title: Low total antioxidant status is implicated with high 8-hydroxy-2-deoxyguanosine serum concentrations in phenylketonuria.
abstract: BACKGROUND
  Phenylketonuria (PKU), an inborn error of metabolism, is treated with a low phenylalanine (Phe) lifelong diet, which can be characterized as vegetarian. 8-Hydroxy-2-deoxyguanosine (8-OHdG) is highly implicated in degenerative diseases.
  
  
  OBJECTIVE
  To evaluate the effect of plasma total antioxidant status (TAS) and Phe on the serum marker of DNA damage, 8-OHdG, in PKU.
  
  
  METHODS
  Twenty-four PKU patients on a strict diet (group A), 25 PKU patients on a "loose diet" (group B), and 24 healthy children (controls) participated in this study. Plasma TAS was evaluated spectrophotometrically. 8-OHdG and Phe were measured in blood with immunoassays.
  
  
  RESULTS
  TAS levels were significantly higher (P < 0.001) in group A (1458 +/- 140 micromol/L) and controls (1452 +/- 235 micromol/L) than those in group B (907 +/- 150 micromol/L). In contrast, 8-OHdG serum levels were 2-fold higher in group B (0.22 +/- 0.03 ng/mL) as compared with those in group A (0.11 +/- 0.02 ng/mL) and 3-fold higher than those in controls (0.08 +/- 0.02 ng/mL) (P < 0.001). As expected, Phe levels were also significantly higher in group B than those in the other study groups. Positive correlation coefficients were found between Phe and 8-OHdG levels, whereas negative correlations were evaluated between TAS and 8-OHdG in all groups.
  
  
  CONCLUSIONS
  The high Phe and the low TAS plasma levels in PKU patients on a "loose diet" may induce DNA oxidation, as evidenced by the measured high 8-OHdG level in their sera. 8-OHdG evaluation may be a useful marker of increased risk for a neurodegenerative process.
authors.affiliation: Institute of Child Health, Aghia Sophia Children's Hospital, 11527 Athens, Greece.
authors.forename: Kleopatra H
authors.initials: KH
authors.lastname: Schulpis
authors.forename: Stylianos
authors.initials: S
authors.lastname: Tsakiris
authors.forename: Joanne
authors.initials: J
authors.lastname: Traeger-Synodinos
authors.forename: Ioannis
authors.initials: I
authors.lastname: Papassotiriou
mesh_terms: D000080242:8-Hydroxy-2'-Deoxyguanosine; D000975:Antioxidants / Q000032:analysis*; D015415:Biomarkers / Q000097:blood*; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D004249:DNA Damage; D003849:Deoxyguanosine / Q000031:analogs & derivatives* / Q000097:blood*; D004032:Diet; D005260:Female; D006801:Humans; D008297:Male; D010084:Oxidation-Reduction; D010649:Phenylalanine / Q000097:blood; D010661:Phenylketonurias / Q000097:blood* / Q000178:diet therapy; D012307:Risk Factors
chemical_list: D000975:Antioxidants; D015415:Biomarkers; D010649:Phenylalanine; D000080242:8-Hydroxy-2'-Deoxyguanosine; D003849:Deoxyguanosine