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intro and the genetic

Submitted by ziweiwang on Thu, 12/05/2019 - 21:30

Retinitis pigmentosa is a degenerative monogenetic disorder of the retina that affects about 1 million people worldwide. People who are affected by the disease slowly lose their vision until they go blind. In retinitis pigmentosa, only the rod cells are affected, creating a unique characteristic at genetic, protein, cell, and tissue level, and have unique challenges in treating the disease. 
The disease usually progresses with prolonged time to adjust to the dark followed by the inability to see in the dark, and restriction in vision. While disease progression differs significantly between different people, most people lose their sight eventually. Because of this the patients often face unique challenges such as being aware that they may have the disease because there are family members that have the disease. Like many people who have a progressive vision illness that ends in blindness, people often have a harder time adjusting to blindness compared to those who were born blind. However, they also tend to be more accepting of the fact that they will be blind compared to those who lose their vision suddenly, with people indicating that things were not as bad as they thought. Other challenges that the people who have this illness must face is the challenge of learning braille, using walking sticks, inability to drive and fear of losing their job or not being hired due to their illness. People who have the blindness describe their sight as though they are walking into a dark room with sunglasses on. The peripheral vision fades first and when the disease advances enough, the vision appears to be narrowed, almost as though looking through a tube. Despite the challenges that the disease poses, it is not fatal, and only vision is lost. 
There are many different modes of inheritance in retinitis pigmentosa, including autosomal dominant, autosomal recessive, x linked and mitochondrial linked. However, RHO  P23H mutation on chromosome 3, also known as RP4 is autosomal dominant and is the most common form of the disease.  The disease was first discovered in the 1970s, with the mutation to be determined in the gene RP1. For the autosomal dominant RP caused by the mutation of P23H rhodopsin gene mutation, the genetic defect was discovered in a large Irish family that had early retinitis pigments for 5 generations in 1989. The paper also tried to establish that the mutation was on chromosome 3. In 1990, a paper established that the P23H mutation in the RHO gene was what caused the disease.