Republic of the Philippines
CARAGA STATE UNIVERSITY
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A CASE STUDY ON INFANTILE, JUVENILE AND LATE ON-SET TAY-SACHS DISEASE WITH OBJECTIVE MEDICALDESCRIPTIONS & COMPILATION OF RELATED STUDIES
General Biology 2 – Galilei
Mr. Florence Jhun F. Almadin
Ma. Shiena R. Lagrimas
January 24, 2018
Tay-Sachs disease or also known as acute infantile variant (Kaback & Desnick, 2011) is a heritable disorder that mainly affects infants, adolescents and even adults. This basically targets the nervous system of the human body. It is caused by the absence of hexosaminidase-A (Hex-A), a vital enzyme found in the brain cells that functions in metabolizing certain lipids (Campbell, Reece, Urry, Cain, Wasserman, Minorsky & Jackson, 2015). Without the presence of these enzymes, the lipid (GM2 ganglioside) accumulates abnormally in cells, specifically in the nerve cells. After which, the on-going accumulation causes more damage to the brain.
The inheritable disorder commonly starts at early fetal development or during early stages of pregnancy. After child birth and up to the point where the child reaches the age of three to six months, he or she ‘appears’ to be normal. But as soon as the child turns two years older, symptoms of the disease is apparent wherein recurrent seizures and diminishing mental function usually takes place. The child will also be having a hard time crawling, turning over, sitting and even reaching out (U.S. National Library of Medicine, 2018). In the worst case scenario, it may lead to blindness, cognitive impairment, paralysis and non-responsiveness. And as soon as the child turns three or four years older, the nervous system becomes badly affected, eventually leading to death. On the other hand, adults are also susceptible to this kind of disease merely categorized as the Late-Onset Tay-Sachs disease causing intellectual and neurological impairment (National Human Genome Research Institute, 2011).
Because of the aforementioned effects of the said disorder and its progressive obliterations towards the nervous system of the human body, the researcher wrote this study to make the respective readers become aware of this rare and inherited disorder and to let them understand the nature, the causes, the overall symptoms, the effective management and preventive measures in order to preclude the possible occurrence of this disease.
As it is written in the previous section of the paper, the disease causes fatality common to infants experiencing motor and mental degeneration beforehand and even adults are no exemption to this type of disease. It has been discovered and known to experts in the certain field such as Campbell et al. (2015) that only children inheriting two copies of Tay-Sachs allele (homozygotes) have the disease. However, the relationship among alleles of a single gene—whether the alleles appear to be completely dominant, incompletely dominant or codominant depend only on the level at which the phenotype is analyzed (organismal, biochemical, and molecular level).
In relevance to these statements, a certain defect in the Hex-A gene primarily causes Tay-Sachs disease, wherein humans have two copies of the particular gene. And whether both of these Hex-A genes are active or just either of the two, the body will then be able to reproduce or secrete enough enzymes to hinder the irregular building up of the lipids particularly in the brain cells (NHGRI, 2011). While a person having both active and inactive gene is believed to be a ‘carrier’, he or she is still considered as healthy. But there is a fifty percent chance that the disease will be passed on to his or her future off-springs—making them potential carriers as well and will have greater chances of acquiring Tay-Sachs disease coming from their respective parents (if both parents happen to be carriers).
Mahuran (1999) also presented in his study that Tay-Sachs disease can be primarily caused by a certain deficiency on any of these proteins such as alpha-(HEXA gene), beta-(HEXB), and GM2 activator protein (GM2A) which eventually leads to storage of the ganglioside (the lipid), primarily in the lysosomes of neuronal cells.
In the study conducted by Utz, Crutcher, Schneider, Sorgen, & Whitley (2014) about the biomarkers of central nervous system inflammation in infantile and juvenile gangliosidosis, it shows that several associated with inflammation were elevated in the CSF of infantile gangliosidosis patients, and less so in more slowly progressing forms of juvenile gangliosidosis, but not in MPS disease. Also, in a related study done by Jarnes Utz, Kim, King, Ziegler, Schema, Redtree, & Whitley (2017) they were able to map the timeline of clinical changes evident in patients with infantile gangliosidosis through prospective evaluation and clinical care. And they have found out that children ages below 6 months old have hypotonia, children in their first year of age have severe motor skill impairment while seizures, dysphagia and feeding-tube placement are experienced by infants below or before of 18 months of age.
