Stargardt disease gene

However, the loss of vision is only noticed in adulthood. People with the disease rarely become completely blind. The loss of vision slowly progresses from the normal 20/20 to 20/200 over time or even worse (nei. nih. gov). org). Patient Details John’s father brought him to White River Family Eye Care complaining of inability to adapt to bright light and inability to see things clearly. John is an adolescent male who is 16 years of age. John started complaining about inability to see clearly since he was 12 years old. He lives in White River Junction, VT. Possible Diagnoses and Reasons The first thing that came to my mind after consultations with John and his father is that John could have been suffering from myopia couples with photophobia.

Myopia is a refractive error in the eyes which causes objects located at a distance to appear blurred. It can affect people at any age (allaboutvision. com). The reason for this diagnosis is that John suffered from blurred vision, had to squint in an effort to see things clearly and experienced frequent headaches, which can be said to be as a result of the strain exerted on the eyes as he tried. com). It causes one to have blurred vision at all distances. The main reason I came up with this diagnosis is that John did not state that he was having problems seeing objects at a particular distance. He just stated that objects appeared blurred and cloudy. Objects appearing blurry at all distances is a sign of astigmatism.

nih. gov). The ophthalmologist can use a standard eye chart or other tests. i. Testing the visual field This test involves testing the patient’s visual field and serves to show the distribution and sensitivity of the visual field as well as determine whether there is any actual loss in his central or peripheral vision. Lipofuscin is fluorescent by nature. It glows in the dark when the eyes are shined with light. With this test, I was able to identify yellow flecks that were irregularly shaped projecting out of the macula in a ring-like pattern. This indicated the presence of lipofuscin deposits in the retina and the possibility of Stargardt Disease in John. However, I could not use these two tests alone to state that John was suffering from Stargardt Disease.

It stands for ATP-binding cassette, sub-family A member 4 (nucleotide # 861-862 and change from TT-AA). The disease name is Stargardt Disease. OMIM recognizes the disease. I used OMIM to search for the assigned gene sequence which enabled me to identify the name of the disease that is caused ABCA4 gene mutation, which is Stargardt Disease. Other genetic mutations causing this disease Stargardt’s disease is mainly caused by mutations in the ABCA4 gene. gov). The ELOVL4 gene codes for the protein ELOVL4 that makes very long-chain fatty acids. ELOVL4 is active in the retina. Mutations in the ELOL4 gene causes aggregates of the protein ELOVL4 that build up and interfere with the functions of the cells of the retina, causing them to die (ghr.

nlm. nih. gov). The ABCA4 gene is not sex-linked. Two copies of the mutant gene must exist for the child to have the disease because the ABCA4 mutant gene is recessive, meaning it only expresses itself phenotypically in the homozygous state. A person with only one copy of the recessive gene mutation is a carrier. nih. gov). It is found that everyone person in every 10000 people is suffering from the Stargardt disease. According to the data corrected in the United Kingdom, there were 81 cases reported of the diseases in 12 months (Sparrow et al. The results indicated that there is an annual incidence rate of the disease of 0. How mutation changes amino acid sequence The mutation changes the amino acid # 286 and at the premature stop codon.

The Wild-Type and its Gene Structure Wild type gene: ABCA4, chromosomal map location: chromosome 1p, band 22. # of exons =50 and # intron 49. Wild-type protein Wild type protein produce: RIM protein, size: 2273amino acid, function: Retina photoreceptor> look more into the RIM protein function (using primary literatures). Wild-type protein conserved domains and their functions Using the wild-type conserve domain: RIM Function: it is a photoreceptor protein (rim protein) in eukaryotes. This causes waste deposits like lipofuscin to accumulate in the RPE (retinal pigment epithelium), which is usually the layer that provides nutritional support to the cones and rods in the retina (macular. org). The accumulation of waste causes the rods and cones as well as the RPE to break down. The disease does not have a cure.

However, eye protection and proper nutrition may delay its progression. The long-term prognosis of the disease depends on the age of onset of the genetic alleles. The disease normally progresses to the legal blindness level of sickness to the majority of its victims (Sparrow et al. In addition to this, the condition does not affect the life expectancy of the patients, and hence they normally experience normal life expectancy. The normal onset of the disease during childhood and the main cause of this are due to genetic inheritance from parents. Possible complications of this disease are a blurred vision to the majority of the patients of this disease. com/conditions/blurry-vision. htm https://www. allaboutvision. com/conditions/lightsensitive. htm https://www.