HTT (huntingtin) (eg, Huntington disease) gene analysis; evaluation to detect abnormal (eg, expanded) alleles
CPT4 code
Name of the Procedure:
HTT (Huntingtin) Gene Analysis; Evaluation to Detect Abnormal (Expanded) Alleles
Common Name: Huntington's Disease Genetic Test
Technical Term: HTT Gene Analysis
Summary
The HTT gene analysis is a genetic test used to determine if an individual has an abnormal (expanded) allele in the huntingtin gene. This is associated with Huntington's disease, a hereditary condition that causes the progressive breakdown of nerve cells in the brain.
Purpose
The procedure addresses Huntington's disease, a neurodegenerative disorder. The goal is to detect the presence of abnormal alleles in the HTT gene, which indicates an increased risk or presence of Huntington's disease. This information can assist in confirming a diagnosis, predicting disease onset, and providing information for family planning.
Indications
- Family history of Huntington's disease.
- Symptoms such as involuntary movements, cognitive decline, and psychiatric issues.
- Individuals with a parent diagnosed with Huntington's disease.
- Prenatal testing when one parent carries the abnormal HTT gene.
Preparation
- No special diet or fasting required.
- Patients should provide a detailed family medical history.
- Genetic counseling is recommended before and after the test.
Procedure Description
- A sample of blood or saliva is collected from the patient.
- The sample is sent to a laboratory for DNA extraction.
- Laboratory technicians analyze the DNA to check for the number of CAG repeats in the HTT gene.
- Results are compared to normal and abnormal ranges to determine if expanded alleles are present.
Duration
The sample collection takes about 15-30 minutes. Results typically take several weeks to be processed.
Setting
The procedure is performed in an outpatient clinic, hospital, or genetic testing center.
Personnel
- Nurse or phlebotomist for sample collection.
- Medical laboratory technologist for DNA analysis.
- Genetic counselor and physician for interpreting results and providing guidance.
Risks and Complications
- Possible minor discomfort or bruising at the blood draw site.
- Emotional and psychological impact of test results.
- Low risk of incorrect results due to laboratory error.
Benefits
- Accurate diagnosis or risk assessment for Huntington’s disease.
- Information for making informed family planning decisions.
- Early intervention and management planning.
Recovery
- No physical recovery needed.
- Psychological support may be necessary depending on the outcome.
Alternatives
- Clinical evaluation based on family history and symptoms (may be less definitive).
- No testing, with focus on symptom monitoring (might delay diagnosis and intervention).
Patient Experience
- The blood draw is quick and may cause slight discomfort.
- Anxiety or stress related to awaiting and receiving the results.
- Genetic counseling can provide emotional support and additional information.