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Phenylketonuria (PKU)

What is phenylketonuria (PKU)?

Phenylketonuria (PKU) is a rare genetic condition that causes a buildup of the amino acid phenylalanine. Amino acids are obtained through the dietary intake of protein, and phenylalanine is present in protein as well as some artificial sweeteners. The buildup of phenylalanine in the body can lead to serious health problems. PKU affects 1 in 10,000-15,000 births.

What are the symptoms of PKU?

The symptoms of PKU are caused by a lack of breakdown and elimination of the amino acid phenylalanine. Newborns with PKU do not exhibit symptoms immediately after birth. Symptoms appear within the first few months of life. Early detection of PKU is important to avoid irreversible health problems. Symptoms of PKU include:

  • Seizures
  • Developmental delays
  • Intellectual delays
  • Hyperactivity
  • Decreased bone strength
  • Abnormally small head (microcephaly)
  • Fair skin and eyes due to poor melanin production
  • Skin rashes such as eczema
  • Musty odor to breath, skin and/or urine
  • Heart defects

What causes PKU?

PKU is caused by a mutation in the gene responsible for the adequate formation of an enzyme phenylalanine hydroxylase. This enzyme is responsible for the breakdown of the amino acid phenylalanine in the body. This genetic mutation must be inherited from each parent. If only one parent passes on the genetic mutation, the child will be a carrier.

Are there treatment options available for PKU?

Early detection of PKU is essential for successful treatment and avoidance of permanent damage such as irreversible intellectual disability. The main treatment of PKU is dietary adjustments. Treatments include:

  • Specialized bay formula due to the inability to consume breast milk or standard formula
  • Adult formula supplements
  • Avoidance of high protein foods such as eggs, cheese, nuts, milk, beans, beef, pork, and fish
  • Close monitoring of phenylalanine in the blood
  • Administration of Kuvan (sapropterin hydrochloride), a medication to reduce phenylalanine in the blood

Currently, there are initiatives working to get approval for insurance coverage to pay for PKU friendly foods found in specialty health food stores.

Where can I find more information about PKU?

Phenylketonuria (PKU) Articles