Ankylosing spondylitis (AS) is a seronegative polyarthritis, also known as deformational spondylitis, atrophic spondylitis, ligamentous atrophic spondylitis, and dendritic spondylosis, etc. It is a chronic progressive, independent systemic disease. It mainly affects sacroiliac joints, hip joints, intervertebral joints and costal vertebral joints, with early manifestations of back pain and back ankylosis, and finally disability due to spinal ankylosis. Occasionally, it may cause small joint lesions in the limbs. It is a rheumatic disease with the highest rate of human histocompatibility antigen B27 (HLA-B27) positivity (95% positivity) seronegative, and the rate of HLA-B27 positivity in family members is also 30 times higher than that in normal controls, and the disease can occur in about 60% of members. According to domestic and international reports, there is a tendency of familial development of this disease, and brothers have been found to develop ankylosing spondylitis successively. This suggests that genetic factors play a decisive role in the development of the disease, but the mode of inheritance is still unclear.