Regulated on Activation, Normal T-cell Expressed and Secreted (RANTES) and stromal derived factor—1α (SDF-1α) were shown to be significantly elevated (p < 0.001 for RANTES and p < 0.007 for SDF-1α) in patients with at least severe NPDR compared with those with less severe DR (Meleth et al., 2005). The gene discussed is CXCL12; the disease is non-proliferative diabetic retinopathy.