How To Use CPT Code 81329

CPT 81329 is a code used for the analysis of the SMN1 and SMN2 genes, commonly associated with spinal muscular atrophy. This article will cover the description, procedure, qualifying circumstances, usage, documentation requirements, billing guidelines, historical information, similar codes, and examples of CPT code 81329 procedures.

1. What is CPT 81329?

CPT 81329 is a code used to describe the analysis of the survival of motor neuron 1 (SMN1) and survival of motor neuron 2 (SMN2) genes. This test is typically performed to detect deletions in the SMN1 gene and may also analyze the SMN2 gene copy number. The analysis is commonly ordered to aid in the diagnosis of spinal muscular atrophy (SMA) or to determine carrier status.

2. 81329 CPT code description

The official description of CPT code 81329 is: “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.”

3. Procedure

1. Collect a specimen, such as blood, from the patient.
2. Extract the nucleic acids from the specimen using methods such as cell lysis and digestion.
3. Amplify and stabilize the quantity of nucleic acid for analysis using a method such as polymerase chain reaction (PCR).
4. Analyze the SMN1 gene to detect deletions in exon 1.
5. If requested, analyze the SMN2 gene copy number.
6. Report the results of the analysis to the ordering clinician.

4. Qualifying circumstances

Patients who are eligible to receive CPT code 81329 services include those who are suspected of having spinal muscular atrophy (SMA) or those who may be carriers of the condition. This test may also be ordered for individuals with a family history of SMA or those who are planning to have children and want to determine their carrier status.

5. When to use CPT code 81329

It is appropriate to bill the 81329 CPT code when a clinician orders the analysis of the SMN1 and SMN2 genes for the purpose of diagnosing spinal muscular atrophy, determining carrier status, or assessing the risk of having a child with SMA. The test should be performed following the specific procedure outlined in section 3 of this article.

6. Documentation requirements

To support a claim for CPT 81329, the following information should be documented:

• Indication for the test, such as suspected SMA, carrier status determination, or family history of SMA.
• Details of the specimen collection, including the type of specimen and collection method.
• Methods used for nucleic acid extraction, amplification, and analysis.
• Results of the SMN1 and SMN2 gene analysis, including any detected deletions or copy number variations.
• Interpretation of the results by a qualified physician, if applicable.

7. Billing guidelines

When billing for CPT code 81329, it is important to follow the appropriate guidelines and rules. Some payers may pay separately for collecting the specimen using a code such as 36415. If the ordering clinician separately requests physician interpretation of the 81329 test and the pathologist renders an interpretation and writes a report, you can additionally report G0452 with modifier 26 to Medicare and perhaps other payers. An MD or DO physician, not a PhD laboratory scientist, must perform the interpretation according to CMS. Be sure to distinguish the three CPT-listed tests for the SMN1 gene: 81329 for deletion detection, 81336 for full genes sequence analysis, and 81337 for known familial variant(s).

8. Historical information

CPT 81329 was added to the Current Procedural Terminology system on January 1, 2019. There have been no updates to the code since its addition.

9. Similar codes to CPT 81329

Five similar codes to CPT 81329 and how they differentiate from CPT 81329 are:

1. CPT 81336: This code is used for the full gene sequence analysis of the SMN1 gene, rather than just deletion detection.
2. CPT 81337: This code is used for the analysis of known familial variant(s) in the SMN1 gene.
3. CPT 81220: This code is used for the analysis of the CFTR gene, which is associated with cystic fibrosis.
4. CPT 81221: This code is used for the analysis of known familial variant(s) in the CFTR gene.
5. CPT 81222: This code is used for the full gene sequence analysis of the CFTR gene.

10. Examples

Here are 10 detailed examples of CPT code 81329 procedures:

1. A patient with a family history of spinal muscular atrophy undergoes SMN1 and SMN2 gene analysis to determine their carrier status.
2. A couple planning to have children undergoes SMN1 and SMN2 gene analysis to assess their risk of having a child with SMA.
3. A child with symptoms of muscle weakness and loss of motor control undergoes SMN1 and SMN2 gene analysis to aid in the diagnosis of SMA.
4. A patient with a known deletion in the SMN1 gene undergoes SMN2 gene copy number analysis to determine the severity of their SMA symptoms.
5. A pregnant woman with a family history of SMA undergoes SMN1 and SMN2 gene analysis to determine the risk of her unborn child having the condition.
6. A patient with a sibling diagnosed with SMA undergoes SMN1 and SMN2 gene analysis to determine their carrier status and risk of having a child with SMA.
7. A patient with progressive muscle weakness and respiratory issues undergoes SMN1 and SMN2 gene analysis to aid in the diagnosis of SMA.
8. A couple with a child diagnosed with SMA undergoes SMN1 and SMN2 gene analysis to determine their carrier status and risk of having another child with the condition.
9. A patient with a known SMN1 gene deletion undergoes SMN2 gene copy number analysis to assess the potential effectiveness of SMA-targeted therapies.
10. A patient with a family history of SMA and a known SMN1 gene deletion undergoes SMN2 gene copy number analysis to determine the severity of their SMA symptoms and potential response to treatment.