Which genetic marker is associated with reactive arthritis?

Reactive arthritis is a type of inflammatory arthritis that occurs as a reaction to an infection in another part of the body, typically after genitourinary or gastrointestinal infections. It is commonly associated with the HLA-B27 genetic marker. HLA-B27 is part of the major histocompatibility complex (MHC) class I molecules and has been shown to be strongly associated with several autoimmune conditions, including ankylosing spondylitis and reactive arthritis.

The association with HLA-B27 is thought to contribute to a hyperreactive immune response to certain infections, particularly those caused by organisms such as Chlamydia, Shigella, or Yersinia. Studies have shown that a significant percentage of patients with reactive arthritis express this antigen, which helps to identify individuals at risk for developing the condition.

In contrast, other markers such as HLA-DR4, HLA-B5, and HLA-DQ2 have different associations with various other conditions, such as rheumatoid arthritis or celiac disease, but they do not have the same established link to reactive arthritis as HLA-B27 does. Understanding the specific genetic markers associated with diseases helps in diagnosis and guiding treatment strategies.