What Is the PKU Disease?

Phenylketonuria, or PKU, is a rare birth defect that can cause high levels of phenylalanine due to the body's inability to break down this amino acid. Babies in many countries are routinely tested for phenylketonuria after birth.

Symptoms

• According to the Mayo Clinic, symptoms of phenylketonuria can develop a few months after birth and may include mental retardation, seizures and hyperactivity. Skin rashes and a small head size may occur with this disorder.

Complications

• Irreversible brain damage and behavioral problems can develop in patients with untreated phenylketonuria.

Causes

• Phenylketonuria is caused by a defective gene mutation that inhibits the production of an enzyme that the body normally uses to break down phenylalanine. A child must inherit the defective gene from both parents in order to develop phenylketonuria.

Risk Factors

• Native Americans and people whose ancestors came from northern Europe have a higher risk of being born with phenylketonuria.

Treatment

• Patients with phenylketonuria must observe a strict diet that is low in phenylalanine and avoid high-protein foods including milk, cheese and meat. Patients should get regular blood tests that measure phenylalanine levels.