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    v1.0.28
    OpenPayerBilling CodesGenetic Analysis ProceduresCPT cpt-81336-smn1-full-gene-sequencing
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    CPT 81336: SMN1 Gene Sequencing, Telomeric

    CPT code 81336 describes a laboratory molecular genetics test in which the technical component sequences the entire SMN1 (survival of motor neuron 1) gene at the telomeric region to detect sequence variants; service type: molecular diagnostic sequencing; typical site of service: clinical molecular diagnostics laboratory / reference lab.

    For related coverage guidance, see recent payer policy updates: RTM Testing of Homocysteine Metabolism-Related Conditions, Multimarker Serum Testing Related to Ovarian Cancer, Genomic Profiling for Selecting Targeted Cancer Therapies.

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    Table of contents

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    Clinical & Coding Specifications

    Clinical Context

    A typical patient is an infant or young child with suspected spinal muscular atrophy (SMA) based on hypotonia, progressive muscle weakness, delayed motor milestones, or family history of SMA. The specimen (usually blood or buccal swab) is collected in an outpatient clinic, pediatric neurology office, or genetic counseling visit. The sample is sent to a molecular genetics laboratory where a laboratory analyst performs full gene sequencing of the telomeric survival motor neuron 1 gene using next-generation sequencing or Sanger confirmatory testing to detect point mutations, small insertions/deletions, and sequence-level variants. Results are reported to the ordering clinician and genetic counselor; positive or uncertain findings prompt confirmatory testing, cascade testing of family members, or discussion of treatment options and enrollment in disease-specific registries. Typical site of service: outpatient clinic, specialty clinic (pediatric neurology or genetics), or reference molecular diagnostic laboratory.

    Related CPT Codes

    CPT CodeDescriptionRelationship to This Procedure
    81220SMN1 and SMN2 gene analysis, quantification of gene copy number (e.g., deletion/duplication analysis)Performed alongside sequencing to detect exon deletions or copy number variants not detected by sequencing; complementary for SMA diagnosis.
    81479Unlisted molecular pathology procedureUsed when a specific sequence analysis does not have a precise CPT correlate; rarely used if novel methods are applied.
    81162APC gene full sequence analysis (example sequencing code)Example of full gene sequencing CPTs; demonstrates similar billing and laboratory workflow as sequencing of SMN1.
    88360Immunohistochemistry (IHC), per single antibody stainNot typically used for SMN1 sequencing but may be performed in related neuromuscular tissue assessments.
    G0452Laboratory test management fee (Medicare)May be used in specific Medicare billing scenarios for molecular test ordering and coordination.

    Related Modifiers

    7 rows

    ModifierDescriptionWhen to Use
    26Modifier 26 (Professional Component) identifies and bills only the professional portion of a split service — the physician’s interpretation, report, and medical judgment — when the technical…- Use CPT Modifier -26 when you are billing only the professional component (PC) of a split‑bill eligible service—i.e., you performed the physician interpretation, medical judgment and prepared a…
    90Modifier ‑90 (Reference/Outside Laboratory) indicates that a laboratory test was performed by an entity other than the treating or reporting provider. The American Medical Association defines…- Use CPT modifier -90 when a laboratory test is performed by an outside/reference laboratory (an entity other than the treating or reporting physician or qualified professional) and the claim needs…
    91Modifier 91 — “Repeat Clinical Diagnostic Laboratory Test” — is appended when the exact same CPT laboratory test is performed more than once for the same patient on the same day because serial,…- Use modifier 91 when the exact same CPT laboratory test is performed more than once on the same patient on the same date because serial or repeated testing is medically necessary to monitor…
    59Modifier 59 indicates a distinct procedural service when two procedures that are not normally billed together are clinically and procedurally separate. The CPT definition (as reiterated by CMS)…- Use modifier -59 to report a distinct procedural service when documentation supports that the procedure reported is not normally billed together with another service on the same day because of a…
    22Modifier –22 (Increased Procedural Services) is used when a reported procedure is substantially more extensive than normally required. The CPT Manual and CMS state it may be appended only when the…- When to use: Append modifier -22 to a procedural CPT code when the service performed is substantially more extensive than the usual service described by that code — i.e., the procedure required…
    52Modifier ‑52 (Reduced Services) indicates that a service or procedure was partially reduced or omitted at the provider’s discretion, allowing reporting of the basic procedure number with a qualifier…- Use modifier -52 when a physician or qualified health professional electively reduces or omits part of a procedure or service (for example, performing fewer required views or omitting a portion of…
    53Modifier 53 (Discontinued Procedure) signals that a surgical or diagnostic service was begun by the physician but terminated because of extenuating circumstances that threatened the patient’s…- Use modifier -53 when a physician/qualified healthcare professional has started a surgical or diagnostic procedure (e.g., anesthesia administered, incision or scope insertion) and then discontinues…

