A new gene mutation that causes blindness and is carried by one in 23 Jews of Yemenite origin, as well as others of different origin, has been discovered by researchers at the Technion-Israel Institute of Technology in Haifa. The discovery, which affects couples that both carry the mutation, will enable the identification of carriers and genetic counselling to high-risk families. Scientists at the Technion's Rappaport Medical School published its findings in the latest issue of the journal Investigative Ophthalmology and Visual Science. Retinitis pigmentosa is a hereditary eye disease that results from the gradual degeneration of the retina, said Dr. Tamar Ben Yosef. She conducted her research with master's degree student Noa Auslander, in cooperation with Prof. Eyal Benin and Dr. Dror Sharon of Hadassah-University Medical Center in Jerusalem's Ein Kerem. Most victims of this disease suffer first from the loss of their night vision, often in childhood, and then from gradual loss of their field vision during the day, until they become blind around the age of 20. It is the most common cause of hereditary retinal degeneration. The prevalence of the mutation in the world is one-in-3,500 individuals. Over the past few years, the researchers collected DNA from many families with members suffering from the disease, including one large one of Yemenite origin, and identified the gene, which is called CERKL. CERKL mutations are very rare in people who are not of Yemenite origin. The gene is recessive, meaning that the risk for disease is 25 percent in each child born to two carriers.