In patients with ROP, known mutations in 4 genes—Norrin (NDP), BDNF variants (development factor associated with the brain), low density lipoprotein receptor-related protein (LRP5), and frizzled family receptors 4 (FZD4)—aggravate this disease but they are rare [1]. The gene discussed is FZD4; the disease is retinopathy of prematurity.