Phenylketonuria classification

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief:

Overview

Classification

Subtypes of phenylketonuria

According to Phe levels PKU can be classified as:[1] [2]

  • Mild (mPKU): < 360 μmol/L
  • Moderate (moPKU): 360–1200 μmol/L
  • Classical (cPKU): >1200 μmol/L

Maternal phenylketonuria

Maternal Phenylketonuria (MPKU)[3] is a complication of PKU, caused by the teratogenic effects of high levels of Phe in the fetus. MPKU was first described by Charles Dent in 1956.

Clinical manifestations in the newborn:[4][5]

  • Low weight at birth.
  • Microcephaly.
  • Intellectual disabilities.
  • Congenital heart disease (especially of left heart chambers).
  • Digestive tract deffects.
  • Renal malformations.

Clinical manifestations in the mother:

  • Multiple abortions.

The fetus starts producing PAH hepatic enzyme by the 26th week of pregnancy, before this, the fetus depends on the mother to metabolize the Phe, and if she has a deficiency of PAH, the fetus will double the Phe blood levels of the mother, which is why women with PKU should follow strict diet and treatment before, and during the pregnancy.

  • Ideal levels of Phe during pregnancy: <180 µmol/L
  • Teratogenic and neurotoxic levels of Phe: 360 µmol/L

References

  1. Regnault A, Burlina A, Cunningham A, Bettiol E, Moreau-Stucker F, Benmedjahed K; et al. (2015). "Development and psychometric validation of measures to assess the impact of phenylketonuria and its dietary treatment on patients' and parents' quality of life: the phenylketonuria - quality of life (PKU-QOL) questionnaires". Orphanet J Rare Dis. 10 (1): 59. doi:10.1186/s13023-015-0261-6. PMID 25958326.
  2. Scala I, Concolino D, Casa RD, Nastasi A, Ungaro C, Paladino S; et al. (2015). "Long-term follow-up of patients with phenylketonuria treated with tetrahydrobiopterin: a seven years experience". Orphanet J Rare Dis. 10 (1): 14. doi:10.1186/s13023-015-0227-8. PMC 4351928. PMID 25757997.
  3. Arrieta Blanco F, Bélanger Quintana A, Vázquez Martínez C, Martínez Pardo M (2012). "[Importance of early diagnosis of phenylketonuria in women and control of phenylalanine levels during pregnancy]". Nutr Hosp. 27 (5): 1658–61. doi:10.3305/nh.2012.27.5.5945. PMID 23478721.
  4. Waisbren SE, Rohr F, Anastasoaie V, Brown M, Harris D, Ozonoff A; et al. (2015). "Maternal Phenylketonuria: Long-term Outcomes in Offspring and Post-pregnancy Maternal Characteristics". JIMD Rep. doi:10.1007/8904_2014_365. PMID 25712380.
  5. Didycz B, Domagała L, Pietrzyk JJ (2009). "[The maternal phenylketonuria syndrom--still current problem]". Przegl Lek. 66 (1–2): 4–10. PMID 19485248.