VEGF was found to be increased in HA patients with early joint disease, but other studies obtained contrasting results; SDF-1a and MMP-9 were also investigated and found to be increased in HA patient with joint disease; a correlation between VCAM-1 and severe arthropathy at X-ray was identified in a study and other ones found an association of CRP and MIF with acute joint bleeding in HA patients. This evidence concerns the gene VEGFA and arthropathy.