CPT® Code 81186

Official Description

CACNA1A (calcium voltage-gated channel subunit alpha1 A) (eg, spinocerebellar ataxia) gene analysis; known familial variant

Common Language Description

The CPT® Code 81186 pertains to the molecular genetic testing of the CACNA1A gene, specifically focusing on the analysis of known familial variants associated with spinocerebellar ataxia type 6 (SCA6). This genetic condition is characterized by a gradual degeneration of the cerebellum and spinal cord, leading to a range of neurological symptoms. The CACNA1A gene, located on the short arm of chromosome 19 at position 13.13 (19p13.13), encodes a subunit of calcium voltage-gated channels, which are essential for the transport of calcium ions across cell membranes. These channels play a critical role in neuronal communication and neurotransmitter release. The gene contains a specific region that features a trinucleotide repeat sequence of CAG (cytosine-adenine-guanine), which typically repeats between 4 to 18 times in healthy individuals. However, in individuals with SCA6, this repeat can expand to between 20 to 33 times, with the number of repeats correlating with the age of onset and severity of symptoms. Symptoms of SCA6 may include uncoordinated gait (ataxia), dystonia, tremors, loss of coordination in the arms, speech difficulties (dysarthria), involuntary eye movements (nystagmus), and double vision. The analysis performed under CPT® Code 81186 is crucial for identifying these known familial variants, which can help in assessing the risk for family members who may inherit the condition. This testing is part of a broader genetic evaluation process that may also include other codes such as 81184, which detects abnormal alleles, and 81185, which involves a full sequence analysis to identify functional variants. Overall, the use of CPT® Code 81186 is essential for understanding the genetic underpinnings of SCA6 and for guiding clinical management and family planning for affected individuals.

1. Indications

The molecular genetic testing represented by CPT® Code 81186 is indicated for individuals who are suspected of having spinocerebellar ataxia type 6 (SCA6) due to a family history of the condition or the presence of clinical symptoms associated with the disorder. The following conditions and symptoms may warrant this genetic analysis:

Family History of SCA6 Individuals with a known familial variant of the CACNA1A gene, particularly those with relatives diagnosed with SCA6, may be tested to determine their risk of developing the condition.
Neurological Symptoms Patients exhibiting symptoms such as uncoordinated gait (ataxia), dystonia, tremors, loss of arm coordination, dysarthria (difficulty speaking), nystagmus (involuntary eye movements), and double vision may be candidates for this genetic testing to confirm a diagnosis.

2. Procedure

The procedure for CPT® Code 81186 involves several key steps to ensure accurate analysis of the CACNA1A gene for known familial variants. The following procedural steps are typically followed:

Step 1: Sample Collection A biological sample, usually blood or saliva, is collected from the patient. This sample contains DNA, which will be analyzed for mutations in the CACNA1A gene.
Step 2: DNA Extraction The DNA is extracted from the collected sample using standard laboratory techniques. This process isolates the genetic material necessary for further analysis.
Step 3: Targeted Gene Analysis The extracted DNA undergoes targeted analysis focusing on specific exon sequences of the CACNA1A gene. This step is crucial for identifying known familial variants that may be present in the patient's genetic makeup.
Step 4: Variant Identification The laboratory compares the patient's genetic sequence to reference sequences to identify any known familial variants. This comparison helps determine if the patient carries mutations associated with SCA6.
Step 5: Reporting Results Once the analysis is complete, the results are compiled into a report that details the findings, including the presence or absence of known familial variants. This report is then provided to the healthcare provider for further interpretation and clinical decision-making.

3. Post-Procedure

After the completion of the genetic testing under CPT® Code 81186, patients may receive counseling regarding the results, especially if a known familial variant is identified. This counseling can include discussions about the implications for the patient’s health, potential symptoms, and the risk of transmission to family members. Additionally, healthcare providers may recommend follow-up evaluations or monitoring based on the test results. It is important for patients to understand the significance of their genetic findings and how they may impact their health and that of their relatives.

Short Descr	CACNA1A GEN KNOWN FAMIL VRNT
Medium Descr	CACNA1A GENE ANALYSIS KNOWN FAMILIAL VARIANT
Long Descr	CACNA1A (calcium voltage-gated channel subunit alpha1 A) (eg, spinocerebellar ataxia) gene analysis; known familial variant
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