Genetic predisposition to two rheumatic diseases

The co-existence of ankylosing spondylitis and rheumatoid arthritis is uncommon and usually occurs in a male with a long history of back pain followed by the appearance of clinical features of ankylosing spondylitis, while features of rheumatoid arthritis develop in the third or fourth decade of life. Recently, histocompatibility (HLA) antigens have partially elucidated the genetic factors predisposing to both diseases. We report a patient with ankylosing spondylitis and rheumatoid arthritis who had the associated HLA genes.