MHC-HLA B27

SUMMARY

Major Histocompatibility Complex (MHC) found in:
1. Reactive arthritis: 60-80%, higher when sacroiliitis is present
2. Ankylosing spondylitis (AS): 90%
3. Psoriatic arthritis: up to 60% (particularly with spinal/axial disease)
4. Inflammatory bowel disease (IBD) with associated axial joint arthritis: up to 60%

NOTE: this test has limited clinical usefulness if not ordered in the right clinical scenario. A negative HLA-B27 test is useful in ruling out ankylosing spondylitis.

Reference(s)

Wilkinson, I., Furmedge, D. and Sinharay, R. (2017). Oxford handbook of clinical medicine. Oxford: Oxford University Press. Get it on Amazon.
Feather, A., Randall, D. and Waterhouse, M. (2020). Kumar And Clark’s Clinical Medicine. 10th ed. S.L.: Elsevier Health Sciences. Get it on Amazon.
Hannaman, R. A., Bullock, L., Hatchell, C. A., & Yoffe, M. (2016). Internal medicine review core curriculum, 2017-2018. CO Springs, CO: MedStudy.
Therapeutic Guidelines. Melbourne: Therapeutic Guidelines Limited. https://www.tg.org.au [Accessed 2021].