What are the benefits of sending HLA B27 genotype over HLA B27 antigen when evaluating for spondyloarthritis?  

HLA-B27 is strongly associated with ankylosing spondylitis (AS) which is an inflammatory rheumatic disease that affects the spine, the sacroilliac joints, and peripheral joints. It is also associated with other diseases like acute anterior uveitis, inflammatory bowel disease, or psoriasis. HLA-B27 ...

Agree with Dr. @Marina Magrey. In addition to diagnostic value, it has a prognostic value. In recent onset, axial SpA patients HLA-B27 positivity is associated with more inflammation of SIJ MRI, spinal inflammation, radiographic evidence of disease (and perhaps, shorter duration for radiographic pro...