Period 3
December 18, 2009
Down Syndrome Down syndrome results from an irregular number of chromosomes and is present in about 1 in every 800 babies. More than 400,000 people living in the United States have Down syndrome. It can occur in people of all races and economic levels. Down syndrome is the most common genetic disorder. Down syndrome, also called trisomy 21, is a condition in which an individual has three copies of chromosome number 21. Down syndrome results from a defect called nondisjunction. Nondisjunction is when two chromosome pairs fail to separate during the division of the cells. This results in each sperm or egg cell having one chromosome from each pair. During fertilization, sperm and egg join together to create an embryo. Nondisjunction in chromosome number 21 can result in a sperm or egg cell receiving both copies of that chromosome. If that egg or sperm undergoes fertilization with a normal egg or sperm cell, the offspring would have three copies and be born with Down syndrome. It also is a condition in which extra genetic material causes delays in the way the child develops, both physically and mentally. A baby inherits Down syndrome at the time of conception (Matthews, p. 1). Low muscle tone, small stature, an upward slant to the eyes, short head, small head, flat nose, and short, stubby hands are a few physical characteristics of individuals who have Down syndrome. Every person with Down syndrome may posses these traits at different degrees or not at all. People with Down syndrome experience cognitive delays. These people have a higher risk of certain medical conditions such as congenital heart defects, respiratory and hearing problems, Alzheimer’s disease, leukemia, and thyroid conditions. The majority of these conditions are treatable, so most people with Down syndrome lead happy, healthy lives ("Syndrome”, p. 1). Down syndrome may be diagnosed before birth or shortly afterwards during a baby’s first physical exam. The diagnosis for Down syndrome before birth is based on ultrasound measurements of the fetus and lab test results. The diagnosis after birth is usually based off of how the baby looks. The mouth staying open with the tongue sticking out is a characteristic doctors use to help diagnose the baby (Braydon, p. 1). They also look to see if the baby’s eyes have a slant to the openings with extra skin at the corners. To confirm the diagnosis, they use a blood test, called a chromosomal karyotype. This involves “growing” the baby’s cells from their blood for about two weeks. Then they use a microscopic visualization of the chromosome to determine if extra material from chromosome 21 is present. The doctor who makes the diagnosis has no way of knowing the physical and intellectual capabilities of the child ("Future", p. 5) Children with Down syndrome are able to learn to walk, run, use their hands and eyes, understand language, think, and speak. However, children with Down syndrome learn to do these things at a slower rate than most other kids. They also have trouble with reasoning and judgment than other children. They have a have a very short attention span. Children with Down syndrome also are very impatient and can become frustrated and angry very easily. As the child reaches their teenage years, they become more aware of their limitations. At this age, emotional problems sometimes occur. Staying active at home, school, and in community activities is recommended to help with their emotional problems (Braydon, p. 2). The average life expectancy for people with Down syndrome in 1929 was nine years. The average life expectancy for people with Down syndrome today is 50 years and older. Many people with Down syndrome can form relationships and even get married. With the help of family and friends, adults with Down syndrome have the ability to obtain the skills needed to keep a job and live semi-independently. Premature aging and memory loss are two