CPT® Code 81190

Official Description

CSTB (cystatin B) (eg, Unverricht-Lundborg disease) gene analysis; known familial variant(s)

Common Language Description

The CPT® Code 81190 pertains to the molecular genetic testing of the CSTB (cystatin B) gene, specifically focusing on known familial variants associated with Unverricht-Lundborg disease. This condition is a progressive myoclonic epilepsy characterized by involuntary muscle jerking or twitching, which typically manifests between the ages of 6 and 15. The CSTB gene, located on the long arm of chromosome 21 at position 22.3 (21q22.3), encodes the cystatin B protein, which plays a crucial role in regulating cathepsin enzyme activity within cell lysosomes. The gene features a distinctive DNA allele with a dodecamer repeat pattern consisting of 12 amino acids, specifically CCCCG-CCCCG-CG, which usually repeats 2 to 3 times. In individuals diagnosed with Unverricht-Lundborg disease, it is common to find more than 30 dodecamer repeats in both copies of the CSTB gene. However, some patients may present with one gene exhibiting an expanded allele while the other carries one of nine identified mutations, such as amino acid substitutions or a truncated protein that is dysfunctional. The symptoms of this disease can progress to include ataxia, tremors, dysarthria, and cognitive decline, with myoclonus potentially evolving into tonic-clonic seizures, which may be managed with medication. The analysis performed under this code is critical for identifying at-risk family members by examining specific sites on the CSTB gene for mutations that have already been documented in other family members.

1. Indications

The CPT® Code 81190 is indicated for use in the context of familial testing for Unverricht-Lundborg disease, particularly when there is a known family history of the condition. The following indications apply:

Family History of Unverricht-Lundborg Disease Testing is warranted when there is a documented case of Unverricht-Lundborg disease in a family member, allowing for the identification of at-risk relatives.
Known Familial Variants The procedure is specifically designed to analyze the CSTB gene for mutations that have already been identified in affected family members, facilitating targeted genetic counseling and risk assessment.

2. Procedure

The procedure for CPT® Code 81190 involves several key steps to ensure accurate analysis of the CSTB gene for known familial variants. Each step is critical for the successful identification of genetic mutations associated with Unverricht-Lundborg disease.

Step 1: Sample Collection A biological sample, typically blood or saliva, is collected from the individual being tested. This sample serves as the source of DNA for the genetic analysis.
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 is subjected to a targeted analysis of the CSTB gene, focusing on specific exon sequences where known familial variants may exist. This step utilizes techniques such as polymerase chain reaction (PCR) to amplify the relevant gene segments.
Step 4: Mutation Detection The amplified DNA is then analyzed to detect the presence of known mutations. This may involve sequencing the targeted regions or employing other molecular techniques to identify specific genetic alterations.
Step 5: Interpretation of Results The results of the genetic analysis are interpreted in the context of the family history and known variants. This interpretation is crucial for determining the risk of Unverricht-Lundborg disease in at-risk family members.

3. Post-Procedure

After the completion of the genetic testing associated with CPT® Code 81190, several post-procedure considerations are important. The results of the analysis will be communicated to the patient and their family, often accompanied by genetic counseling to discuss the implications of the findings. If a known familial variant is identified, at-risk family members may be advised to undergo testing to determine their genetic status. Additionally, the healthcare provider may recommend follow-up evaluations or monitoring for symptoms associated with Unverricht-Lundborg disease, especially for those who test positive for the familial variant. It is essential to provide support and resources for affected individuals and their families, as the emotional and psychological impact of genetic testing can be significant.

Short Descr	CSTB GENE KNOWN FAMIL VRNT
Medium Descr	CSTB GENE ANALYSIS KNOWN FAMILIAL VARIANTS
Long Descr	CSTB (cystatin B) (eg, Unverricht-Lundborg disease) gene analysis; known familial variant(s)
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