By Mayo Clinic Staff

Untreated phenylketonuria can lead to:

  • Irreversible brain damage and marked intellectual disability within the first few months of life
  • Neurological problems such as seizures and tremors
  • Abnormally small head (microcephaly)
  • Behavioral, emotional and social problems in older children and adults
  • Significant health and developmental problems
Nov. 26, 2014