Summary & Overview
CPT 81181: ATXN7 (ataxin 7) Repeat Expansion Detection
CPT code 81181 designates a laboratory molecular test that detects expanded allele sequences in the ataxin 7 gene (ATXN7). Genetic testing for repeat expansions in ATXN7 is clinically important for diagnosing hereditary neurodegenerative syndromes and guiding downstream clinical management, genetic counseling, and family testing. Nationally, access to and coverage of specialized molecular assays affects diagnostic timelines and resource allocation in clinical genetics and neurology.
Key payers in the analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise explanation of what this code represents, the clinical context for ATXN7 expansion testing, and what typical service delivery looks like (laboratory-based technical testing). The publication outlines benchmarks and policy-relevant points for payer coverage and coding practice, highlights common billing modifiers and operational considerations for lab services, and summarizes areas where documentation and test selection drive billing outcomes. The content is intended for national audiences including health policy analysts, coding and billing teams, laboratory administrators, and clinical genetics stakeholders.
Billing Code Overview
CPT code 81181 describes a molecular laboratory procedure in which a lab analyst performs the technical testing to detect the presence of changes in the gene ataxin 7 (ATXN7) to identify abnormal alleles involving expanded sequences. This service is a genetic diagnostic test focused on detecting repeat expansions associated with clinical conditions involving ATXN7.
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Service type: Genetic molecular laboratory testing (technical component)
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Typical site of service: Clinical molecular diagnostics laboratory or hospital laboratory setting
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Clinical & Coding Specifications
Clinical Context
A typical patient is an adult presenting to a neurology clinic with progressive cerebellar ataxia, slurred speech, gait instability, and a family history suggestive of autosomal dominant spinocerebellar ataxia. The neurologist documents clinical features and orders molecular testing for expanded CAG repeat alleles in the ATXN7 gene to confirm a clinical diagnosis of Spinocerebellar Ataxia Type 7 (SCA7). A genetic counselor conducts pre-test counseling, obtains informed consent, and collects a blood specimen. The specimen is shipped to a molecular diagnostics laboratory where a laboratory analyst performs the technical testing described by 81181 to detect expanded ATXN7 alleles. Results are reported to the ordering neurologist and genetic counselor; post-test genetic counseling is provided to discuss implications, family testing, and reproductive options. Typical site of service: outpatient neurology clinic for counseling and collection; reference clinical molecular laboratory for testing.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
26 | Professional component | Use when billing for the interpreting professional component separate from the laboratory technical component. |
TC |