This is a causal analysis paper written on the causes and affects of Tay-Sachs Disease.
Christina Arcidiacono
ENG 104
November 2011
The Fatal Truth of Tay-Sach’s
Couples thinking about having children constantly worry about what their risk of having a child with a life changing disease is. With genetic testing, doctors are now able to test both parents for recessive mutated genes that they may pass on to their child. “If both parents carry the recessive mutated gene for a disease (which means that they do not have the disease, but are carriers), the risk of their child having the disease is about 25%” (Sheth, 2010). The percentage is 25% because the child must inherit both recessive genes in order to have the disease.
Tay-Sach’s disease is “a disorder that severely affects the nerve functioning in infants” (I. Guttilla, personal communication, October 10, 2011). The disease “is caused by a defective gene on chromosome 15” (Sheth, 2010). “The genetic mutation that causes Tay-Sach’s is recessive” (I. Guttilla, personal communication, October 10, 2011). A recessive genetic mutation means that the disease will only show its characteristics when it is paired with an identical allele. As stated previously, both parents must carry and pass on the mutated gene, which is on chromosome 15, for their child to have Tay-Sach’s disease. Research has shown that Tay-Sach’s appears to be “common among the Ashkenazi Jewish population” (Sheth, 2010). “In the Ashkenazi Jewish population, about 1 in 27 people are carriers, compared to 1 in 250 of the general population” (Bartoshesky, 2011).
“The defective gene on chromosome 15 prevents the synthesis of hexosaminidase A” (Sheths, 2010). “Hexosaminidase A, or Hex A, is an enzyme protein found in the lysosomes of human cells that aids in the breakdown of gangliosides, which is a chemical found in nerve tissues” (Sheth, 2010). Without the Hex A protein, gangliosides, or particularly ganglioside “GM2, cannot be digested” (I. Guttilla, personal communication, October 10, 2011). In other words, without the Hex A enzyme, “fatty proteins and other unwanted material that can interfere with growth, are not being cleared out of the cells” (Bartoshesky, 2011). One may wonder, so what happens to the GM2 and other unwanted materials which cannot be digested? Given the lack of the Hex A protein in a Tay-Sach’s victim, residual vacuoles accumulate “in nerve cells in the brain” (Sheth, 2010). As the buildup progresses, effects of this genetic disease begin to take away pieces of the victim’s life.
Without the ability to break down ganglioside GM2 in the lysosomes of the cells, the accumulation of lipids, or residual vacuoles, builds up in the brain. This particular genetic mutation affects the central nervous system and causes severe nerve damage. “Even though nerve damage usually begins in the womb, symptoms of Tay-Sach’s frequently appear around the ages of 3 to 6 months old” (Sheth, 2010). Symptoms that display the effects of Tay-Sach’s disease include but are not limited to “blindness, gradual hearing loss, inability to move, and respiratory issues” (I. Guttilla, personal communication, October 10, 2011). However, the symptoms do not occur all at once. Rather, the symptoms occur “gradually during the next few months, or even years, after the first appearance around 3-6 months old” (Bartoshesky, 2011). The symptoms progress over time due to the increase of buildup of lipids in the brain.
When individuals are diagnosed with Tay-Sach’s disease, it evidently ends up shutting down their entire central nervous system due to the buildup of lipids in the nerve cells. Therefore, as the symptoms progress, children “stop smiling, crawling, turning over, and reaching out for things” (Bartoshesky, 2011). This is simply because they have lost the ability to physically do such behaviors. As young as 2 years of life, “the child may have seizures and even become completely disabled” (Bartoshesky, 2011). In many cases of the disease, the child ends up “dying by the age of 5” (I. Guttilla, personal communication, October 10, 2011). “However, in more minor cases of the disease, hearing, sight, and mental capabilities remain intact, but muscle weakness and slurred speech linger” (Bartoshesky, 2011). There are also rare forms of the disease in which the Hex A enzyme is present, but there is not enough of it. “In rare cases such as this, symptoms do not appear until about 2-5 years. As well, the disease progresses at a much slower rate. Still, death tends to occur around the young age of only 15 years” (Bartoshesky, 2011).
Tay-Sach’s disease is just one of many fatal diseases caused by a genetic mutation. Sadly, if both parents are carriers of the recessive mutation and the child receives both bad copies, the child’s life will be cut short. Therefore, genetic testing is offered for couples thinking of starting a family. By completing the genetic testing, couples can learn about the likelihood of their child being born with a disease caused by a genetic mutation, such as Tay-Sach’s. Even though there is not a cure for Tay-Sach’s disease, there are treatments that can aid in controlling the distressing symptoms. “Medication can be prescribed in order to control the symptoms. In some cases, hospital respiratory care may be required to help with breathing and frequent infections. As the victim begins having trouble swallowing, feeding tubes can also be inserted in order to provide necessary nutrients. There are also physical therapy sessions offered that can help optimize joint flexibility and range of motions” (I. Guttilla, personal communication, October 10, 2011). The treatments for Tay-Sach’s disease are helpful in making the victim’s short life as pleasant as it can possibly be.
References
Sheth, K. (2010, November 17). Tay-sach's disease. Retrieved from http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0002390/
Bartoshesky, L. (2011, May). Tay-sach's disease. Retrieved from http://kidshealth.org/parent/medical/genetic/tay_sachs.html