Acharya et al. investigated levels of plasma VEGF-A, stromal cell-derived factor 1 alfa (SDF-1α) and matrix metallopeptidase 9 (MMP-9) in hemophilia patients with joint disease versus patients with a bleeding disorder without joint disease and found a significant 4-fold elevation in hemophilia patients [44]. The gene discussed is MMP9; the disease is hemophilia.