Question: HLA-B27 and Rheumatic Disease
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 gastrointestinal disorders, anterior chamber eye disease, and psoriasis-like skin lesions.
The gene is found with highest prevalence in patients with ankylosing spondylitis (greater than 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, a respected rheumatologist.