According to USNLM (2018), Tay-Sachs disease is very rare in the general population. The genetic mutations that cause this disease are more common in people of Ashkenazi (eastern and central European) Jewish heritage than in those with other backgrounds. It has been said that approximately one in every 27 Jews in the United States is a carrier of the Tay-Sachs disease gene (NHGRI, 2011).
In order to accomplish the objective of characterizing and determining the cognitive status in a sample of individuals with late-onset GM2 gangliosidosis (commonly referred to as late-onset Tay-Sachs disease), Zaroff, Neudorfer, Morrison, Pastores, Rubin, & Kolodny (2004) evaluated seventeen subjects, ages 18-56 years and were in various stages of disease progression. These patients underwent comprehensive neuropsychological assessment and it came out that nearly one-half of the sample scored in the impaired range on measures of processing speed, visual sequencing, and set shifting. One-third of the sample also scored in the impaired range on measures of delayed verbal recall. After the series of evaluation, researchers concluded that there is a risk of impairment in executive functioning and memory as well as cerebellar dysfunction among patients diagnosed with late-onset GM2 gangliosidosis.
Aside from the neuropsychological assessments and the impairments found in adults with Tay-Sachs disease (Zaroff, et al., 2004), most affected infants have nerve damage starting in the mother’s womb (before birth), with symptoms appearing from age 3 to 6 months. Progression is rapid in this case, and the child will typically pass away by 4 or 5 years old. Additional symptoms of Tay-Sachs among infants include: deafness, progressive blindness, seizure, muscular stiffness, slow growth, and red spot on the macula (an oval-shaped area near the center of the retina in the eye) (Healthline, 2005).
International efforts and initiatives have been done for early detection and diagnosis such as the works of Kaback, Lim-Steele, Dabholkar, Brown, Levy, & Zeiger (1993). Their objectives are to provide an update of the international experience with carrier screening and prenatal diagnosis for Tay-Sachs disease (TSD), to assess the impact of these efforts, and to review the recent developments in DNA technology with application to TSD carrier detection and screening through setting up Tay-Sachs disease testing centers for annual assessments and by doing interventions through Gene product screening (enzyme testing) and DNA-based mutation analysis (in some populations).
There are no available medical cures/remedies for the Tay-Sachs disease but certain treatments such as keeping the child comfortable or the so called ‘palliative care’ (Healthline, 2005). Palliative care may include medication for pain (pain killers) in order to ease or soothe the pain of these children by sending pain messages back to their brain through the special nerve endings. Painkilling drugs interfere with these messages, either at the site of the injury, in the spinal cord or in the brain itself (Science Museum, 2018). However, there are numbers of unpleasant side effects associated with painkiller abuse. Mild side effects include nausea, vomiting, and diarrhea, usually caused by the way the drug interacts with opioid receptors along the digestive tract. You can also expect random muscle spasms that occur as a result of the nerves reacting at random to various stimuli (Patterson, 2018).
Other treatments in minimizing or reducing the negative effects of the Tay-Sachs disease brought to children and even adults include: anti-epileptics (that are also helpful in controlling seizures), physical therapy, feeding tubes, and respiratory care to reduce mucus buildup in the lungs (Healthline, 2005).
Since Tay-Sachs disease is inherited, there is no way to prevent it except through screening. An individual can screen for carriers of the Tay-Sachs disease by doing genetic testing on two parents who are thinking about starting a family (NHGRI, 2011). Screening for carriers of Tay-Sachs was started in the 1970s, and has reduced the number of Ashkenazi Jews born with Tay-Sachs by 90 percent.
