The retina contains two types of photoreceptors, rods and cones. The genes associated with cone-rod dystrophy play essential roles in the structure and function of specialized light receptor cells (photoreceptors) in the retina. Changes in at least two genes cause the X-linked form of the disorder, which is rare. Mutations in the GUCY2D and CRX genes account for about half of these cases. At least 10 genes have been associated with cone-rod dystrophy that is inherited in an autosomal dominant pattern. Mutations in the ABCA4 gene are the most common cause of autosomal recessive cone-rod dystrophy, accounting for 30 to 60 percent of cases. Approximately 20 of these genes are associated with the form of cone-rod dystrophy that is inherited in an autosomal recessive pattern. Mutations in more than 30 genes are known to cause cone-rod dystrophy. Additionally, cone-rod dystrophy can occur alone without any other signs and symptoms or it can occur as part of a syndrome that affects multiple parts of the body. There are more than 30 types of cone-rod dystrophy, which are distinguished by their genetic cause and their pattern of inheritance: autosomal recessive, autosomal dominant, and X-linked. As the condition progresses, individuals may develop involuntary eye movements (nystagmus). Decreasing visual acuity makes reading increasingly difficult and most affected individuals are legally blind by mid-adulthood. Over time, affected individuals develop night blindness and a worsening of their peripheral vision, which can limit independent mobility. These features are typically followed by impaired color vision (dyschromatopsia), blind spots (scotomas) in the center of the visual field, and partial side (peripheral) vision loss. The first signs and symptoms of cone-rod dystrophy, which often occur in childhood, are usually decreased sharpness of vision (visual acuity) and increased sensitivity to light (photophobia). In people with cone-rod dystrophy, vision loss occurs as the light-sensing cells of the retina gradually deteriorate. These disorders affect the retina, which is the layer of light-sensitive tissue at the back of the eye. Send us feedback about these examples.Cone-rod dystrophy is a group of related eye disorders that causes vision loss, which becomes more severe over time. These examples are programmatically compiled from various online sources to illustrate current usage of the word 'retinitis.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Bryce Alderton, Daily Pilot, 20 June 2017 The two most common kinds of retina disorders are retinitis pigmentosa and macular degeneration, which together affect about more than 20 million Americans. Candy Sagon, charlotteobserver, 9 June 2017 Andrei was afflicted with a retinal degenerative disease known as retinitis pigmentosa, which can cause vision impairment or vision loss. 2017 The Argus II, a bionic retina approved by the Food and Drug Administration, is now being used by more than 100 people with retinitis pigmentosa and other related conditions. Recent Examples on the Web Chaudhri suffers from retinitis pigmentosa, which causes degeneration of the retina.
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