Overall, we observed significantly elevated levels of C3 (p = 0.05), C4 (p = 0.001), CFH (p = 2.24 × 10−5), VEGF (p = 0.0027), apolipoprotein AI (p = 0.0007), and apolipoprotein CIII (p = 0.004) in the vitreous of ROP compared to the control subjects indicating their possible involvement in the disease pathogenesis (Figure 1A). This evidence concerns the gene C4A and retinopathy of prematurity.