Summary & Overview
CPT 81185: CACNA1A Full Gene Sequencing
CPT code 81185 denotes comprehensive laboratory sequencing of the CACNA1A gene, a clinically significant test for identifying pathogenic variants associated with neurologic disorders. As a full-gene sequencing technical service, it supports diagnosis, genetic counseling, and management decisions for conditions linked to CACNA1A. Nationally, molecular diagnostic codes like 81185 are important because they underpin coverage determinations, laboratory billing practices, and access to specialty genetic testing. Key payers in the landscape include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. This publication provides readers with a concise reference to the code’s clinical purpose, typical service setting, and payer relevance. Readers will find benchmarks and coverage context where available, a summary of common modifiers, and clinical context for when full-gene sequencing of CACNA1A is employed. The document also highlights policy considerations affecting molecular diagnostics billing and flags areas where input data were not provided. Data not available in the input are explicitly indicated where applicable.
Billing Code Overview
CPT code 81185 describes a laboratory technical service that analyzes the entire gene sequence of the calcium voltage–gated channel subunit alpha1 A gene (CACNA1A). The procedure represents comprehensive sequencing of the gene to detect variants across its full coding region.
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Service type: Clinical laboratory molecular diagnostic test—full gene sequencing
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Typical site of service: Clinical molecular diagnostics laboratory or hospital laboratory performing molecular genetic testing
Clinical & Coding Specifications
Clinical Context
A patient, typically an adult or child with episodic ataxia, familial hemiplegic migraine, early-onset cerebellar atrophy, or unexplained paroxysmal neurologic symptoms, is referred for comprehensive molecular testing of the CACNA1A gene. The clinical workflow begins with a neurology or genetics consultation where the clinician documents family history, neurologic examination findings (e.g., ataxia, migraine with motor aura, transient hemiparesis), and orders full-gene sequencing (CPT 81185). A blood sample is collected at an outpatient phlebotomy site or ambulatory clinic and sent to a reference molecular diagnostics laboratory. The laboratory performs DNA extraction, library preparation, sequencing across the entire CACNA1A coding region and relevant intron–exon boundaries, bioinformatic analysis, and variant interpretation. The lab issues a report classifying variants (pathogenic, likely pathogenic, variant of uncertain significance, likely benign, benign) with recommended follow-up such as confirmatory testing or familial cascade testing. Typical sites of service include hospital outpatient laboratories, independent reference labs, and genetics laboratories; ordering providers are usually neurologists, clinical geneticists, or pediatric neurologists. Turnaround time varies by urgency and payer authorization, often ranging from 2 to 8 weeks, with STAT or expedited processing available when justified.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
26 | Professional component |