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Retinitis pigmentosa other wise known as RP is a rare genetic disorder that effects an estimated 1 in every 4000 people. RP is inherited and is a broad disease that can be from any one mutation in 50 chromosomes. Genetic disorders are passed on in three main ways:
- autosomal recessive inheritance is where the disease can only be expressed when they have a homozygous recessive pair usually from two unaware carriers (the child would have a 50% chance of being a carrier; a 25% chance of expressing the genetic disorder; and a 25% of having neither)
- autosomal dominant inheritance means that just one copy of the gene would be enough for the offspring to have the disease (the child would have a 50% chance of being a carrier and a 50% chance of having the disease)
- X-linked inheritance happens when the mother has a genetic disorder that is carried in the X chromosomes but is balanced out by the other one however a son born with this trait would express the disease)
With RP, it is normally passed on through the dominant gene.

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To better understand the way RP effects vision, we must know how the eye functions. The cornea which is the outer layer of the eye helps to direct the light further into the pupil. Here, it goes to the lens where it is focused onto the retina. It can also be noted that the amount of light let in is adjusted according to the brightness of the surrounding environment by the iris (the colored part around the pupil). The photo receptors (which can be divided into rods that line the edge of the retina and work in dark or dim light; and cones that reside in the center of the retina and allow you to see detail and color) convert the light into electrical signals that travel along the optic nerve to the brain. Here, it is interpreted and forms the image you see.

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The mutated genetic material that causes RP breaks down the retina and results in loss of vision. There are several different types of RP:
- a severe form where the cell is unable to create the proteins that are needed to function
- another form where the cell makes harmful toxins that damage the retina
- and a form where the cells in the retina create abnormal proteins that can't carry out all the necessary processes
RP usually develops in childhood and can begin with night and peripheral blindness stemming from the loss of rod cells. Later, more and more cones die and tunnel vision is expected. It becomes harder and harder for people with RP to recognize faces, read, drive, and walk. Also, people with RP have a difficult time adjusting to sudden changes in light and may have photo phobia - a name that refers to the fear of bright light. Some may even loose their eye sight entirely when they reach adulthood.

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Doctors are able to use a few methods to identify RP. One includes a device called an ophthalmoscope which is able to  see the retina. Often, it appears to have dark streaks across it where the cells are dying - this is where the genetic disorder gets its name from (retinitis pigmentosa). Another way that RP can be diagnosed is through the use of tools such as Electoretinograms (ERG) which detect the response of the rods and cones when a bright light is flashed. Visual Field Testings can map out a patients view by seeing the extent by running a test where the person presses a button when they are able to see a dot moving around on a screen so that a doctor can tell the extent of their sight and whether or not they have tunnel vision (a telling sign of RP). Genetic testing can be done as well to see the chances of the following generation to inherit the disease. Pre-natal tests are possible however they are mostly for X-linked types.

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Help can be given to people with RP by specialists like occupation, orientation, mobility, and low vision therapists. These experts are able to assist disabled people with everyday tasks that they can modify to fit that particular person's needs so they may regain their independence. Many use guide dogs to help them stay mobile. For children in school, the curriculum can be altered to better cater for a child with RP and there are computer programs that can read aloud text. There has also been some evidence that shows taking vitamin A palmitate slows the progression of the genetic disorder. There are several new technologies too such as lenses that can magnify central vision and prevent glare or the Argus 2 (which is still being designed and changed today) that is a light-sensitive electrode surgically implanted behind the retina to replace the photo receptor cells that connects to a pair of glasses. These have cameras that wireless transmit data to the brain through the prosthetic retina. Gene therapy is also being used to cure RP by inserting a healthy copy of a gene into the diseased area. This can be accomplished in a number of ways:
- plasmid DNA (genetically engineered molecules are used to carry a healthy piece of DNA to the mutated region)
- bacterial vectors (modified bacterium carry therapeutic genes into human tissue)
- gene editing technology (fixing mutated genes)
- patient derived cellular gene therapy (cells from the patient are altered before being returned to the body)
Blindness Support Services are located in places like 3696 Beatty Dr # A, Riverside, CA 92506

where people can connect to peers.

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fda.gov
nei.nih.gov
researchgate.net
rarediseases.org

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As you can see, the second set of chromosomes on the right (B) has one extra chromosome.

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Here, an occupational therapist helps a child with blindness.

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This is an ERG used to help diagnose RP.