Phenylketonuria
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[edit] General
Phenylketonuria (sometimes called PKU) is a congenital disease (a disease a person is born with) where a person's body cannot break down an amino acid called phenylalanine. Amino acids are necessary to make proteins, which is what the human body is made out of. Phenylalanine only comes from the food we eat; our bodies do not make any by themselves.
[edit] How it works
Normal people produce an enzyme called phenylalanine hydroxylase in their bodies. When they ingest phenylalanine, the body can't use it, so this enzyme changes phenylalanine into tyrosine, which the body can use. In people with PKU, very little or no enzyme is made. Since the phenylalanine they eat isn't being changed into tyrosine, it builds up in their bodies. This can cause problems with the way their bodies work.
[edit] Symptoms
- Itchy rashes
- Small head
- Shaking or jerking motions
- Seizures
- Hyperactivity (lots of energy)
- Mental retardation
- Urine or sweat smells strange (some people think it smells like mice)
- Light coloration (pale skin, blonde hair and blue eyes)
[edit] Treatment
In the past, children with PKU almost always died from having too much phenylalanine in their bodies. Today, scientists know what foods have phenylalanine in them, and they have created a special diet for people with PKU. Since they can't use it, people with PKU can't eat foods that have a lot of phenylalanine, like eggs, meat and milk. An artificial sweetener called aspartame, which is used to flavor diet sodas and candies, also has a lot of phenylalanine, so people with PKU have to be careful to avoid anything with aspartame in it. People with PKU also have to take a lot of vitamins to make up for the foods they can't eat, especially vitamins B6 and B12.
Babies with PKU are fed a special formula called Lofenelac. It has everything babies need to stay healthy, but with very little phenylalanine.
Women with PKU who are pregnant or trying to get pregnant have to be especially careful to follow this diet. If they do not follow the diet, their babies could be born with severe birth defects and mental retardation. Babies born to women with PKU who have followed the PKU diet throughout their pregnancy are usually healthy and do not necessarily develop PKU. Whether or not they have PKU themselves depends on the mother and father's genes.
[edit] Future
Most people with PKU can live as long and healthy as anyone else if the low-phenylalanine diet is started when they are babies and continued for the rest of their lives. The symptoms will usually disappear after the diet is started.