Down syndrome: A Genetic disorder
Each year in the United States, about 13 out of every 10,000 babies are born with Down syndrome, also called trisomy 21 (Johnson). Being the “most common chromosome disorder and genetic cause of intellectual disability”, Down syndrome equally affects males and females as well as all different races (Johnson). In other words, Down syndrome does not show any preference for a specific gender or race. Unfortunately, those who are affected by Down syndrome experience a number of problems throughout their lives which limit their quality of life and health.
Down syndrome is caused by the existence of a third 21’s chromosome, shown in Figure 1. This can occur through one of three possible processes, all resulting in Down syndrome. The first and most common cause of Down syndrome occurs during cell division and involves the failure of all chromosomes to separate properly, resulting in an extra chromosome in the daughter cell (Down). This process can be referred to as nondisjunction (Down). The second cause, called cell line mosaicism, is the result of the abnormal division of a single cell. Because of this, those affected by mosaic Down syndrome have cells with normal numbers of chromosomes as well as cells with one extra chromosome (Down). “Individuals who are mosaic for trisomy 21 typically have less severe signs and symptoms of the disorder” (Down). The third cause of Down syndrome is called Chromosome translocation and involves a structural problem with the 21st chromosome rather than a numerical problem (Down). Chromosome translocation occurs when two 21 chromosomes become attached, leaving the chromosome number technically normal but still resulting in Down syndrome (Down). The Mosaic and Chromosome translocation causes for Down syndrome are much rarer than the Nondisjunction cause (Down).
Down syndrome is usually diagnosed at birth through a series of recognizable symptoms and traits (Johnson). “Infants with Down syndrome tend to be overly quiet, less responsive, with weak, floppy muscles. Furthermore, a number of physical signs may be present. These include a flat appearing face; smaller than normal head; flat bridge of the nose; smaller than normal, low-set nose; small mouth, with a protruding tongue; upward slanting eyes; extra folds of skin located at the inside corner of each eye, near the nose (epicanthal folds); small, outwardly rotated ears; small, wide hands; an unusual, deep crease across the center of the palm (simian crease); malformed fifth finger; wide space between the big and the second toes; unusual creases on the soles of the feet; and, later in childhood, shorter than normal height” (Down). Mental retardation also appears in those with Down syndrome in varying degrees. Because of this, childhood development is delayed and people with Down syndrome often require special education and other special services (Johnson). When diagnosis is suspected, a chromosome analysis can be given to...