pku webquest

PHENYLKETONURIA: A METABOLIC DISORDER

Metabolic disorders are genetic diseases that affect the body's ability to perform its normal chemical reactions. Many metabolic disorders result from enzyme defects. Recall that a metabolic pathway is a stepwise sequence of enzyme-mediated reactions. If one enzyme in a metabolic pathway is defective, that enzyme's substrate may accumulate and the pathway may not be completed. This may result in a buildup of harmful substances or a shortage of required molecules.

Activity

In this exercise, you will use the Web links below to gather information about the metabolic disorder phenylketonuria (PKU). Use what you learn to answer the questions at the bottom of the page.

Your Genes, Your Health: Phenylketonuria

http://www.ygyh.org

NSPKU Home Page

http://www.nspku.org

Baby’s First Test (Look up “Classic PKU”)

Newborn Screening in Colorado

Phenylketonuria - The Genetics

http://willroberts.com/pku/

Some possible questions for your research:

1. What enzyme is most commonly defective in people with phenylketonuria?

the PAH enzyme

2. What reaction does this enzyme catalyze? (What is the substrate and what product is produced?)

the reaction is cause is the build up of the phenylalanine poison in the brain which causes epilepsy and mental retardation.

3. Describe the symptoms of phenylketonuria.

a child can have a smaller than normal head, epilepsy, and mental retardation

4. What causes the symptoms of PKU, the lack of a substance or the buildup of one? Explain.

the cause is the build up of  phenylalanine poison  in the brain which is caused by a person not having a good PAH enzyme in their brain.


5. How common is phenylketonuria? How is it treated?
PKU appears in 1 in 10,000 births in caucasians and east asians. some ethic groups have higher rates, (e.g., turks- 1 in 2,600; irish- 1 in 4500), and some have lower rates (e.g., Japanese- 1 in 143000) the disorder is exceedingly rare in africans. it is treated by having the child to adhere to a low protein diet as soon as the disorder is diagnosed and should stay on the diet as long as possible. even after the age of 12 relaxation of the diet can change a persons behavior. some doctors recommend the have the diet for life.