CRP and enthesitis: In the comparison between JAS patients with HLA-B27-positive and HLA-B27-negative, patients with peripheral arthritis and enthesitis in the HLA-B27-negative group were less than those in HLA-B∗2704 group; the inflammatory indicators, such as BASDAI, ESR, and CRP, in patients with HLA-B27-negative were lower than those in patients with HLA-B∗2704, which indicated the milder level of inflammation in HLA-B27-negative patients.