Phenylketonuria (PKU): Symptoms & Signs

Medically Reviewed on 6/23/2020

Phenylketonuria (PKU) is an inherited (genetic) disorder that leads to increased levels of phenylalanine in the blood. If left untreated, the high phenylalanine levels can cause intellectual disability and other problems. PKU occurs in one out of every 10,000 to 15,000 newborns in the U.S.

Babies are routinely screened at birth for PKU. If not detected and treated, affected Infants appear normal until a few months old. Then, associated signs and symptoms can include

  • developmental delays,
  • seizures,
  • behavior disturbances, and
  • psychiatric problems later in life.

Other symptoms and signs can include lighter skin and hair than other family members and a musty or mouse-like odor due to excess phenylalanine.

Cause of phenylketonuria

A mutation in a gene known as PAH causes phenylketonuria.

Other phenylketonuria (pku) symptoms and signs

  • Behavior Disturbances
  • Developmental Delays
  • Lighter Skin and Hair Than Other Family Members
  • Musty Odor
  • Psychiatric Problems Later in Life
  • Seizures

Jameson, J. Larry, et al. Harrison's Principles of Internal Medicine, 20th Ed. New York: McGraw-Hill Education, 2018.