Phenylketonuria

By Lillian Trauger

What is Phenylketonuria?

Phenylketonuria, also known as PKU, is an inherited metabolic disorder that affects the way the body breaks down protein. It was discovered by Asbjorn Folling(on right), a Norwegian doctor, in 1934.

What does PKU do to the body?

PKU increases the levels of the amino acid Phenylalanine(left) in the blood. Because of this, Phenylalanine can build up excessively, causing some serious health problems, including intellectual disability.

What are the symptoms and side effects of PKU?

The symptoms of PKU can either be mild or severe. A baby's breath, skin, and/or urine may have a musty odor. The baby may also have a small head, slow growth, and seizures. People who have PKU also may have lighter skin and hair than their unaffected family members. Some side effects of PKU include delayed development, psychiatric disorders, and behavioral problems. The people who have PKU also have to watch what they eat, and avoid foods with a lot of protein.

What type of disease is PKU, and how do you get it?

PKU falls into the category of being a single gene mutation disorder, and is an autosomal recessive disorder. This means that the parents must both have the mutations in their genes for one of their children to have PKU. Even though a parent may be a carrier, they may not have the symptoms of PKU. The chart on the left shows how someone can get PKU. The only way you can have PKU is if you are born with it.

Is there anything I should know about the inheritance of PKU?

PKU is a recessive trait, and only about 1 in 15,000 babies are born with PKU. The gene for the disorder is located on chromosome 12, which is on the left. PKU is not more likely to occur in certain populations than other populations. There are no environmental factors or influences.

Is there any tests performed to determine if someone has PKU?

Yes. After birth, all babies have a blood test, and blood is taken from their heel to see if they have PKU or another disease. This test is required in all 50 states, and because of that, it can be treated as soon as possible.

Is there anything else I should know about PKU?

There are three groups that PKU can be classified in: Classical, which is the most common type, Moderate, which has a bit more tolerance for Phenylalanine but still be on a restricted diet, and Benign, where the signs of PKU are still there but there is no dietary restrictions. PKU is also known as Folling's disease. There are several hundred babies diagnosed with PKU every year. However, the study on PKU and other genetic disorders are continually advancing, so there is always more information available.

Is there any treatment for PKU, and is there an effect on life expectancy if you have PKU?

PKU is incurable, but the people have PKU have to be on a restricted diet to reduce the risk of too much Phenylalanine building up. There are also medications such as Kuvan(left), which helps reduce Phenylalanine blood levels. If you have PKU, it does not affect your life expectancy.

Is there any organizations or support groups to help individuals and/or their families with PKU?

Yes, the National PKU Alliance(NPKUA), the National Society for Phenylketonuria(NSPKU), and the PKU Foundation are just a few of the many organizations and support groups out there.