Retinitis definition11/15/2023 RISK FACTORS AND CAUSES: Most patients have genetic inheritance. Fundus photographs of a patient diagnosed with retinitis pigmentosa (left) and a healthy individual (right). Central vision may be lost over time.įigure 1. Although the disease usually occurs during childhood and adolescence, it may emerge at any age. It starts with a deterioration in the ability to see in darkness and continues with a decrease in visual ability and loss of peripheral vision. Genetic counselors are excellent resources for discussing inheritability, family planning, genetic testing, and other related issues.DEFINITION: Retinitis pigmentosa (RP) is the common name for the diseases of cell communities in the retina called rods, which allow us to see in a dark and dim environment. If a family member is diagnosed with RP, it is often advised that other members of the family also have an eye exam by a physician who is specially trained to detect and treat retinal degenerative disorders. Female carriers have a 50 percent chance (or 1 chance in 2) of passing the X-linked disease gene to their daughters, who become carriers, and a 50 percent chance of passing the gene to their sons, who are then affected by the disease. Males with X-linked diseases pass their Y chromosome to their sons, and therefore will never pass an X-linked disease to their sons. Males have only one X chromosome (paired with one Y chromosome) and are therefore genetically susceptible to X-linked diseases. ![]() Because they have a healthy version of the gene on their other X chromosome, carrier females are less frequently affected by X-linked diseases. Females have two X chromosomes and can carry the disease gene on one of their X chromosomes. ![]() In X-linked RP, the mutated gene for the disease is located on the X chromosome. The unaffected parent genetics doesn’t play a known role in the inheritance of the disease. A child has a 50 percent chance of being affected through the inheritance of the mutated copy from. In autosomal dominant RP, usually one parent is affected and is the only parent with a mutated copy of the gene. If the child inherits one mutated copy from one parent, they will be an unaffected carrier. Each of their children has a 25 percent chance of being affected by inheriting a mutated copy from each parent. They are therefore referred to as unaffected carriers. In autosomal recessive RP, both parents carry one copy of the mutated gene and one normal copy, but have no symptoms themselves. ![]() Genetic mutations can be passed from parent to offspring through one of three genetic inheritance patterns - autosomal recessive, autosomal dominant, or X-linked. (Cells need the proper amount of particular proteins in order to function properly.) Mutations in dozens of genes have been linked to RP. The mutated gene gives the wrong instructions to photoreceptor cells, telling them to make an incorrect protein or too little or too much protein. have RP, mainly caused by mutations (variations) in a single gene inherited from one or both parents.
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