Ocular Coloboma is a genetic disorder characterized, phenotypically, by an abnormal appearance of the iris. When the PAX6 gene (responsible for the development of the precursor lens of the eye) is mutated, it can cause Ocular Coloboma by not allowing for the effective closure of the embryonic fissure of the optic cup (O’Neill et al 1986). The PAX6 gene is located on the P arm of the eleventh chromosome (11p13) and is a member of a complex of proteins called the paired box gene family (OMIM 2013).
PAX6 is responsible for many different things during fetal development having to do with the brain, spinal cord, and pancreas. Ocular Coloboma can also occur with a variety of other disorders, such as mental retardation, absence of the corpus callosum, etc., due to the volume of neural tissues PAX6 is responsible for developing (OMIM 2013).
The cause of Ocular Coloboma is not well understood. It most likely an autosomal dominant mutation of the PAX6 gene, with some research supporting autosomal recessive inheritance. There is also some research supporting a dominant-negative mutation. A dominant-negative mutation is a gain-of-function mutation and is extremely rare (OMIM 2013). These types of mutations will usually result in some form of cancer, and the particular one that causes Ocular Coloboma occurs in approximately one of 10,000 people.
PAX6 functions to target genes through a paired-type DNA-binding domain, which is comprised of two binding subdomains; one is an N-terminal subdomain and the other is a C-terminal subdomain. In humans, the PAX6 gene is responsible for two alternatively spliced isoforms, each with a unique composition like that of the paired domain (OMIM 2013). This paired-type binding domain allows for exon 5a to work ...
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Herpin, A., Lelong, C., & Favrel, P. (2004) Transforming growth factor-beta-related proteins: an ancestral and widespread superfamily of cytokines in metazoans. Developmental & Comparative Immunology, 28, 461-485. Retrieved April 1, 2014, from http://www.ncbi.nlm.nih.gov/pubmed/15062644
Jonathan A. Epstein, Tom Glaser, Jiexing Cai, Lisa Jepeal, David S. Walton, and Richard Maas. "Two independent and interactive DNA-binding subdomains of the Pax6 paired domain are regulated by alternative splicing ." Genes & Development (1994): 2022-2034. PDF.
O'Neill, M. J. F., McKusick, V.A., Kniffin, C. L., Kelly, J. (1986). Ocular Coloboma. Online
Mendelian Inheritance in Man, , . Retrieved from http://omim.org/entry/120200?search=ocular%20coloboma&highlight=ocular%20coloboma#contributors-shutter
OMIM. PAIRED BOX GENE 6; PAX6. 26 September 2013. Website. 19 March 2014.
The widespread involvement of Retinal Pigment Epithelium (RPE), flat (placoid) nature of the lesions and absence of overlying serous retinal detachment and minimal choroidal involvement lead Gass to conclude RPE was primary focus of inflammation.(1) ...
Xeroderma Pigmentosum is a genetic disorder caused by a mutation in one of any seven genes. This genetic mutation is an autosomal recessive trait. This disease was discovered in 1874 by Hebra and Kaposi. People with this disease cannot have direct exposure to sunlight, or blisters on the skin may occur. There are only about 250 people in the world with this disease.
(Binder, 386). Other collagen-containing extraskeletal tissues, such as the sclerae, the teeth, and the heart valves are also affected to a variable degree. OI has a "common feature of bony fragility associated with defective formation of collagen by osteoblasts and fibroblasts." (Smith, 1983, 13) This disease, involving defective development of the connective tissues, is usually the result of the autosomal dominant gene, but can also be the result of the autosomal recessive gene. Spontaneous mutations are common and the clinical presentation of the disease remains to be quite broad. (Binder, 386)
Hall, Linley Erin. “Understanding Genetics DNA and RNA.” New York: The Rosen Publishing Group, Inc., 2011. Print. 01 Apr. 2014.
Retinitis pigmentosa can be caused in a person in numerous ways. It normally runs in families, however, it can also be caused from a mutation. We believe my grandmother developed the disorder from a genetic mutation, as no one else in my family has ever had the disorder or has developed it as of...
According to Baily and Hall, while visual impairment early in life is associated with inherited congenital disorders, abnormal fetal devepment, and problems associated with premature birth, most eye conditions are associated with aging. They claim that over 70% of the visually impaired population in the United States is over 65. Age related maculopathy, also called macular degeneration, or AMD, impairs the center of vision in older individuals. The macula is the region in the back of the retina that surrounds and includes the fovea (Goldstein 1999). It is important to understand that when this degeneration progresses enough, the condition constitutes blindness because the foveal area is what is used to focus on something. Most cases do not progress this far, but between five and 20% do. Allikments and Shroyer claim that 11 million people in the United States alone suffer some degree of this impairment, with 75% of those individuals being 75 or older. Seven percent of this older age group reportedly suffer advanced forms. Freidman reports the disease as most common in developed countries.
It is a rare condition that affects 2 % of Americans. Signs of pathological myopia include: Bending or distortion of straight lines, altered color perception, reduced contrast sensitivity, and increasing gloss of central vision. It is a quick severe progression of myopia and loss of vision is the end result. There is an increased risk of retinal detachment and other degenerative changes in the back of the eye (bleeding from abnormal blood vessel growth). If any of these things occur the risk of cataracts could increase. Treatment calls for a combination of a drug and a laser procedure called photodynamic therapy. It is reported to be the seventh ranking cause of legal blindness in the United States of America the fourth ranking cause in Hong Kong and the second in parts of China and Japan this form of myopia frequently progresses in adult life, with small intermittent steps of elongation being observable at any age. The adult progression appears to be due to the stretching of the walls of the eye. Genetically weak elements of the scleral wall are prone to thinning and stretching. One of the major forces at work in this stretching process appears to be the normal intra-ocular pressure (Ward
... starts relaxing the supercoils and altering of DNA and interacts with DNA helicase SGS1 and plays a role in DNA recombination, also cellular aging and maintenance of genome stability. Alternate splicing results in multiple transcript variants. Additional spliced variants of the gene have been described, but their complete length is unknown.
There's a disease that lurks among young children even to this day. It's a direct result of a mutation in the genes that could result in the removal of the eye. Both boys and girls are affected, and one in every fifteen to thirty thousand babies is infected every year (Ambramson, Ch1). This eye corrupting, chromosomal abnormality shows up in about 300-350 new cases each year. It is called retinoblastoma.
Web. 15 Apr. 2014.
Lynch syndrome (HNPCC), a change/mutation in certain genes which may allow the formation of small growths of tissue called polyps. These polyps are normally not cancerous, but the ones mostly seen in the Lynch syndrome are called adenoma, which...
Microdeletion On Chromosome 7. The Ambassadors Online Magazine. N.p., July 2008. Web. 19 Feb. 2014. .
The patient is a 43 year-old female insurance sale agent who came to the clinic for annual eye examination. She complained from symptoms of ocular irritation and burning when she wakes up in the morning. She felt ocular dryness in the afternoon and the eyes look red. She has also noted different height of her eyelids when putting make-up on. She denied significant problems with driving, TV watching, computer use or reading. She also denied flashes, floaters or diplopia. The patient was myopia with no prior eye surgeries, previous history of eye trauma, amblyopia or strabismus. She did not use any medication. The past ocular family history was negative. Social history was negative, too.