Patients with glutamate receptor 6 deficiency, present with congenital night blindness.14 Interestingly, the brain, skin, lens, optic nerve, cornea, and retina are all of ectodermal origin and therefore share similarities in expression and regulation of glutamate receptors.92, 93, 94 This suggests that disturbed glutamate homeostasis might not only affect the brain, but also these other ectodermal structures. Here, GRIK2 is linked to congenital stationary night blindness.