Summary & Overview
CPT 81172: AFF2 (ALF) Gene Repeat and Methylation Characterization
CPT code 81172 denotes a specialized molecular laboratory test performed to characterize changes in the ALF transcription elongation factor 2 gene (AFF2), typically clarifying nucleotide repeat expansions or methylation status after an initial abnormal result. This test supports diagnostic clarity for conditions associated with AFF2 alterations and can influence downstream clinical management and genetic counseling. Nationally, molecular characterization codes like 81172 are important as precision diagnostics expand and laboratories refine reporting and billing for targeted genetic analyses.
Key payers addressed include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find an overview of what CPT code 81172 represents clinically, common billing modifiers and service settings, and context on how this test fits into molecular diagnostic workflows. The publication will also cover typical reimbursement considerations, common payer coverage patterns, and coding best practices relevant to laboratory operations and billing teams.
This summary is intended for a national audience of laboratory directors, billing professionals, and health policy analysts seeking concise information on the clinical purpose, operational setting, and payer landscape related to CPT code 81172.
Billing Code Overview
CPT code 81172 describes a technical laboratory procedure performed by a lab analyst to characterize changes in the ALF transcription elongation factor 2 gene (also known as AFF2). The procedure typically targets determination of nucleotide repeat size or methylation status after an initial abnormality has been detected, providing molecular characterization used in diagnostic evaluation.
Service Type: Molecular genetic testing / specialized laboratory analysis
Typical Site of Service: Clinical laboratory or specialized molecular diagnostics laboratory
Clinical & Coding Specifications
Clinical Context
A typical patient is a male or female referred from a genetics clinic or neurology clinic after initial testing suggests an abnormality in the AFF2 (also called FMR2/ALF) locus. The patient may present with developmental delay, intellectual disability, autism spectrum disorder features, or family history of X-linked intellectual disability. Initial screening tests (for example, PCR-based repeat-primed assays or methylation-sensitive testing) have indicated an abnormal CGG trinucleotide repeat expansion or atypical methylation pattern at the AFF2 locus.
The clinical workflow begins with the ordering clinician documenting the indication and submitting a blood sample to a molecular genetics laboratory. A laboratory accessioning technologist assigns the sample and the lab analyst performs the technical molecular test described by 81172 to characterize the nucleotide repeat number and/or methylation status of the AFF2 gene. Results are compiled into a technical report and routed to the ordering provider. A clinical geneticist or genetic counselor interprets the results in the context of phenotype and family history and communicates implications to the patient and family, including recurrence risk and potential need for cascade testing in relatives.
Typical site of service is an outpatient molecular diagnostics laboratory or hospital-based molecular pathology laboratory supporting ambulatory genetics clinics and neurology practices. The procedure is laboratory-focused and rarely performed at the bedside; specimen collection typically occurs in an ambulatory clinic or phlebotomy center.
Coding Specifications
| Modifier | Description | When to Use |
|---|