Down syndrome - Research Paper Example

Down Syndrome Running head: DOWN SYNDROME Down Syndrome In APA Style Down Syndrome 2 Charles Darwin, a famous evolutionist, Arthur Miller, a famous American playright, Eva Longoria, a well-known actress and Jamie Foxx, a hip-hop artist. All of them come from different backgrounds and fields of interest but there is one thing that ties them all together: Down syndrome. These famous people have a family member who is affected by this condition. According to the National Down Syndrome Society (2009), Down syndrome is most common single cause of human birth defects and the most commonly occurring chromosomal condition. One in every 733 babies is born with Down syndrome. Currently, there are more than 400,000 people living with Down syndrome in the United States alone. An estimated 3-4 million people are living with Down syndrome worldwide. As global healthcare improves, the population of people with Down syndrome may double over the next 30 years (Down Syndrome Education International, 2009). Down syndrome was first described by John Langdon Down, an English physician, when he recognized the cluster of traits common in people and published his findings in 1866. In 1959 Dr. Jeremy Lejeune discovered the fact that all people with this syndrome had an extra 21st chromosome. Down syndrome is defined medically as a genetic condition in which a person has exhibits an extra chromosome, having 37 instead of the normal 36 chromosomes. Chromosomes are rod-like structures located inside the nucleus of our cells which carry all the genetic information responsible for all our inherited characteristics. Normally, each cell contains 23 pairs of chromosomes, half of which are inherited from each parent. Down syndrome occurs when some or all of a person's cells have an extra full or partial copy of chromosome 21 (National Down Syndrome Society, 2009). There are three types of Down syndrome: nondisjunction, translocation, and mosaicism. The most common of these three, occuring in about 95% of all Down Syndrome 3 cases is nondisjuntion, often referred to as Trisomy 21. This error in meiosis (cell division is reproductive cells) occurs either before or at the time of conception wherein a pair of the 21st chromosomes in either the egg or the sperm do not separate properly. This extra chromosome is then found in every cell in the body causing the characteristics of Down syndrome. Translocation occurs in 3-4% of cases and with this type of error, a part of chromosome 21 breaks off and attaches itself to another chromosome. The most common chromosome being attached to is chromosome 14. Similar to nondisjunction, all the cells in the body have an extra piece of the 21st chromosome. Translocation is associated with one parent carrying chromosomal material that is unusually arranged, thereby, the only means of inheriting Down Syndrome. According to Mayoclinic.com (2007), if the father is the carrier, the risk is about 3 percent and if the mother is the carrier, the risk is about 12 percent. The third and least common type is mosaicism, which occurs in about 1-2% of all people with Down syndrome and the error in meiosis occurs after fertilization. This results in some fetal cells having 46 chromosomes and some with 47 chromosomes. The extent of physical problems will depend on the ratio of cells with 46 chromosomes to those with 47 chromosomes (About-down-syndrome.com, 2006). The third and least common type is mosaicism, which occurs in about 1-2% in Down syndrome cases. As mentioned earlier, the severity of signs and symptoms depend on the extent and type of mutation in the chromosomes of the person afllicted with Down syndrome. However, according to the Lewis & Kimsre (2009), common physical signs include: decreased muscle tone at birth, excessive skin at the nape of the neck, flattened nose, separated sutures (joints between the bones of the skull), single crease in the palm of the hand (Simean crease), small ears, small mouth, upward slanting eyes, wide, short hands with short fingers and white spots on the colored Down Syndrome 4 part of the eye (Brushfield spots). Upon birth, these patients may also present with birth defects with the cardiovascular system (such as an atrial septal defect or ventricular septal defect), eye problems (such as cataracts), gastrointestinal blockages (such as esophageal atresia and duodenal atresia), hearing problems, hip dislocation, sleep apnea (intermittent cessation of breathing) and hypothyroidism (underactive thyroid) (Lewis & Kimsre, 2009). They also may have atlantoaxial instability which may lead to spinal cord injury (SCI). They often have small statures (usually not reaching adult height) and small head circumferences. Persons with Down syndrome may also present with some form of mental retardation and motor, social and language developmental delays. The exact cause of the genetic mutation in Down syndrome is still undetermined. Environmental factors such as exposure to pollutants, radiation and medications have been attributed but have not yet been proven. Down syndrome has no disposition to any particular race. There have been, however, risk factors identified in the incidence of Down syndrome. The risk for having a child with Down syndrome increases as the maternal age increases. By age 35, a woman's risk of conceiving a child with Down syndrome is 1 in 385. By age 40, the