81204 AR (androgen receptor) (eg, spinal and bulbar muscular atrophy, Kennedy disease, X chromosome inactivation) gene analysis; characterization of alleles (eg, expanded size or methylation status)

Name of the Procedure:

Androgen Receptor (AR) Gene Analysis

• Common Name(s): AR Gene Testing
• Medical Terms: Androgen Receptor Gene Analysis, Characterization of Alleles

Summary

AR gene analysis is a genetic test that examines specific characteristics of the androgen receptor gene, including the size of expanded sequences and methylation status. It is often used to diagnose disorders such as spinal and bulbar muscular atrophy (SBMA), also known as Kennedy disease, and to study X chromosome inactivation.

Purpose

This procedure is used to identify genetic mutations that cause neurological and muscular conditions like SBMA/Kennedy disease. The primary goal is to confirm the diagnosis, which can help in managing the patient's condition and providing information on prognosis and potential treatment options.

Indications

• Symptoms of SBMA/Kennedy disease, such as muscle weakness, cramps, and twitching.
• Symptoms of X-linked disorders affecting androgen receptor function.
• Family history of SBMA or other androgen receptor-related conditions.

Preparation

• No special preparation is usually required.
• Pre-procedure genetic counseling may be recommended.
• Collection of a blood sample or buccal swab may be required.

Procedure Description

1. A blood sample or cheek swab is collected from the patient.
2. DNA is extracted from the sample in a laboratory.
3. The AR gene is analyzed to characterize specific alleles, focusing on expanded CAG repeats and methylation status.
4. Advanced techniques like polymerase chain reaction (PCR) and sequencing are used to assess the genetic material.

Duration

• Sample collection: Approximately 10-15 minutes.
• Laboratory analysis: Several days to a few weeks, depending on the complexity.

Setting

• Sample collection typically occurs in a hospital, outpatient clinic, or genetic testing center.
• The laboratory analysis takes place in a specialized genetic testing laboratory.

Personnel

• Geneticist or genetic counselor
• Phlebotomist or medical technician for sample collection
• Laboratory technicians specialized in genetic testing

Risks and Complications

• Minimal risks associated with blood sample collection, such as slight pain, bruising, or infection at the puncture site.
• No significant risks with buccal swab collection.

Benefits

• Accurate diagnosis of conditions like SBMA/Kennedy disease.
• Useful information for genetic counseling and family planning.
• Insight into the prognosis and potential treatment strategies.

Recovery

• No recovery time is needed for the sample collection.
• Patients can resume normal activities immediately after the sample is collected.
• Follow-up appointments may be necessary to discuss results.

Alternatives

• Electromyography (EMG) and nerve conduction studies for symptomatic evaluation.
• Muscle biopsy for differential diagnosis.
• These alternatives are less definitive for confirming specific genetic mutations.

Patient Experience

• Blood sample collection may involve a brief needle prick.
• Buccal swab collection is quick and non-invasive.
• Patients may feel anxious waiting for results, and genetic counseling can provide support and information.