Question: What is the significance of HLA B27 in rheumatic disease?
Answer: HLA B27 is an inherited gene marker associated with a number of related rheumatic diseases. They share in common, features such as spinal and peripheral arthritis, skin and GI disorders, anterior chamber eye disease, and psoriasis like skin lesions. This gene is found with highest prevalence in patients with ankylosing spondylosis (>90%), reactive arthritis (80%), and patients with the combination of peripheral arthritis and either psoriasis or inflammatory bowel disease (50%). Statistics are, however, sometimes misleading. Although it is true that patients with classic disease will show the presence of the HLA B27 gene between 50 and 90+% of the time, if you randomly take 100 persons with the gene marker, you may find evidence of disease in only 25% of the study group. This suggests that most patients with the gene never develop any clinical rheumatic symptoms of significance. (Answer provided by the late Dr. Raymond Federman, aka Dr. Bones, who passed away on September 2, 2003. The care of his patients even in retirement was always his joy.)
