CPT® Code 81329

Official Description

SMN1 (survival of motor neuron 1, telomeric) (eg, spinal muscular atrophy) gene analysis; dosage/deletion analysis (eg, carrier testing), includes SMN2 (survival of motor neuron 2, centromeric) analysis, if performed

Common Language Description

The CPT® Code 81329 pertains to the molecular genetic testing of the SMN1 (survival of motor neuron 1, telomeric) gene, which is crucial in the context of spinal muscular atrophy (SMA), a serious neuromuscular disorder characterized by the degeneration of motor neurons. This testing includes dosage and deletion analysis, which is essential for carrier testing. The analysis may also encompass the SMN2 (survival of motor neuron 2, centromeric) gene if it is performed. The SMN1 gene is located on the long (q) arm of chromosome 5 at position 13.2 (5q13.2) and is responsible for producing a protein that plays a vital role in the transport of signals through motor neurons to voluntary muscles, which are necessary for functions such as walking, talking, and swallowing. The protein produced by the SMN1 gene is fully functional and accounts for approximately 85-90% of the total SMN protein in the body, while the SMN2 gene contributes the remaining 10-15% through its production of two protein isoforms, only one of which is functional. The presence of multiple copies of the SMN1 and SMN2 genes can influence the risk of transmitting SMA to offspring, with deletions in both copies of the SMN1 gene being present in 95% of cases. The testing provided by code 81329 is instrumental in identifying deletion mutations and counting gene copies, which aids in understanding the genetic landscape of SMA and its inheritance patterns.

1. Indications

The procedure associated with CPT® Code 81329 is indicated for the following conditions:

Carrier Testing This testing is performed to determine if an individual carries mutations in the SMN1 gene that could be passed on to offspring, thereby assessing the risk of spinal muscular atrophy (SMA) in future generations.
Diagnosis of Spinal Muscular Atrophy The analysis is utilized to confirm a diagnosis of SMA in individuals presenting with symptoms consistent with the disease, such as muscle weakness and atrophy.
Family History of SMA Individuals with a known family history of spinal muscular atrophy may undergo this testing to identify potential genetic mutations that have been previously documented in affected family members.

2. Procedure

The procedure for CPT® Code 81329 involves several key steps to ensure accurate genetic analysis:

Sample Collection A biological sample, typically blood or saliva, is collected from the individual undergoing testing. This sample contains the DNA necessary for genetic analysis.
DNA Extraction The DNA is extracted from the collected sample using standard laboratory techniques to isolate the genetic material for further analysis.
Dosage/Deletion Analysis The extracted DNA is subjected to dosage and deletion analysis specifically targeting the SMN1 gene. This step involves assessing the number of gene copies present and identifying any deletion mutations that may be present in the gene.
SMN2 Analysis (if performed) If applicable, the analysis may also include the SMN2 gene to provide additional context regarding the genetic landscape and potential compensatory mechanisms in SMA.
Data Interpretation The results of the genetic analysis are interpreted to determine the presence of mutations, the number of gene copies, and any implications for the individual’s risk of SMA or carrier status.

3. Post-Procedure

After the completion of the genetic testing associated with CPT® Code 81329, the following post-procedure considerations are important:

Patients may receive genetic counseling to discuss the implications of their test results, particularly if they are found to be carriers of mutations in the SMN1 gene. This counseling can help individuals understand their risk of having children with spinal muscular atrophy and the potential need for further testing or monitoring. Additionally, healthcare providers may recommend follow-up testing for family members if a mutation is identified, to assess their risk and inform family planning decisions. The results of the analysis may also guide clinical management and treatment options for individuals diagnosed with SMA.

Short Descr	SMN1 GENE DOS/DELETION ALYS
Medium Descr	SMN1 GENE ANALYSIS DOSAGE/DELET ALYS W/SMN2 ALYS
Long Descr	SMN1 (survival of motor neuron 1, telomeric) (eg, spinal muscular atrophy) gene analysis; dosage/deletion analysis (eg, carrier testing), includes SMN2 (survival of motor neuron 2, centromeric) analysis, if performed
Status Code	Statutory Exclusion (from MPFS, may be paid under other methodologies)
Global Days	XXX - Global Concept Does Not Apply
PC/TC Indicator (26, TC)	9 - Not Applicable
Multiple Procedures (51)	9 - Concept does not apply.
Bilateral Surgery (50)	9 - Concept does not apply.
Physician Supervisions	09 - Concept does not apply.
Assistant Surgeon (80, 82)	9 - Concept does not apply.
Co-Surgeons (62)	9 - Concept does not apply.
Team Surgery (66)	9 - Concept does not apply.
Diagnostic Imaging Family	99 - Concept Does Not Apply
CLIA Waived (QW)	No
APC Status Indicator	Service Paid under Fee Schedule or Payment System other than OPPS
Type of Service (TOS)	5 - Diagnostic Laboratory
Berenson-Eggers TOS (BETOS)	none
MUE	1

90	Reference (outside) laboratory: when laboratory procedures are performed by a party other than the treating or reporting physician or other qualified health care professional, the procedure may be identified by adding modifier 90 to the usual procedure number.
GA	Waiver of liability statement issued as required by payer policy, individual case
59	Distinct procedural service: under certain circumstances, it may be necessary to indicate that a procedure or service was distinct or independent from other non-e/m services performed on the same day. modifier 59 is used to identify procedures/services, other than e/m services, that are not normally reported together, but are appropriate under the circumstances. documentation must support a different session, different procedure or surgery, different site or organ system, separate incision/excision, separate lesion, or separate injury (or area of injury in extensive injuries) not ordinarily encountered or performed on the same day by the same individual. however, when another already established modifier is appropriate it should be used rather than modifier 59. only if no more descriptive modifier is available, and the use of modifier 59 best explains the circumstances, should modifier 59 be used. note: modifier 59 should not be appended to an e/m service. to report a separate and distinct e/m service with a non-e/m service performed on the same date, see modifier 25.
GW	Service not related to the hospice patient's terminal condition
GY	Item or service statutorily excluded, does not meet the definition of any medicare benefit or, for non-medicare insurers, is not a contract benefit
GZ	Item or service expected to be denied as not reasonable and necessary
XS	Separate structure, a service that is distinct because it was performed on a separate organ/structure
XU	Unusual non-overlapping service, the use of a service that is distinct because it does not overlap usual components of the main service