HLA-B27
Pronunciation: H-L-A B twenty-seven
Also written as: HLA-B27 — Human Leukocyte Antigen B27
A genetic marker strongly associated with spondyloarthropathies and enthesitis-related arthritis in pediatric patients.
Full Definition
HLA-B27 (Human Leukocyte Antigen B27) is a cell surface protein encoded by the HLA-B gene and part of the major histocompatibility complex. In pediatric rheumatology, HLA-B27 testing is particularly relevant for children with suspected enthesitis-related arthritis or spondyloarthropathy. Approximately 80-90% of patients with ankylosing spondylitis carry this marker, compared to only 6-8% of the general population. While HLA-B27 positivity increases the risk of developing spondyloarthropathy, the majority of HLA-B27-positive individuals never develop disease. In children, positive testing may influence treatment decisions and family counseling regarding future disease risk.
Usage
Usage note: Always include hyphen between HLA and B27; specify positive or negative result when documenting.
In Context
- "HLA-B27 testing was positive in this patient with enthesitis-related arthritis and sacroiliitis." — Laboratory result
- "The family history of HLA-B27-positive ankylosing spondylitis guided genetic counseling for this patient." — Genetic counseling note