Essay about Down Syndrome

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Down Syndrome

Down syndrome is the most common genetic disorder among children. 1 out of every 1,000 is diagnosed with what is more commonly known as DS (Leshin, 2000). DS was first observed in 1866 by John Langdon Down, an English physician. However, only speculation existed on what caused this debilitating disease. In 1959, Jerome Lejeune and Patricia Jacobs discovered the true cause. It is trisomy of the 21st chromosomes that causes DS and the debilitating characteristics along with it (Leshin, 2000).

Chromosomes are string like structures that contain DNA and other compounds. They are the information center of living organisms. DNA can be broken down into smaller parts called genes, which contain traits of the
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The 21st chromosome holds 200-250 genes, which is considered to be the smallest chromosome in terms of genes (Leshin, 2000). However, the abundance of these genes causes overexpression, which simply means that there is an overabundance of “products” coded by the 21st chromosome. Only a small portion of the alleles present in the chromosome produce the effects of DS. These portions, however small, occur in several areas along the strand called the Down Syndrome Critical Region (Leshin, 2000). There are a diverse amount of traits caused by trisomy 21.

The brain is greatly affected by DS; not only in development, but in its overall structure. When compared to a normal brain, an affected brain has a considerably lower weight and the brain stem and cerebellum are small with respects to the cerebral hemispheres (CChem, 2003) Other abnormal characteristics include a round shape, foreshortened, steep rise of the occipital lobes, extreme narrowing of the superior temporal gyri and incomplete opercularization with exposure of the insular cortex, and reduced secondary sulcal development (CChem, 2003). These abnormalities are causes of diminished and malformed growth of the frontal and temporal lobes secondary to impaired neuronal differentiation (CChem, 2003). The severe changes in the brain cause irregular development of the individual.

Development of children with DS is closely

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