The research team, which included lead author Neena B. Haider, an HHMI-supported graduate student in Sheffield's lab, Samuel G. Jacobson at the Scheie Eye Institute at the University of Pennsylvania, Edwin M. Stone from the department of ophthalmology at Iowa, and other collaborators, published its findings in the February 2000 issue of the journal Nature Genetics. Photoreceptors are specialized light-sensitive nerve cells that line the retina. Humans have two types of photoreceptors, called rods and cones. Rods mediate black and white vision and are used mainly at night. During the day, however, humans depend on cones for color vision.
Cones come in three types red, green, and blue that are sensitive to different wavelengths of light.
ESCS is a rare degenerative disease of the retina. Patients with ESCS suffer from night blindness and increased sensitivity to blue light. These observations led researchers to speculate that ESCS is caused by mistakes early in photoreceptor development that cause an overabundance of blue cones relative to the number of red and green cones. They did, however, think PNR a good candidate for other eye diseases, so they screened nearly 400 DNA samples from people with other eye disorders, and found two samples that possibly contained a PNR mutation. Now we had a hypothesis that mutations in this gene cause this specific syndrome.