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Test Code SBULB Spinobulbar Muscular Atrophy (Kennedy Disease), Molecular Analysis, Varies

Reporting Name

Spinobulbar Musc Atrophy, Kennedy's

Performing Laboratory

Mayo Clinic Laboratories in Rochester

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

Method Name

A Polymerase Chain Reaction (PCR)-based assay is utilized to detect expansion-type mutations (CAG repeats) within the androgen receptor gene.

Shipping Instructions

Specimen preferred to arrive within 96 hours of draw.

Specimen Required

Patient Preparation: A previous bone marrow transplant from an allogenic donor will interfere with testing. Call 800-533-1710 for instructions for testing patients who have received a bone marrow transplant.

Specimen Type: Whole blood


Preferred: Lavender top (EDTA) or yellow top (ACD)

Acceptable: Any anticoagulant

Specimen Volume: 3 mL

Collection Instructions:

1. Invert several times to mix blood.

2. Send specimen in original tube.

Specimen Type


Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Varies Ambient (preferred)

Reject Due To

All specimens will be evaluated by Mayo Clinic Laboratories for test suitability.

Reference Values

Normal alleles: 11-34 CAG repeats

Abnormal alleles: 36-62 CAG repeats


An interpretive report will be provided.


An interpretive report will be provided.

Day(s) and Time(s) Performed

Tuesday; 10 a.m.

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

CPT Code Information

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

LOINC Code Information

Test ID Test Order Name Order LOINC Value
SBULB Spinobulbar Musc Atrophy, Kennedy's In Process


Result ID Test Result Name Result LOINC Value
53341 Result Summary 50397-9
53342 Result 82939-0
53343 Interpretation 69047-9
53344 Reason for Referral 42349-1
53345 Specimen 31208-2
53346 Source 31208-2
53348 Released By 18771-6


1. New York Clients-Informed consent is required. Document on the request form or electronic order that a copy is on file. The following documents are available in Special Instructions:

-Informed Consent for Genetic Testing (T576)

-Informed Consent for Genetic Testing-Spanish (T826)

2. Molecular Genetics: Neurology Patient Information in Special Instructions

3. If not ordering electronically, complete, print, and send a Neurology Specialty Testing Client Test Request (T732) with the specimen.

Testing Algorithm

See Inherited Motor Neuron Disease Testing Algorithm in Special Instructions.