Considering the roles of NGF, BDNF, TH, and EPO in retinal neurodevelopment, as well as vascularization [24,25,26,27,28], homeostasis, and stress regulation [18,19,29,30], we hypothesize that functional polymorphisms in these genes may contribute to the risk of ROP development. The gene discussed is TH; the disease is retinopathy of prematurity.