Not a diagnostic test for ankylosing spondylitis. May assist in the diagnosis of the condition only if other clinical signs and symptoms are present. Test should not be performed for prenatal diagnosis of ankylosing spondylitis because a positive result is not predictive for the disorder.
- Patient Preparation
- Lavender (EDTA), pink (K2EDTA), or yellow (ACD Solution A or B).
- Specimen Preparation
- Do not freeze. Transport 3 mL whole blood. (Min: 1 mL)
- Storage/Transport Temperature
- Unacceptable Conditions
- Plasma or serum; collection of specimen in sodium heparin tubes.
- Ambient: 72 hours; Refrigerated: 1 week; Frozen: Unacceptable
Positive: The specimen is positive for HLA-B27.
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.
Counseling and informed consent are recommended for genetic testing. Consent forms are available online.
|Component Test Code*||Component Chart Name||LOINC|
|0050406||Ankylosing Spondylitis (HLAB27)||26043-0|
|2001317||Ankylosing Spondylitis (HLAB27) Specimen||31208-2|
- HLA B27 genotyping