CPT® Code 81274

Official Description

HTT (huntingtin) (eg, Huntington disease) gene analysis; characterization of alleles (eg, expanded size)

Common Language Description

The CPT® Code 81274 pertains to the molecular genetic testing of the HTT (huntingtin) gene, specifically focusing on the characterization of alleles associated with Huntington disease. Huntington disease is a progressive neurodegenerative disorder that significantly impacts cognitive and motor functions. The HTT gene, located on the short arm of chromosome 4 at position 16.3 (4p16.3), encodes a protein that plays a crucial role in the functioning of nerve cells, which is essential for normal brain development. This gene is involved in various cellular processes, including chemical signaling, protein binding, and cellular protection against self-destruction. The testing performed under this code aims to identify abnormal or expanded alleles of the HTT gene, which are linked to the onset and progression of Huntington disease. The gene features a specific DNA sequence characterized by a trinucleotide repeat pattern of cytosine, adenine, and guanine (CAG), which typically repeats between 10 to 35 times in healthy individuals. However, when this repeat expands beyond the normal range, it can lead to the production of an elongated protein that is prone to fragmentation and accumulation within nerve cells, contributing to the symptoms of the disease. Symptoms of Huntington disease can manifest as cognitive decline, dementia, apathy, depression, anxiety, and involuntary movements, with onset varying from childhood or adolescence in juvenile cases to mid-adulthood in typical cases. The testing provided by CPT® Code 81274 is essential for determining the characteristics of these expanded alleles, including their size and any similarities or differences that may exist among them. This information is critical for understanding the genetic basis of the disease and for assessing the risk of transmission to future generations.

1. Indications

The HTT gene analysis using CPT® Code 81274 is indicated for the following conditions and circumstances:

Huntington Disease Diagnosis Molecular genetic testing is performed to confirm a diagnosis of Huntington disease in individuals exhibiting symptoms such as cognitive impairment, motor dysfunction, and psychiatric symptoms.
Family History of Huntington Disease Testing is indicated for individuals with a family history of Huntington disease to assess their risk of developing the condition based on the presence of expanded alleles.
Pre-symptomatic Testing Individuals at risk for Huntington disease may undergo testing to determine if they carry the expanded CAG repeats associated with the disorder, even before symptoms appear.
Genetic Counseling The analysis is also indicated for individuals seeking genetic counseling regarding the implications of their genetic status for themselves and their family members.

2. Procedure

The procedure for CPT® Code 81274 involves several key steps to ensure accurate characterization of the HTT gene alleles:

Sample Collection A biological sample, typically blood or saliva, is collected from the patient. This sample contains the DNA necessary for genetic analysis.
DNA Extraction The DNA is extracted from the collected sample using standardized laboratory techniques to isolate the genetic material for testing.
Polymerase Chain Reaction (PCR) The extracted DNA undergoes PCR amplification, a process that selectively replicates the specific region of the HTT gene containing the CAG repeat sequence, allowing for detailed analysis.
Allele Characterization The amplified DNA is then analyzed to characterize the alleles, focusing on the number of CAG repeats. This step determines whether the alleles are normal, pre-mutation, or expanded, which is critical for understanding the patient's risk for Huntington disease.
Data Interpretation The results are interpreted by a qualified geneticist or laboratory professional, who assesses the significance of the findings in the context of the patient's clinical presentation and family history.
Reporting Finally, a comprehensive report is generated, detailing the findings of the allele characterization, which is then provided to the referring physician for further clinical decision-making.

3. Post-Procedure

After the HTT gene analysis is completed, patients may receive counseling regarding the results, especially if expanded alleles are identified. This counseling can include discussions about the implications of the findings for the patient’s health, potential symptoms, and the risk of transmission to offspring. Follow-up appointments may be necessary to address any questions or concerns and to discuss potential monitoring or management strategies based on the results of the genetic testing. Additionally, patients may be advised on the importance of family planning and the options available for those who may be at risk for Huntington disease.

Short Descr	HTT GENE CHARAC ALLELES
Medium Descr	HTT GENE ANALYSIS CHARACTERIZATION ALLELES
Long Descr	HTT (huntingtin) (eg, Huntington disease) gene analysis; characterization of alleles (eg, expanded size)
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