Skip to main content

Table 1 Current classification and treatment guidelines for PAH deficiency

From: Birth prevalence of phenylalanine hydroxylase deficiency: a systematic literature review and meta-analysis

Classification Pretreatment blood phenylalanine concentration Treatment recommended?
European guidelinesa ACMGb
Classical PKU  > 1200 µmol/L
(> 20 mg/dL)
Yes Yes
Moderate PKU 900–1200 µmol/L
(15–20 mg/dL)
Yes Yes
Mild PKU 600–900 µmol/L
(10–15 mg/dL)
Yes Yes
Mild HPA-gray zone 360–600 µmol/L
(6–10 mg/dL)
Yes (only if < 12 years or in women before/during pregnancy) Yesc
PAH deficiency not requiring treatment 120–360 µmol/L
(2–6 mg/dL)
No No
  1. ACMG = American College of Medical Genetics and Genomics; HPA = hyperphenylalaninemia; PAH = phenylalanine hydroxylase; PKU = phenylketonuria
  2. avan Wegberg et al. [2]
  3. bVockley et al. [3]
  4. cAfter reviewing controversy regarding mixed treatment results with parents