title: Vitamin C levels in blood are influenced by polymorphisms in glutathione S-transferases.
abstract: OBJECTIVE
  Glutathione S-transferases (GSTs) are intimately involved in combating oxidative stress and in detoxifying xenobiotics. Our objective was to examine possible interactions between polymorphisms in GST genes and plasma vitamin C, tocopherols and carotenoids in 149 reference subjects and 239 subjects occupationally exposed to mineral fibres (asbestos, rock wool, glass fibre), agents that induce oxidative stress.
  
  
  METHODS
  Deletion of GSTM1 and GSTT1, and substitution 105Ile/Val in GSTP1 genes were determined by PCR, antioxidants in plasma were measured by HPLC.
  
  
  RESULTS
  Tocopherols and carotenoids were affected by age, sex, smoking, occupational exposure to fibres, but not by GST polymorphisms. Vitamin C level was influenced by sex, smoking and occupational exposure. Subjects with deletion of GST had lower vitamin C levels compared with subjects carrying the functional gene variant. Vitamin C levels varied according to GSTM1 polymorphism in the whole group (p < 0.05), in all reference subjects (p < 0.05), in the asbestos factory reference group (p < 0.05), and according to GSTT1 polymorphism in reference group of the rock wool plant (p < 0.05). Vitamin C levels were approximately 20% lower in subjects with both functionally deficient genes in the whole group (p < 0.01) and in all non-exposed subjects (p < 0.05).
  
  
  CONCLUSIONS
  The correspondence of lower vitamin C levels with non-functional GST isoenzymes may indicate a causal connection between two antioxidant defence pathways, also the underlying mechanism is not yet clear. It seems that supplementation by natural antioxidants is particularly important for subjects with unfavourable genetic makeup and in those exposed to oxidative stress.
authors.affiliation: Department of Experimental and Applied Genetics, Slovak Medical University, Limbova 12, 833 03 Bratislava, Slovakia.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Horska
authors.forename: Csilla
authors.initials: C
authors.lastname: Mislanova
authors.forename: Stefano
authors.initials: S
authors.lastname: Bonassi
authors.forename: Marcello
authors.initials: M
authors.lastname: Ceppi
authors.forename: Katarina
authors.initials: K
authors.lastname: Volkovova
authors.forename: Maria
authors.initials: M
authors.lastname: Dusinska
mesh_terms: D000328:Adult; D001194:Asbestos / Q000633:toxicity; D001205:Ascorbic Acid / Q000097:blood*; D002338:Carotenoids / Q000097:blood; D005260:Female; D017353:Gene Deletion; D056726:Genetic Association Studies; D014644:Genetic Variation; D005898:Glass; D051549:Glutathione S-Transferase pi / Q000235:genetics*; D005982:Glutathione Transferase / Q000172:deficiency / Q000235:genetics*; D006801:Humans; D008297:Male; D008875:Middle Aged; D019016:Mineral Fibers / Q000633:toxicity; D016273:Occupational Exposure; D018384:Oxidative Stress / Q000187:drug effects*; D020641:Polymorphism, Single Nucleotide; D018154:Slovakia; D024505:Tocopherols / Q000097:blood
chemical_list: D001194:Asbestos; D001205:Ascorbic Acid; D002338:Carotenoids; D051549:Glutathione S-Transferase pi; D005982:Glutathione Transferase; D019016:Mineral Fibers; D024505:Tocopherols; C009753:fiberglass; C413545:glutathione S-transferase T1