Down syndrome

Essay by JenniferSessionsUniversity, Bachelor'sA+, October 2004

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In 1866, an Englishman, named John Langdon Down, published the first clinical description of the condition that is now called Down syndrome (Capone 2004). According to Turner & Alborz (2003), Down's syndrome occurs in approximately one in six hundred live births per year. Also known as Trisomy 21, Down syndrome is a common birth defect caused by an error in cell division. This error in cell division causes the person to have an extra portion on the number 21 chromosome present in all, or some, of their cells. According to Berk (2003), this additional genetic material alters the course of development and causes the many characteristics associated with the syndrome. This one extra copy of the gene should lead to a fifty- percent increase in its corresponding protein. "Consequences of even small portions in up to 150 proteins is difficult to predict" (Capone, 2004, p. 47). Experiments with Down syndrome are done with mice.

The genes found on the human chromosome 21 are also found on three different mice chromosomes, this makes mice the most promising approach to understanding Down syndrome (Roizen & Patterson 2003).

Down syndrome effects the individuals that have it in many ways. Individuals with Down syndrome have distinct physical features, including a short, stocky build, a flatten face, almond shaped eyes, a protruding tongue, and an unusual crease running across the palm of their hand (Berk 2003). Many medical problems are also included in the affects of this birth defect. Some of these medical affects include mental retardation, memory and speech problems, hearing loss, limited vocabulary, and slow motor development. Since about one in 141 newborns with Down syndrome has persistent primary congenital hypothyroidism, it is standard care for children to be screened at six months old for thyroid disease. Individuals with Down syndrome...