To this end, we performed a genetic study to determine the effect of Prss56 ablation in a mouse model of myopia caused by a null mutation in Egr1. EGR1 is a known regulator of ocular axial growth, and Egr1 expression is up- or down-regulated in animal models with experimentally-induced reduction or increase in ocular axial length, respectively [46, 47] Importantly, mice lacking EGR1 (Egr1-/-) recapitulate the characteristic hallmarks of myopia including increased ocular axial length and a myopic refractive shift [31]. The gene discussed is PRSS56; the disease is myopia.