Additional Information

Testing forwarded to ARUP Laboratory by Warde Medical Laboratory.

ARUP mnemonic is HLAB27 PCR.

May assist in the diagnosis of ankylosing spondylitis. This test is not diagnostic for ankylosing spondylitis and is only suggestive of the condition if there are other clinical signs and symptoms. Test should not be performed for prenatal diagnosis of ankylosing spondylitis since a positive result is not predictive for the disorder.

Background Information for Ankylosing Spondylitis (HLA-B27) Genotyping:

Characteristics: Ankylosing spondylitis (AS) is a chronic inflammatory disease that primarily causes pain and inflammation of the joints between the vertebrae of the spine and the sacroiliac joints. Inflammation and pain may occur in other parts of the body as well. HLA-B27 is strongly associated with ankylosing spondylitis (AS) as well as with Reiter syndrome, anterior uveitis, psoriatic arthritis, and inflammatory bowel disease.

Incidence: Greater than 90 percent of patients with AS are HLA-B27 positive compared to 5-10 percent of the general population.

Penetrance: Two to eight percent of individuals with HLA-B27 will develop AS.

Methodology: Polymerase chain reaction (PCR) and fluorescent hybridization probes.

Analytical Sensitivity & Specificity: 99 percent

Limitations: Rare alleles present in less than 1 percent of most populations will not be detected. Diagnostic errors can occur due to rare sequence variations.