Phenylketonuria E70.00

Fölling, 1934; Jervis, 1953; Morgan 1786;

Worldwide spread. Most common genetic defect of amino acid metabolism. Incidence (Germany): 1/5.000-16.000 births. More frequent in the population of Turkish origin (especially due to the increased incidence of consanguine marriages).

Autososomal recessive inherited enzyme defect due to mutations of the phenylalanine hydroxylase gene(PAH gene; gene locus: 12q24.1) with consecutive reduction or complete absence of phenylalanine hydroxylase and resulting tyrosine deficiency in the blood and internal organs. L-phenylalanine ingested with food cannot be hydroxylated correctly in the para position, so that no L-tyrosine can be formed from phenylalanine. In this case, L-tyrosine must be supplied to the body. In phenylketonuria, >1000 mutations in the PAH gene have been detected to date. There are considerable regional differences in the spectrum of mutations.

Integument: Light skin, light blond hair, blue eyes (lack of tyrosine leads to reduced melanin synthesis). Sensitivity to light, hyperhidrosis with a mouse-like odor. Dry, pityriasiform reed skin. In 20-50% of cases symptoms of atopic eczema.

Extracutaneous manifestations: among others oligophrenia, seizures.

Skin changes: Skin care with oily external agents (e.g. base cream (DAC), ash base ointment, linola cream). Oil baths such as Balneum Hermal F, Linola Fett N oil bath.

Start early with a diet low in phenylalanine! Purchase of suitable food from pharmacies and hospitals. Manufacturer: e.g. SHS-Gesellschaft für klinische Ernährung mbH, Happenbacher Str. 5, 74074 Heilbronn, P.O. Box 3061.

1. Acosta PB et al (2003) Nutrient intakes and physical growth of children with phenylketonuria undergoing nutrition therapy. J Am Diet Assoc 103: 1167-1173
2. Fölling A (1934) On the excretion of phenylpyruvic acid in the urine as a metabolic abnormality in combination with imbecillization. Hoppe-Seylers Z Physiol Chem 227: 169-176
3. Jervis GA (1953) Phenylpyruvic oligophrenia deficiency of phenylalanine-oxidizing system. Proc Soc Exper Biol Med 82: 514-515
4. Jervis GA (1955) Studies on phenylpyruvic oligophrenia: the position of the metabolic error. J Biol Chem 169: 651-656
5. Meli C et al (2002) Dietary control of phenylketonuria. Lancet 360: 2075-2076
6. Muntau AC (2002) Tetrahydrobiopterin as an alternative treatment for mild phenylketonuria. N Engl J Med 347: 2122-2132
7. Walter JH et al (2002) How practical are recommendations for dietary control in phenylketonuria? Lancet 360: 55-57
8. Wilcken B et al (2003) Screening newborns for inborn errors of metabolism by tandem mass spectrometry. N Engl J Med 348: 2304-2312