CPT® Code 81187

Official Description

CNBP (CCHC-type zinc finger nucleic acid binding protein) (eg, myotonic dystrophy type 2) gene analysis, evaluation to detect abnormal (eg, expanded) alleles

Common Language Description

The CPT® Code 81187 pertains to the molecular genetic testing of the CNBP (CCHC-type zinc finger nucleic acid binding protein) gene, specifically aimed at identifying mutations associated with myotonic dystrophy type 2. This gene is located on the long (q) arm of chromosome 3 at position 21.3 (3q21.3) and is crucial for producing the CCHC-type zinc finger nucleic acid binding protein, which is predominantly found in heart and skeletal muscle tissues. The CNBP protein features seven zinc finger domains that play a vital role in binding to specific DNA and RNA sites, thereby regulating gene activity. In individuals with myotonic dystrophy type 2, a particular region of the CNBP gene exhibits a tetranucleotide repeat pattern of the sequence CCTG, which typically occurs fewer than 26 times in healthy individuals. However, in affected individuals, this repeat can expand to a minimum of 75 and, in some cases, can reach up to 11,000 repeats. This abnormal expansion leads to the production of an altered form of messenger RNA, resulting in the aggregation of protein molecules within muscle cells, which disrupts normal muscle function. Symptoms of myotonic dystrophy type 2 generally manifest in adulthood and can vary significantly in severity. Common symptoms include progressive muscle wasting and weakness, prolonged muscle contractions (myotonia), cataracts, cardiac arrhythmias, as well as early balding and infertility in males. The code 81187 is utilized to report the analysis of the CNBP gene for the evaluation of these expanded alleles.

1. Indications

The CNBP gene analysis is indicated for the evaluation of individuals suspected of having myotonic dystrophy type 2. This testing is particularly relevant for patients presenting with symptoms such as:

Progressive Muscle Wasting and Weakness - A gradual loss of muscle mass and strength that can affect daily activities.
Prolonged Muscle Contraction (Myotonia) - Difficulty in relaxing muscles after contraction, leading to stiffness and discomfort.
Cataracts - The development of clouding in the lens of the eye, which can impair vision.
Cardiac Arrhythmias - Irregular heartbeats that can lead to various cardiovascular complications.
Early Balding and Infertility in Males - These symptoms may also be present, indicating a potential genetic condition.

2. Procedure

The procedure for CNBP gene analysis involves several key steps to ensure accurate detection of abnormal alleles. First, a sample is collected from the patient, typically through a blood draw or saliva sample, which contains the necessary genetic material for analysis. Next, the laboratory performs DNA extraction to isolate the genetic material from the sample. Following extraction, polymerase chain reaction (PCR) techniques are employed to amplify the specific region of the CNBP gene that contains the tetranucleotide repeat sequence. This amplification is crucial for detecting any expansions in the repeat number. Once amplification is complete, the laboratory utilizes various methods, such as gel electrophoresis or sequencing, to analyze the amplified DNA. These techniques allow for the visualization and quantification of the repeat number, enabling the identification of expanded alleles characteristic of myotonic dystrophy type 2. The results of the analysis are then compiled into a report, which details the findings and indicates whether abnormal alleles were detected. This comprehensive approach ensures that the testing is thorough and reliable, providing essential information for diagnosis and management of the condition.

3. Post-Procedure

After the CNBP gene analysis is completed, the results are typically reviewed by a healthcare professional, who will discuss the findings with the patient. If expanded alleles are detected, further counseling may be provided regarding the implications of the results, including potential management strategies for myotonic dystrophy type 2. Patients may also be advised on monitoring for associated symptoms and conditions, such as cardiac issues or cataracts. Additionally, genetic counseling may be recommended for family members, as myotonic dystrophy type 2 is an inherited condition. Overall, the post-procedure phase focuses on ensuring that patients understand their results and the next steps in their care plan.

Short Descr	CNBP GENE DETC ABNOR ALLELE
Medium Descr	CNBP GENE ANALYSIS EVAL DETECT ABNORMAL ALLELES
Long Descr	CNBP (CCHC-type zinc finger nucleic acid binding protein) (eg, myotonic dystrophy type 2) gene analysis, evaluation to detect abnormal (eg, expanded) alleles
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

GA	Waiver of liability statement issued as required by payer policy, individual case
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.