Down Syndrome Essay -- Biology Biological Medical Essays

Down Syndrome They used to be called "Mongoloids," an ethnic insult coined by John Langdon Down, an English physician during the nineteenth century. But now they are known as people, individuals with a condition known as Down syndrome. (3). It wasn't until the 1960s that Jerome Lejeune and Patricia Jacobs discovered the cause of Down syndrome (also called trisomy 21). But with technological advancements within the scientific community, more and more information has been gathered about the condition that affects about one in every one thousand children born around the world. (4). Research shows that Down syndrome is a genetic condition caused by certain chromosomal abnormalities. Chromosomes within cells are composed of proteins and genetic information in the form of DNA. Human cells normally contain 23 pairs of chromosomes to make a total of 46 chromosomes in each cell. When sex cells (eggs and sperm) divide through the process of meiosis, one cell splits into two parts so that each of the resulting cells only has 23 chromosomes, rather than 46. But many errors can occur during cell division. During meiosis, the chromosomes are supposed to split and go to different areas of the cell. This step in the process of meiosis is called disjunction. But sometimes during cell division, a chromosome will not detach and it will stay with its pair chromosome. This results in one of the new cells having 24 chromosomes and the other having only 22 chromosomes. An error such as this is called nondisjunction. If a cell with this error mates with a normal cell, the fert ilized egg will end up with an uneven number of chromosomes. (3). In the instance of Down syndrome, 95 percent of all cases are caused by nondisjunction, and 90 p... ... some cells, researchers get closer and closer each year to discovering the mystery of trisomy 21. With every new development, and with increased education and research, the quality of life improves for the people who, not long ago, were exiled from society for being "different" from other people. Internet Sources: 1)"Prenatal Screening for Down Syndrome", http://www.ds-health.com/prenatal.htm 2)"Comprehensive Speech and Language Treatment for Infants, Toddlers, and Children with Down Syndrome", http://www.ds-health.com/speech.htm 3)"Trisomy 21: The Story of Down Syndrome", http://www.ds-health.com/trisomy.htm 4)Down Syndrome: Background Information", http://www.nas.com/downsyn/faq1.html 5)About Down Syndrome", http://www.ndss.org/aboutds/aboutds.html#PPgenetic 6)About Down Syndrome http://www.ndss.org/aboutds/aboutds.html#PPmedical