MMP9 and complex regional pain syndrome: Compared to controls, HLA-DRB1, HLA-A29.1, HLA-DRB6, MMP9, PTGS2, IL-8, MMP25, ANPEP, HDC, G-CSF3R, and STAT3 were up-regulated, while ARHGEF10 was down-regulated in CRPS patients (Table 2).