CPT 81299 MSH6 Familial Test Reimbursement

CPT code 81299 represents a targeted molecular genetic test to detect specific familial mutations in the MSH6 gene. This single-gene, family-directed assay is used when a pathogenic or likely pathogenic variant has already been identified in a patient's family member and a focused test is needed to determine the patient’s carrier or affected status. Nationally, such tests are important for inherited cancer risk assessment and precision prevention strategies because they allow for efficient confirmation of known familial variants without broader genomic sequencing.

Key payers commonly included in analyses of molecular testing coverage are Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find benchmarks for payer coverage policies, typical sites of service, and clinical context for using targeted familial testing versus broader gene-panel or exome approaches. The publication also summarizes coding considerations, common modifiers used with laboratory services, and the clinical scenarios in which a targeted MSH6 familial test is most applicable.

This summary is intended to provide clinicians, billing professionals, and policy analysts with a concise national overview of the code’s clinical role, payer landscape, and what to expect in documentation and service delivery for targeted familial genetic testing.

Billing Code Overview

CPT code 81299 describes a targeted molecular test performed by a laboratory analyst to detect the presence of specific family-known mutations in the MSH6 gene (mutS homolog 6 [E. coli]). This service is a molecular genetic test focused on identifying familial variants in a single gene when those variant(s) are already known in the patient's relatives.

Service Type: Targeted molecular genetic testing / single-gene familial mutation analysis

Typical Site of Service: Clinical molecular diagnostics laboratory or reference genetic testing laboratory

Data not available in the input for payers, associated taxonomies, ICD-10 diagnoses, related codes, and service line.

Clinical Context

A 34-year-old patient with a first-degree relative previously identified with a pathogenic MSH6 gene mutation presents for targeted familial mutation testing. The clinical workflow begins with genetic counseling to review family history and informed consent. A specimen, typically peripheral blood or buccal swab, is collected at an outpatient laboratory or hospital phlebotomy service. The molecular diagnostics laboratory performs targeted analysis to detect the specific familial MSH6 variant. Results are returned to the ordering geneticist or primary care provider and discussed with the patient during a follow-up genetic counseling visit to review implications for cancer surveillance, risk-reduction strategies, and cascade testing of relatives. Typical site of service is an outpatient clinical laboratory or hospital molecular pathology lab. Service type: targeted familial molecular diagnostic test (single-gene targeted mutation analysis).

Coding Specifications

Modifier	Description	When to Use
`11`	Chief physician or other qualified health care professional service	When the billing practitioner is the primary performing professional for consultative/final interpretation services associated with the test.
`26`	Professional component

Taxonomy Code	Specialty	Notes
`2080P0200X`	Medical Genetics	Providers who order and interpret hereditary cancer genetic testing.
`207Q00000X`	Clinical Molecular Genetics	Laboratory directors and specialists overseeing molecular diagnostic testing.
`207L00000X`	Pathology	Molecular pathology specialists who supervise testing and issuance of reports.
`206RP0400X`	Oncology	Medical oncologists who may order targeted germline testing for cancer predisposition.
`2085R0202X`	Genetic Counseling	Certified genetic counselors who provide pre- and post-test counseling and result disclosure.

Related Diagnoses

ICD-10 Code	Description	Clinical Relevance
`Z15.01`	Genetic susceptibility to malignant neoplasm of colon	Indicates known familial predisposition to colorectal cancer; supports targeted MSH6 familial mutation testing.
`Z15.09`	Genetic susceptibility to other malignant neoplasm	Used when documenting genetic susceptibility to non-colorectal Lynch-related cancers where MSH6 testing is indicated.
`Z80.0`	Family history of malignant neoplasm of digestive organs	Family history that prompts targeted testing for MSH6 familial variants.
`Z80.3`	Family history of malignant neoplasm of breast and genital organs	Relevant when broader hereditary cancer risk assessment includes MSH6 based on family history patterns.
`Z84.81`	Family history of carrier of genetic disease	Documentation of known familial pathogenic variant carrier status which justifies targeted familial testing.
`R79.9`	Abnormal finding of study of blood, unspecified	Occasionally used when abnormal tumor marker or screening triggers genetic evaluation; less specific but associated in workflows.

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`81162`	Mismatch repair genes (eg, MLH1, MSH2, MSH6, PMS2) sequencing; full gene analysis	Broader sequencing panel that may be used when a familial mutation is unknown or comprehensive gene sequencing is indicated instead of targeted familial mutation testing.
`81335`	BRCA1 and BRCA2 full gene sequence analysis	Example of another hereditary cancer gene full-sequence test often performed in parallel for hereditary breast/ovarian cancer risk assessment when family history warrants broader testing.
`81445`	Hereditary colorectal cancer syndrome panel (eg, multi-gene panel)	Multi-gene panel testing that can include MSH6 as part of broader hereditary colorectal cancer predisposition evaluation.
`80500`	Drug assay, qualitative; other (eg, detection of specific variants)	Represents targeted molecular assays; analogous to targeted single-variant detection methods used in familial testing workflows.
`88381`	Microdissection for molecular analysis	Pre-analytic procedure when microdissection is required to enrich sample cellularity prior to molecular testing (occasionally relevant for tissue specimens submitted for germline or somatic testing).

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Summary & Overview

CPT 81299: Targeted Familial Mutation Test for MSH6