risk is 1 in 106. And by age 45, the risk is 1 in 30 (Mayoclinic.com, 2007). Also, couples who already have a baby with Down syndrome have an increased risk of having another baby with the same condition. The American College of Obstetricians and Gynecologists recommends offering Down syndrome screening tests to all pregnant women, regardless of age. The "Triple Screen", also known as Bart's Test, is the most commonly administered screening test for Down syndrome. It Down Syndrome 5 tests the maternal serum for alpha-fetoprotein (AFP), human chorionic gonadotropin (hCG), unconjugated estriol (UE3). High levels of hCG and low levels for AFP and UE3 is associated with Down syndrome. Prenatal diagnostic tests such as percutaneous umbilical blood sampling (conducted after 18 weeks of gestation), amniocentesis (conducted between 12 and 20 weeks gestation), or chorionic villus sampling (conducted between 8 and 12 weeks) are strongly advised for copules who may have translocated chromosome 21. (Lewis & Kimsre, 2009). Postnatally, chromosome karyotype (genetic testing) is a test to identify and evaluate the size, shape, and number of chromosomes in a sample of body cells. This will determine if a person has Trisomy 21. Current researches have been focusing on the genetic causes of Down syndrome. According to Wiseman, Alforf, Tybulewicz & Fisher (2008), recent paper has suggested that trisomy of the Hsa21 genes, dual specificity tyrosine-(Y)-phosphorylation-regulated kinase 1A (DYRK1A) and regulator of calcineurin 1 (RCAN1), may have an impact on the development of multiple tissues .In the findings published in the American Journal of Human Genetics, the extra chromosome in Down syndrome disturbs a key regulating gene called NRSF or REST. DYRK1A is a priming kinase that facilitates the further phosphorylation of numerous proteins by other kinases. It is up-regulated in a number of tissues from people with DS. As a result, certain cell functions are uninhibited, ultimately leading to the physical problems manifested with Down syndrome. Another recent research authored by Olson, et.al (2007), focused on a small segment of Hsa21 known as the 'DS critical region' (DSCR) has been held to contain a gene or genes Down Syndrome 6 sufficient to cause impairment in learning and memory tasks involving the hippocampus. Their report, similar with previous studies, contends the DSCR hypothesis that one or a few genes are adequate to account for pathogenesis resulting in the production of a number of major, complex Down syndrome phenotypes. Olson, et.al (2007) concluded that the phenotypic outcome is the product of dosage effects of multiple genes affecting developmental processes and functions, a condition that argues strongly against a simple one gene - one phenotype explanation for the myriad effects seen in Down syndrome. Another study done by Patterson (2008) explores the possible link between folate deficiency and the risk of Down syndrome for the fetus. Folate deficiency has been associated with slowed growth, anaemia, weight loss, digestive disorders and some behavioural issues. However, several studies done have conflicting conclusions and further analysis and trials should be done to expound on this theory. As of present, there is no specific treatment for Down syndrome. Treatment for Down syndrome is usually symptom-based and requires a multidisciplinary team of health practitioners and special educators. Early intervention programs should begin as early as after birth to address the congenital defects as well as prevent further complications. Life expectancy has increased significantly over the last two decades. With current medical advances in research and the widening of public awareness of Down syndrome, patients with Down syndrome, their families, loved ones and all the people whose lives they affect can a future full of hope and optimism. Down Syndrome 7 References About-down-syndrome.com. (2006). Down Syndrome: Types of Down Syndrome. Retrieved March 29, 2009, from http://www.about-down-syndrome.com/types-of-down-syndrome.html Down Syndrome Education International. (2009). Down Syndrome. Retrieved March 27, 2009, from http://www.downsed.org/ Lewis, R.A & Kirmse, B (2009). Down Syndrome. Retrieved March 27, 2009, from http://www.nlm.nih.gov/medlineplus/ency/article/000997.htm Mayo Clinic Staff. (2007). Down Syndrome: Causes and Risk Factors. Retrieved March 27, 2009, from http://mayoclinic.com/health/down-syndrome National Association of Down Syndrome (2009). Facts on Down Syndrome. Retrieved March 27, 2009, from http://www.nads.org/pages_new/facts.html National Down Syndrome Society (2009). Down Syndrome Fact Sheet. Retrieved March 28, 2009, from http://www.ndss.org/index.phpoption=com_content&view=article&id=54&Itemid=74 Olson LE, Roper RJ, Sengstaken CL, Peterson EA, Aquino V, Galdzicki Z, et al. (2007). Trisomy for the Down syndrome 'critical region' is necessary but not sufficient for brain phenotypes of trisomic mice. Human Molecular Genetics. 16 (7), 774-82. Down Syndrome 8 Patterson D. (2008). Folate metabolism and the risk of Down syndrome. Down's Syndrome, Research and Practice : the Journal of the Sarah Duffen Centre / University of Portsmouth. 12 (2), 93-7. Wiseman FK, Alford KA, Tybulewicz VL, & Fisher EM. (2009). Down syndrome--recent progress and future prospects. Human Molecular Genetics. 18 (R1), 75-83. Read More