Summary & Overview
CPT 81189: Full CSTB Gene Sequencing, Technical Component
CPT code 81189 denotes the technical laboratory procedure to sequence the entire cystatin B gene (CSTB). This molecular diagnostic code captures the laboratory analytic work required to generate and process full-gene sequence data for CSTB, a gene relevant to hereditary neurologic and myoclonic conditions. nationally, precise coding for gene sequencing impacts claim adjudication, coverage determinations, and access to diagnostic genetic information.
Key payers in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise overview of what CPT code 81189 represents, the typical clinical and laboratory context for use, and the practical implications for billing and coverage workflows. The publication outlines common billing modifiers associated with laboratory technical components and summarizes where CPT code 81189 fits within molecular diagnostics service lines.
This summary provides clinical context for when full-gene CSTB sequencing is likely ordered, clarifies the typical site of service, and identifies information gaps where input data was not provided. The material is intended for coding professionals, laboratory billing staff, and payers involved in genetic test coverage and claims processing.
Billing Code Overview
CPT code 81189 describes laboratory analysis of the entire gene sequence for the cystatin B gene (CSTB). The service is a molecular diagnostic sequencing test in which a laboratory analyst performs the technical component to generate and analyze the full CSTB gene sequence.
Service Type: Molecular diagnostic sequencing (technical component)
Typical Site of Service: Clinical laboratory or specialized molecular diagnostics facility
Clinical & Coding Specifications
Clinical Context
A typical patient is a child or young adult with progressive, stimulus-sensitive myoclonus, ataxia, and cognitive decline where clinicians suspect Unverricht–Lundborg disease or other CSTB-related progressive myoclonic epilepsy. The referring clinician (neurologist, pediatric neurologist, or geneticist) documents the history, family history, and neurologic exam and orders comprehensive sequencing of the cystatin B gene (CSTB). A blood or saliva specimen is collected in the outpatient laboratory or ambulatory clinic and sent to a clinical molecular diagnostics laboratory. The molecular laboratory analyst performs 81189 to sequence the entire CSTB coding region and relevant intronic boundaries, interprets technical quality metrics, and generates a technical report. The laboratory may also perform variant confirmation using orthogonal methods and the ordering provider receives an integrated report including clinical interpretation from a lab director or molecular geneticist. Typical site of service is an outpatient clinical laboratory, reference molecular diagnostics laboratory, or hospital-based molecular pathology lab. Billing uses the technical component; if a separate professional interpretation is billed, an appropriate professional CPT (e.g., a molecular pathology interpretation code) may be reported by the physician or laboratory director.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|