CPT® Code 81177

Official Description

ATN1 (atrophin 1) (eg, dentatorubral-pallidoluysian atrophy) gene analysis, evaluation to detect abnormal (eg, expanded) alleles

Common Language Description

The CPT® Code 81177 pertains to the molecular genetic testing specifically aimed at analyzing the ATN1 (atrophin 1) gene, which is associated with a condition known as dentatorubral-pallidoluysian atrophy (DRPLA). This gene is located on the short (p) arm of chromosome 12 at the position designated as 12p13.31. The primary function of the ATN1 gene is to provide the necessary instructions for the synthesis of the atrophin 1 protein. In individuals affected by DRPLA, there is an abnormal accumulation of this altered atrophin 1 protein within the brain, leading to the destruction of neurons and the subsequent development of the disease. The normal function of the ATN1 gene includes maintaining a specific range of trinucleotide CAG (cytosine-adenine-guanine) repeats, which typically ranges from 6 to about 35. However, in cases of DRPLA, the number of CAG repeats is significantly higher, often reaching 48 or more. This genetic mutation primarily affects individuals of Asian descent, with symptoms that can manifest at any age between 1 and 72 years, although the average age of onset is around 31 years. In children, the symptoms of DRPLA may include progressive ataxia, myoclonus, seizures, and intellectual deterioration. Adults may experience a different set of symptoms, including ataxia, choreoathetosis, dementia, and changes in personality. Management of these symptoms can involve the use of antiepileptic medications for seizure control, psychotropic drugs to address personality changes, and physical rehabilitation to assist with ataxia, myoclonus, and choreoathetosis. The code 81177 is specifically utilized to report the analysis of the ATN1 gene for the purpose of evaluating and detecting these abnormal (expanded) alleles associated with DRPLA.

1. Indications

The molecular genetic testing represented by CPT® Code 81177 is indicated for the evaluation of individuals suspected of having dentatorubral-pallidoluysian atrophy (DRPLA). The following conditions and symptoms may warrant this genetic analysis:

Progressive Ataxia - A condition characterized by a gradual loss of coordination and balance, which may be observed in both children and adults.
Myoclonus - Involuntary muscle jerks or spasms that can occur in affected individuals, particularly in children.
Seizures - Episodes of uncontrolled electrical activity in the brain, which may be present in pediatric patients.
Intellectual Deterioration - A decline in cognitive function that can manifest in children diagnosed with DRPLA.
Choreoathetosis - A movement disorder characterized by irregular, unintentional movements, typically seen in adult patients.
Dementia - A decline in mental ability severe enough to interfere with daily life, which may develop in adults with DRPLA.
Personality Changes - Alterations in behavior and personality that can occur in adult patients as the disease progresses.

2. Procedure

The procedure for conducting the ATN1 gene analysis involves several key steps to ensure accurate detection of abnormal alleles associated with dentatorubral-pallidoluysian atrophy (DRPLA). 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 serves as the source of DNA for the genetic analysis.
Step 2: DNA Extraction - The DNA is extracted from the collected sample using standardized laboratory techniques. This process isolates the genetic material necessary for testing.
Step 3: PCR Amplification - Polymerase chain reaction (PCR) is employed to amplify the specific regions of the ATN1 gene that contain the CAG repeat sequences. This step is crucial for ensuring that there is enough DNA for accurate analysis.
Step 4: Genetic Analysis - The amplified DNA is analyzed to determine the number of CAG repeats present in the ATN1 gene. This analysis may involve sequencing or other molecular techniques to identify any expansions indicative of DRPLA.
Step 5: Interpretation of Results - The results of the genetic analysis are interpreted by a qualified geneticist or laboratory professional. They will assess whether the number of CAG repeats falls within the normal range or indicates an abnormal expansion associated with DRPLA.
Step 6: Reporting - A comprehensive report is generated, detailing the findings of the genetic analysis, including the number of CAG repeats and any identified mutations. This report is then provided to the referring physician for further clinical decision-making.

3. Post-Procedure

After the ATN1 gene analysis is completed, the patient may receive counseling regarding the results, especially if an abnormal allele is detected. This counseling can help the patient and their family understand the implications of the findings, including potential symptoms and management strategies for dentatorubral-pallidoluysian atrophy (DRPLA). Follow-up appointments may be scheduled to discuss the results in detail and to plan any necessary interventions or supportive care. Additionally, genetic counseling may be recommended for family members, as DRPLA can have hereditary implications. It is important for healthcare providers to ensure that patients are informed about the nature of the condition, available treatment options, and resources for support.

Short Descr	ATN1 GENE DETC ABNOR ALLELES
Medium Descr	ATN1 GENE ANALYSIS EVAL DETECT ABNORMAL ALLELES
Long Descr	ATN1 (atrophin 1) (eg, dentatorubral-pallidoluysian atrophy) 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

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
GW	Service not related to the hospice patient's terminal condition
XS	Separate structure, a service that is distinct because it was performed on a separate organ/structure