in genetic and neurologic disorders where imprinting or methylation status is clinically significant. Nationally, accurate coding and reimbursement for specialized molecular tests like 81331 matters for laboratory operations, patient access to genetic diagnostics, and payer coverage policies.
Key payers in this review include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise overview of payer coverage considerations, typical sites of service, and the clinical context in which the test is ordered. The publication outlines benchmarks for utilization and coding practice where available, summarizes relevant policy developments affecting molecular diagnostic billing, and provides clinical context about what the test measures and why it is ordered.
This summary is designed for laboratory billing managers, clinicians who order genetic testing, and payer policy analysts seeking a national view of CPT code 81331 — what the code represents, who covers it, and the kinds of operational and policy information stakeholders should consider.
Billing Code Overview
CPT code 81331 describes a laboratory methylation analysis that detects methylation changes in two genes: SNRPN (small nuclear ribonucleoprotein polypeptide N) and UBE3A (ubiquitin–protein ligase E3A). The service involves the technical performance of the molecular laboratory test to evaluate gene-specific methylation patterns.
Service type: Molecular diagnostic / Laboratory test
Typical site of service: Clinical laboratory or independent diagnostic testing facility (IDTF)
Clinical & Coding Specifications
Clinical Context
A 2-year-old child with global developmental delay, absence of speech, ataxic movements, and a history of seizures is referred by a pediatric neurologist for molecular testing to evaluate for Angelman syndrome. A genetics counselor obtains informed consent and a peripheral blood sample is collected at an outpatient phlebotomy site. The sample is sent to the molecular diagnostics laboratory where a technologist performs methylation analysis targeting the imprinting region on chromosome 15 involving the small nuclear ribonucleoprotein polypeptide N (SNRPN) and ubiquitin–protein ligase E3A (UBE3A). The laboratory runs controls, performs the technical assay, interprets results, and issues a report to the ordering clinician. Typical sites of service include an outpatient hospital lab, independent reference laboratory, or an accredited molecular diagnostics laboratory within an academic medical center.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
26 | Professional component | When billing only the professional interpretation component if separated from the technical lab fee |
TC |