In the entirety, Tay-Sachs disease is primarily the result of deficient amount of the enzyme known as hexosaminidase-A, that is a crucial substance in breaking down lipids or gangliosides. Due to the insufficient amount of these enzymes, these lipids will otherwise fail to metabolize and will eventually accumulate along the brain cells specifically in the nerve cells. The abnormality occurring along the nerve cells will develop during early stages of fetal development or during pregnancy and will not be evident until the child reaches three to six months old. Children who are diagnosed with this type of genetic disorder will only have a shorter life expectancy compared to those children who do not have and will only reach five years at maximum. Symptoms of motor skills impairment, paralysis, deafness, blindness, loss of muscular strength etc., will be eminent among infants and even juveniles who have TSDs. Even so, adults are also susceptible to this type of genetic disorder leading to neuropsychological degeneration and is considered as the Late Onset Tay-Sachs disease.
No found cures are available at this point in time but several treatments are available such as the usage of pain killers, anti-epileptic drugs, and physical therapies. But some of these medications and medical practices should be taken into careful account since these do not only have beneficial effects but negative effects on the subject as well.
Lastly, the best way to prevent the rapid spread and progression of this disease among individuals and particularly, infants is to have their parents checked or tested with genetic tests or even simple blood tests that detect genes having Tay-Sachs disease and therefore, reducing the chances of pass ing on the inactive gene having lesser amounts of Hex-A to their offspring.
Electronic Sources / Basic Format (Internet sites):
Healthline. (2005). Healthline. Retrieved from Healthline Media: https://www.healthline.com/health/tay-sachs-disease#screening-and-prevention
Mahuran, D. (1999, October 8). PubMed. Retrieved from National Center for Biotechnology Information: https://www.ncbi.nlm.nih.gov/pubmed/10571007
National Human Genome Research Institute. (2011, March 17). Learning About Tay-Sachs Disease. Retrieved from National Human Genome Research Institute: https://www.genome.gov/10001220/learning-about-taysachs-disease/
Patterson, E. (2018). The Effects of Painkiller Use. Retrieved from Drug Abuse: https://drugabuse.com/library/the-effects-of-painkiller-use/
Science Museum. (2018). Who Am I? Retrieved from Science Museum: http://whoami.sciencemuseum.org.uk/whoami/findoutmore/yourbrain/howdodrugsaffectyourbrain/howdopainkillerswork
U.S. National Library of Medicine. (2018, January 16). Genetics Home Reference. Retrieved from U.S. National Library of Medicine: https://ghr.nlm.nih.gov/condition/tay-sachs-disease#definition
Electronic Sources Multiple Authors (Internet sites):
Jarnes Utz, J., Kim, S., King, K., Ziegler, R., Schema, L., Redtree, E., & Whitley, C. (2017, April 11). PubMed. Retrieved from National Center for Biotechnology Information: https://www.ncbi.nlm.nih.gov/pubmed/28476546?dopt=Abstract
Kaback, M., & Desnick, R. (2011, August 11). PubMed. Retrieved from National Center for Biotechnology Information: https://www.ncbi.nlm.nih.gov/pubmed/20301397
Kaback, M., Lim-Steele, J., Dabholkar, D., Brown, D., N, L., & Zeiger, K. (1993, November 17). PubMed. Retrieved from National Center for Biotechnology Information: https://www.ncbi.nlm.nih.gov/pubmed/8230592?dopt=Abstract
Utz, J., Crutcher, T., Schneider, J., Sorgen, P., & Whitley, C. (2014, November 15). PubMed. Retrieved from National Center for Biotechnology Information: https://www.ncbi.nlm.nih.gov/pubmed/25557439?dopt=Abstract
Zaroff, C., Neudorfer, O., Morrison, C., Pastores, G., Rubin, H., & Kolodny, E. (2004, June 22). PubMed. Retrieved from National Center for Biotechnology Information: https://www.ncbi.nlm.nih.gov/pubmed/15210895?dopt=Abstract
Campbell, N. A., Reece, J. B., Urry, L. A., Cain, M. L., Wasserman, S. A., Minorsky, P. V., & Jackson, R. B. (2015). Biology: A Global Approach (10th ed.). Edinburgh Gate, Harlow, Essex CM20 2JE, England: Pearson Education Limited.