Tay-Sachs Disease By: Madison SHUMATE

What is Tay-Sachs disease? Tay-Sachs disease, most commonly found in children, is a fatal autosomal recessive genetic disorder that progressively destructs the nervous system. The cause of Tay-Sachs disease is due to the absence of a vital enzyme called hexosaminidase-A (Hex-A). Without Hex-A, a fatty substance called GM2 ganglioside gathers abnormally in cells, especially in the nerve cells of the brain. Progressive damage to the cells can be caused by this ongoing gathering.

Who discovered Tay-Sachs disease? Warren Tay, in 1881, found a “cherry red spot” in the retina of a one-year-old child with mental and physical retardation. In 1896, in the autopsy tissue of affected children Bernard Sachs found extreme swelling of neurons. Also noted by Sachs is that the disease appeared to run in families of Jewish origin. Both, Tay and Sachs, had defined the same disease, but the swelling of neurons and the material that caused the cherry-red spot wasn’t identified as a ganglioside lipid until the 1930s. It could also be recognized as an “inborn error of metabolism” after identified as a lipid.

Information on Tay-Sachs disease Tay-Sachs disease affects the 15th chromosome. Everyone has two of these chromosomes, when one isn’t working their just a carrier, but can pass on the disease to offspring. When both chromosomes aren’t working the person has Tay-Sachs disease. The gene that is miscoded for Tay-Sachs disease is the HEXA gene. In the gene that codes for Hex-A, the DNA-based carrier test searches for specific mutations. Also, another carrier test for Tay-Sachs disease is a simple blood test.

Information on Tay-Sachs disease Unfortunately, there are no treatments available for Tay- Sachs disease. Even though there isn’t a treatment for patients, things are still done to ensure that the patient is comfortable and supported. There are medications, respiratory care (due to the risk of lung infection), a feeding tube (to prevent the cause of respiratory problems, and physical therapy (to help keep the ability to move). However, the Tay-Sachs Gene Therapy Consortium is working towards gene replacement therapy. They have done some trial test with laboratory mice, which has been successful and affective. For more information on the program and its studies visit http://www.tsgtconsortium.com/reports.html .

Symptoms Most infants who are affected begin to have nerve damage in the utero, and usually 12 to 24 weeks after birth symptoms will appear. Symptoms include: deafness blindness decreased muscle tone increased startle response paralysis or loss of muscle function seizures delayed mental and social development slow growth red spot on the macula (an oval-shaped area near the center of the retina in the eye) http://www.healthline.com/health/tay-sachs-disease#Symptoms4

Prognosis/ Life expectancy As stated, Tay-Sachs disease is a fatal disease. Most cases of Tay-Sachs disease are found in infants. The infants that are affected have a life expectancy to live anywhere from 4-5 years. For More Information on Tay-Sachs disease: http://ghr.nlm.nih.gov/condition/tay-sachs-disease http://www.genome.gov/10001220 Organization: National Tay-Sachs and Allied diseases (http://www.tay-sachs.org/taysachs_disease.php)

Interesting Facts Ashkenazi Jews (families of eastern Europe) are found to be the most frequent carriers of Tay-Sachs disease. If both parents are carriers the percentages will be: 25% Normal child: 50% Carrier child: 25% Child with Tay-Sachs disease http://denisewilbon.blogspot.com/ http://4.bp.blogspot.com/- 0qLPFyqZp38/TVQgMtFWZHI/AAAAAAAAAAk/RSCQytAE3P8/s1600/thumbnailCA5VZ9RV.jpg

Pedigree

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Sources (continued) http://www.tay-sachs.org/screening_standards.php http://4.bp.blogspot.com/- 0qLPFyqZp38/TVQgMtFWZHI/AAAAAAAAAAk/RSCQytAE3P8/s1600/thumbnailCA5VZ9RV.jpg http://denisewilbon.blogspot.com/ http://www.tay-sachs.org/research.php http://www.mayoclinic.org/diseases-conditions/tay-sachs-disease/care-at-mayo- clinic/treatment/con-20036799 http://www.jpgmonline.com/articles/2008/54/1/images/jpgm_2008_54_1_54_39196_2.jpg