In the study of Lin and colleagues, mean serum levels of FGF21 in the control group, diabetic patients without retinopathy, patients with non-proliferative retinopathy, and patients with proliferative retinopathy were respectively 125.9, 326.8, 631.9, and 669.4 pg/mL, respectively. The gene discussed is FGF21; the disease is retinal disorder.