Down’s Syndrome is named after John Langdon Down, a British doctor who first studied and described the mental disorder. He discovered the disorder in Surrey, England while working at an asylum for children with mental retardation. He called people with this disorder Mongoloids because of the physical similarities of citizens from Mongolia compared to those affected by Down’s Syndrome. Later, the term “Mongoloid” was dropped and named after John Down when Jerome Lejeune, a French geneticist who tested children with these similar physical characteristics of Mongolians, found that 97% of those tested had an extra chromosome-21, with a total of 47 chromosomes. Down’s Syndrome is a common disorder due to an extra chromosome number; it is the most common cause of mental retardation that occurs in 1 in 1,000 babies in the United States. (Genetic Science Learning Center)
There are three types of Down’s Syndrome: Trisomy 21, Translocation, and Mosaicism. Trisomy 21 is the most common type of Down’s Syndrome; it occurs in 95 percent of Down’s Syndrome cases. Trisomy 21 is a disorder in which a newborn receives an extra third chromosome-21, instead of the normal 2. The second type of Down’s Syndrome is Translocation; it occurs when only a small piece of the chromosome-21 is found on another chromosome. Only 3 percent of those with Down’s Syndrome suffer from Translocation. Mosaicism is the third type of Down’s Syndrome and also the rarest; it is a disorder in which newborns have a mix of cells in the chromosome-47 that contains an extra chromosome-21. Only 2 percent of people with Down’s Syndrome possess Mosaicism. (Hauser-Cram, 15)
Causes of Down’s Syndrome are still unknown. There is no way to prevent the occurrence of Down’s Syndrome, and there are no medications or remedies to stop it from taking place. Since it is very unusual for parents to contribute an extra chromosome-21, it is almost physically impossible to have 2 children with the disorder; the chance of it occurring twice is less than 1%. (Skallerup, 29)
People with Down’s Syndrome have the following physical characteristics: flat face, round cheeks, long tongue, yellowish skin, small nose, poor coordination and low muscle tone. A mere extra chromosome causes those who suffer from Down’s Syndrome to possess these physical characteristics. Lack of development in the facial muscles causes those with Down’s Syndrome to look very similar to one another. Due to these similar physical characteristics, Down’s Syndrome is the most recognized mental disorder.
There are three pre-natal diagnostic tests: Chronic Villus Sampling, Amniocentesis and Ultrasounds. Chronic Villus Sampling is a test in which a tiny tissue sample is taken from outside the amniotic sac; it is performed between 8 and 12 weeks of pregnancy. Secondly, Amniocentesis is a medical procedure in which about 15-20 milliliters of fluids from the amniotic sac are taken from the mother’s abdomen between 12 and 20 weeks of pregnancy...