Johns Hopkins researchers at the Wilmer Eye Institute have discovered what appears to be the first human gene mutation that causes extreme farsightedness. The researchers report that nanophthalmos, Greek for "dwarf eye," is a rare, potentially blinding disorder caused by an alteration in a gene called MFRP that helps control eye growth and regulates the organ's shape and focus. The study is published in the Proceedings of the National Academy of Sciences. The research team successfully mapped the MFRP gene mutation in humans and discovered that the protein was completely missing from nanophthalmos patients. In a normal human eye, the MFRP protein is located on the surface of the retinal pigment epithelium (RPE), which is located beneath the retina and helps maintain photoreceptors, the eye's light-detecting cells. Blindness occurs when these cells die after detachment of the retina from the RPE.