Phenylketonuria (PKU) is a rare, heritable disorder characterized by the buildup of an amino acid called phenylalanine in the body. (Amino acids are building blocks of proteins). This buildup can cause severe health problems if not addressed. A mutation in the PAH gene causes the disease, and ethnicity seems to be a important risk factor for inheriting PKU.
How do children inherit PKU?
To develop PKU, a child must have inherited to copies of the genetic mutation that causes the disease — one from each parent. Usually, the parents have no symptoms of the disease, and are considered carriers, each with one copy of the disease-causing mutation. If both parents are carriers, their children will have a 1 in 4 chance of inheriting both copies of the faulty gene and developing the disease. The children will also have 1 in 2 chance of inheriting one faulty gene and also be carriers like their parents. Finally, they will have a 1 in 4 chance of inheriting two healthy copies of the gene, and will not have the disease or be carriers.
How does ethnicity affect PKU risk?
The overall prevalence of PKU is on the order of 1 in 10,000 to 15,000 births in the U.S.
However, the incidence of PKU varies among ethnic groups, and is more common in people of European, Turkish, or Native American ancestry. Conversely, the disease is much less common (approximately 10 times less) in people of African and South Asian ancestry.
Who should be tested for PKU?
Most countries around the world screen newborns for PKU. If you belong to a high-risk ethnic group, you should get your baby tested at birth. This is because a special diet can ensure that the disease does not cause any complications.
If you have a family history of PKU or are of European, Turkish, or Native American descent, you may want to consider talking to a genetic counselor about genetic testing. The test can determine whether you are a carrier of the disease and your risk, if any, of transmitting it to the next generation. The counselor can discuss the pros and cons of the genetic test, and examine your family history to determine who else might need the test.
What happens if I am a carrier for PKU?
If you know you are a carrier of PKU, you should talk to your partner about getting tested before trying to start a family. If they are not a carrier, your children will not inherit the disease, though they may be carriers. However, if you and your partner are both carriers (or one of you is a carrier and one of you has PKU), you may want to talk with a genetic counselor about alternate reproductive technologies such as in vitro fertilization with pre-implantation genetic diagnosis.
Last updated: June 4, 2020
Phenylketonuria News is strictly a news and information website about the disease. It does not provide medical advice, diagnosis, or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.
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