Down Syndrome Research Paper

Down syndrome is a mutation that occurs when an individual has a partial or full extra copy of chromosome 21. The additional chromosome changes the course of development and causes the well known characteristic changes associated with down syndrome. A few of the common physical traits of down syndrome are small stature, low muscle tone, and an upward slant to the eyes. However, each person affected with down syndrome is unique and may possess these characteristics to different levels. Down syndrome was discovered in the late nineteenth century by english physician, John Down. Down was the first person to give an accurate description of people affected by down syndrome. In 1866 John Down was recognized as the father of down syndrome. In 1959 …show more content…
Trisomy 21 is the most common type of down syndrome accounts for 95% of the cases. Down syndrome is usually caused by an error in cell division, called “nondisjunction.” Nondisjunction results in an embryo with not two but three copies of chromosome 21. As the embryo develops, the extra chromosome is duplicated in every cell of the baby's body. Mosaicism is the least common form of down syndrome and only accounts for 1% of cases of down syndrome. Mosaicism is diagnosed when there is a mixture of two types of cells, some with the usual 46 chromosomes and some with 47. The cells with 47 chromosomes contain the extra 21 chromosome. Scientific studies have shown that individuals with mosaic down syndrome have less characteristics of down syndrome than other types of down syndrome. Translocation, which only accounts for around 4% of cases of down syndrome, the total number of chromosomes in the cells stays 46. However, an additional full or partial copy of chromosome 21 clings to another chromosome, most commonly chromosome …show more content…
There are two different categories of testing for down syndrome prenatally: screening tests, and diagnostic tests. Prenatal screens only estimate the chance of the baby having down syndrome. However, diagnostic tests can provide a definitive diagnosis with almost 100% accuracy. There is an absurd amount of prenatal screening tests available. Many of the screening tests involves a blood test and an ultrasound. The blood test measures the various substances in the blood of the mother, and combined with the mother’s age, they estimate the chance of the baby having down syndrome. A sonogram is performed with the blood tests to check for markers. All of these screens will not diagnose the baby with down syndrome. The diagnostic procedures available are chorionic villus sampling(CVS) and amniocentesis. These procedures are nearly 100% accurate in diagnosing. Amniocentesis is performed in the second trimester between 15 and 20 weeks of pregnancy, CVS in the first trimester. At birth down syndrome is usually diagnosed by the presence of certain physical traits: slightly flattened facial profile, low muscle tone, and an upward slant to the eyes. Because these features can be present in babies without Down syndrome, a chromosomal analysis called a karyotype is done to confirm the diagnosis. In order for the doctors to obtain a karyotype, they draw a blood sample to examine the baby’s cells. The doctors photograph the