Androgen Receptor (AR) Gene Analysis (Kennedy Disease)
Label Mnemonic: SBULB
Epic Lab Code: LAB4077
Downtime Form: A-1a Doctor/Provider Orders - Pathology Core and Specialty Care Nursery
Commercial Mail-out Laboratory
5231 RCP
Whole Blood
Specimen Instructions:
1. Invert several times to mix blood.
2. Send specimen in original tube.
Specimen must arrive within 96 hours of draw.
No holiday blood draws.
Collection Medium:
Lavender top tube 3 mL (EDTA)
Alternate Collection Media:
Yellow top tube 8.5 mL (ACD solution A)
Preferred Minimum: 3 mL whole blood
Absolute Minimum: 1 mL whole blood
Turn Around Time:
5 days upon receipt at reference laboratory
Reference Range:
Normal alleles: 11-34 CAG repeats
Abnormal alleles: 36-62 CAG repeats

An interpretive report will be provided.
Interpretive Data:
An interpretive report will be provided.
Useful For:
Molecular confirmation of clinically suspected cases of sporadic or familial spinobulbar muscular atrophy (SBMA)

Presymptomatic testing for individuals with a family history of SBMA and a documented expansion in the androgen receptor (AR) gene

For predictive testing, it is important to first document the presence of a CAG-repeat amplification in the AR gene in an affected family member to confirm that molecular expansion is the underlying mechanism of disease in the family.

We strongly recommend that patients undergoing predictive testing receive genetic counseling both prior to testing and after results are available.

Predictive testing of an asymptomatic child is not recommended.

Test results should be interpreted in the context of clinical findings, family history, and other laboratory data. Errors in our interpretation of results may occur if information given is inaccurate or incomplete.

A previous bone marrow transplant from an allogenic donor will interfere with testing. Call Commercial Mailout Laboratory (356-3527) for instructions for testing patients who have received a bone marrow transplant.

Current evidence suggests that the majority of individuals with SBMA have a CAG-repeat expansion. However, we cannot eliminate the possibility that another type of mutation not detected by our assay is present within the AR gene.

This mailout test requires pathologist approval for orders during inpatient encounters. Mailouts staff will not process order without approval. The pathologist covering mailouts approval can be reached at pager #5379. If approval is given, the name of the pathologist can be selected in the drop-down menu to the right of the approval warning in Epic when ordering the test.

Please print, complete, and submit the Molecular Genetics: Congenital Inherited Diseases Patient Information Sheet and the Informed Consent for Genetic Testing from Mayo Medical Laboratories with the A-1a Miscellaneous Request.
A polymerase chain reaction (PCR)-based assay is utilized to detect expansion-type mutations (CAG repeats) within the androgen receptor gene.
CPT Code:
81401-AR (androgen receptor) (eg, spinal and bulbar muscular atrophy, Kennedy disease, X chromosome inactivation), characterization of alleles (eg, expanded size or methylation status)