    Related Provider Taxonomies

    8 rows

    Taxonomy CodeSpecialtyNotes
    207RG0100XGastroenterology PhysicianAn internist who specializes in diagnosis and treatment of diseases of the digestive organs including the stomach, bowels, liver and gallbladder. This…
    2084P0800XPsychiatry PhysicianA Psychiatrist specializes in the prevention, diagnosis, and treatment of mental disorders, emotional disorders, psychotic disorders, mood disorders, …
    207L00000XAnesthesiology PhysicianAn anesthesiologist is trained to provide pain relief and maintenance, or restoration, of a stable condition during and immediately following an opera…
    208000000XPediatrics PhysicianA pediatrician is concerned with the physical, emotional and social health of children from birth to young adulthood. Care encompasses a broad spectru…
    133VN1005XRenal Nutrition Registered DietitianAn individual who is a Board Certified Specialist in Renal Nutrition and works directly with adult and/or pediatric patients with acute kidney injury,…
    385HR2055XChild Mental Illness Respite CareA facility or distinct part of a facility that provides short term, residential care to children, diagnosed with mental illness, as respite for the re…
    2279G0305XGeriatric Care Registered Respiratory TherapistCare of older patients who have age and/or disease related decremental pulmonary changes. Diagnosis and treatment is very important for this group si…
    207LP3000XPediatric Anesthesiology PhysicianAn anesthesiologist who has had additional skill and experience in and is primarily concerned with the anesthesia, sedation, and pain management needs…

    Related ICD-10-CM Codes

    27 rows

    ICD-10-CM CodeDescription
    F82Specific developmental disorder of motor function
    G12.0Infantile spinal muscular atrophy, type I [Werdnig-Hoffman]
    G12.21Amyotrophic lateral sclerosis
    G31.9Degenerative disease of nervous system, unspecified
    G60.9Hereditary and idiopathic neuropathy, unspecified
    M62.81Muscle weakness (generalized)
    M62.9Disorder of muscle, unspecified
    O35.2XX0Maternal care for (suspected) hereditary disease in fetus, not applicable or unspecified
    P94.2Congenital hypotonia
    Q87.89Other specified congenital malformation syndromes, not elsewhere classified

    Showing 1–10 of 27

    Related Payer Policy Updates

    Specialty: Genetic & Molecular Testing1 / 3

    10 rows

    PolicyPayerEffective Date
    RTM Testing of Homocysteine Metabolism-Related ConditionsOscar Health2026-10-01
    Multimarker Serum Testing Related to Ovarian CancerBlue Cross Blue Shield - Rhode Island2026-09-01
    Genomic Profiling for Selecting Targeted Cancer TherapiesBlue Cross Blue Shield - Rhode Island2026-09-01
    Whole Exome and Whole Genome Sequencing for Diagnosis of Genetic DisordersBlue Cross Blue Shield - Rhode Island2026-09-01
    Biomarker and Genetic/Molecular Testing Coverage and Prior AuthorizationBlue Cross Blue Shield - Rhode Island2026-09-01
    Non-Invasive Prenatal Testing (NIPT)univerahealthcare2026-08-17
    Lumizyme (alglucosidase alfa) — Pompe Disease (acid alpha‑glucosidase deficiency)Cigna2026-08-15
    Molecular Oncology Testing for Solid Tumor Cancer Diagnosis, Prognosis, and Treatment DecisionsColorado Rocky Mountain Health Plans2026-08-01
    Carrier Testing Panels for Genetic DiseasesColorado Rocky Mountain Health Plans2026-08-01
    Molecular Oncology Testing for Hematologic Cancer Diagnosis, Prognosis, and Treatment DecisionsColorado Rocky Mountain Health Plans2026-08-01

    Related Codes

    CPT-81105-HPA-1-PLATELET-ANTIGEN-1-GENOTYPING-ITGB3-CD61

    CPT 81105: HPA-1 (ITGB3/CD61) Genotyping, Technical Component

    CPT-81106-HPA-2-T145M-GENETIC-ALLELE-ANALYSIS

    CPT 81106: HPA-2 (T145M) Platelet Antigen Genotyping

    CPT-81107-HPA-3-GENETIC-ANALYSIS-TECHNICAL-COMPONENT

    CPT 81107: HPA‑3 (I843S) Platelet Antigen Genotyping

    CPT-81108-HPA-4-R143Q-GENOTYPING

    CPT 81108: HPA-4 (R143Q) Genotyping

    CPT-81109-HPA-5-K505E-GENETIC-ANALYSIS

    CPT 81109: HPA-5 (K505E) Genotyping Test

    CPT-81110-HPA-6-R489Q-GENOTYPING

    CPT 81110: HPA-6 (R489Q) Genotyping, Technical Component

    CPT-81111-HPA-9-V837M-ALLELE-ANALYSIS

    CPT 81111: HPA-9 (V837M) Genotyping, Technical Test

    CPT-81112-HPA-15-GENETIC-ANALYSIS-S682Y

    CPT 81112: HPA-15 (S682Y) Platelet Antigen Genotyping

    CPT-81120-IDH1-MOLECULAR-DIAGNOSTIC-TEST

    CPT 81120: IDH1 Mutation Detection, Technical Component

    CPT-81121-IDH2-MOLECULAR-DIAGNOSTIC-TEST

    CPT 81121: IDH2 Mutation Detection, Technical Component

    Showing 1–10 of 199

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    Frequently Asked Questions

    References

    1. 1.CPT® Codes and Descriptions. AAPC. Retrieved Aug 11, 2026.Maintains the CPT code set's official descriptions and guidelines, licensed from the American Medical Association, used as the definitional source for CPT codes on this page.
    2. 2.HCPCS Quarterly Update. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's quarterly release of HCPCS Level II codes and short/long descriptors, the source for HCPCS code definitions and update history.
    3. 3.ICD-10-CM Full Code List. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's complete ICD-10-CM diagnosis code list, used to cross-reference diagnosis codes associated with this procedure or service.
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