A question often asked by many people with ankylosing spondylitis, especially unmarried and infertile men, is: Is this disease hereditary? Here’s the bad news and the not-so-bad news. Perhaps telling you the bad news first will give you more courage and hope to read on. The bad news is that 90% of people with ankylosing spondylitis are genetically predisposed to the disease, and in 1964 Kell-gren found in a survey of families with ankylosing spondylitis that the average prevalence of the disease was 4% among family members, compared to a national average of 0.1%, a 40-fold difference in prevalence, suggesting that family heritability is indeed associated with the development of ankylosing spondylitis. In 1973, Brewerton et al. obtained evidence of a significant genetic component in the histotyping of patients with ankylosing spondylitis, finding HLA-B27 positivity in 72 of 75 typical patients (96%) and in 31 of their 60 first-degree relatives (51%), whereas in 75 controls, only 3 were positive for HLA-B27 (4 percent, indicating that HLA-B27-positive individuals are closely associated with the development of ankylosing spondylitis. Since the HLA system, like blood group antigens, is genetically determined, heredity is an important factor in the development of ankylosing spondylitis. The not-so-bad news is that only individuals in families with ankylosing spondylitis become ankylosing spondylitis patients, and most people remain free of the disease for life. If you are a patient with ankylosing spondylitis, your child is only 20 to 30 percent likely to develop the disease. In some patients with ankylosing spondylitis, not all of their children are positive for the HLA-B27 antigen, and even if their children are positive, they do not necessarily have the disease because about 5% of normal people can be positive for the HLA-B2 antigen. Patients with ankylosing spondylitis are found to have varying degrees of immunoglobulin, Cf-reactive protein, C , C in immunological tests, which indicates that ankylosing spondylitis is related to autoimmune function, so ankylosing spondylitis, a multidisciplinary disease, is an orthopedic disease with hereditary immunity, in the treatment of autoimmune regulation.