In the case of pigment epithelium‐derived factor (PEDF), circulating levels are increased in patients with PDR, compared to those without, yet in ocular tissue, PEDF levels are lower in patients with late‐stage DR than in those without retinopathy (Jenkins et al., 2007; Li et al., 2012; McAuley et al., 2014). This evidence concerns the gene SERPINF1 and retinal disorder.