MMP9 and complex regional pain syndrome: Fold changes in the expression of HLA-A29.1, MMP9, ANPEP, HDC, G-CSF3R, and STAT3 genes in the CRPS II subgroup (2.2±0.51, 6.4±2.47, 1.6±0.22, 1.9±0.48, 3.6±0.89, and 1.6±0.16 times, respectively) were higher than for the CRPS (1.9±0.26, 4.0±1.23, 1.4±0.14, 1.8±0.27, 2.3±0.48, and 1.4±0.12 times, respectively) compared to the control.