HLA-B27 and modified bone formation.

Of the many associations between histocompatibility antigens and human diseases a prominent one is that between HLA-B27 and inflammatory arthropathies. Hypotheses to explain this association include the B27 gene being linked to a specific immune-response gene required for disease expression and the B27 antigen acting via molecular mimicry with a microorganism or as a microorganism receptor. Alternatively, the HLA-B27 gene might be closely related to a gene which influences bone formation. The finding of a significant association between B27 and Forestier's disease, a disease characterised by abundant new bone formation, supports such a hypothesis.