Ordering Recommendation

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.

New York DOH Approval Status

This test is New York state approved.

Specimen Required

Patient Preparation

Lavender (EDTA), pink (K2EDTA), or yellow (ACD solution A or B).

Specimen Preparation

Transport 3 mL whole blood. (Min: 1 mL)

Storage/Transport Temperature


Unacceptable Conditions

Plasma or serum; collection of specimen in sodium heparin tubes. Frozen specimens in glass collection tubes.


Ambient: 72 hours; Refrigerated: 1 week; Frozen: 1 month


Polymerase Chain Reaction (PCR)/Fluorescence Monitoring




3-7 days

Reference Interval

By report

Interpretive Data

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 fluorescence monitoring.
Analytical Sensitivity and Specificity: 99 percent
Limitations: This test does not rule out the B*27:06 and 27:09 alleles, which are not associated with spondyloarthropathies. Certain rare alleles present in less than 1 percent of the population will not be detected. Other rare, or uncharachterized alleles may occur which may lead to false positive or false negative results.

Counseling and informed consent are recommended for genetic testing. Consent forms are available online.

Compliance Category

Laboratory Developed Test (LDT)


Hotline History


CPT Codes



Component Test Code* Component Chart Name LOINC
0050406 Ankylosing Spondylitis (HLAB27) 26043-0
2001317 Ankylosing Spondylitis (HLAB27) Specimen 31208-2
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.


  • HLA B27 genotyping
  • HLA-B27
Ankylosing Spondylitis (HLA-B27) Genotyping