Galactosemia Essay

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Galactosemia is an inborn error of metabolism. Because of energy barriers, essentially none of the chemical reactions that take place in living things could occur at any measurable rate without the presence of a catalyst. Most catalysts in living things are enzymes that depend on their structure to be able to function. Their structure is determined by their coding on DNA. Inborn errors of metabolism, like the one seen in galactosemia, are caused by defective genes.
Galactosemia is an inherited metabolic disorder in which the transformation of galactose to glucose is blocked, allowing galactose to increase to toxic levels in the body (Chung 1997). Galactose epimerase, the enzyme in the liver that
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High levels of galactose cause vomiting diarrhea, lethargy, low blood sugar, brain damage, jaundice, liver enlargement, cataracts, malnutrition, rapid organ damage, susceptibility to infection especially to gram negative bacteria, and even death (Olendare, Jenyan, and Bayden 1999 and Chung 1997). Infants may also exhibit poor growth, feeding difficulties, encephalopathy, and renal tubular dysfunction (Berry et al. 1995).
The Human Genome Project has had a great impact on what is known about galactosemia. They have identified what causes the disease and on which chromosome the mutation occurs. Three enzymes are required to completely convert galactose to glucose-1-phosphate, which is able to enter the metabolic pathway and turn into energy. A separate gene encodes each of these three enzymes. If any of these enzymes fail to function galactose builds up and galactosemia result (Olendore, Jenyan, and Bayden 1999).
The first type of galactosemia is called galactosemia I or classic galactosemia. This form has been discovered to be caused by defects in both copies of the gene that codes the enzyme galactosemia-1-phosphate-uridyl transferase (GALT) (Olendore, Jenyan, and Bayden 1999). This enzyme is responsible for the second phase of galactose metabolism. Without this enzyme, the body cannot

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