A 28-year-old woman with well-controlled PKU (plasma phenylalanine maintained at 240 µmol/L pre-conception) plans pregnancy. Her physician warns that maternal phenylalanine above 360 µmol/L during pregnancy causes congenital heart disease, microcephaly, and intellectual disability in the infant regardless of the infant's PAH status. What is this called?
- A Teratogenic phenylalanine effect
- B Maternal PKU syndrome ✓
- C Congenital hyperphenylalaninemia
- D Phenylalanine embryopathy
Correct answer: B. Maternal PKU syndrome
Explanation
Maternal PKU syndrome describes the teratogenic effect of elevated maternal phenylalanine on a fetus who may not even carry a PAH mutation. The fetus is exposed to high phenylalanine via placental transfer, causing microcephaly, congenital heart defects (especially tetralogy of Fallot), and intellectual disability. Strict phenylalanine control must begin pre-conception.
Reference: Williams Obstetrics, 26th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.