title: Evaluation of polymorphisms in the sulfonamide detoxification genes CYB5A and CYB5R3 in dogs with sulfonamide hypersensitivity.
abstract: BACKGROUND
  Delayed hypersensitivity (HS) reactions to potentiated sulfonamide antimicrobials occur in both dogs and humans, and involve an intermediate hydroxylamine metabolite that is detoxified by cytochrome b(5) and NADH cytochrome b(5) reductase.
  
  
  OBJECTIVE
  We hypothesized that polymorphisms in the genes (CYB5A and CYB5R3) encoding these 2 enzymes would be associated with risk of sulfonamide HS in dogs.
  
  
  METHODS
  A total of 18 dogs with delayed HS to potentiated sulfonamide antimicrobials and 16 dogs that tolerated (TOL) a therapeutic course of these drugs without adverse effect.
  
  
  METHODS
  CYB5A and CYB5R3 were sequenced from canine liver, and the promoter, exons, and 3' untranslated regions of both genes were resequenced from genomic DNA obtained from all dogs.
  
  
  RESULTS
  Multiple polymorphisms were found in both genes. When controlled for multiple comparisons, the 729GG variant in CYB5R3 was significantly overrepresented in dogs with sulfonamide HS (78% of dogs), compared to TOL dogs (31%; P = .003).
  
  
  CONCLUSIONS
  The CYB5R3 729GG variant may contribute to the risk of sulfonamide HS in dogs. Functional characterization of this polymorphism, as well as genotyping in a larger number of HS and TOL dogs, is warranted.
authors: Department of Medical Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI 53706-1102, USA.
authors: J
authors: J
authors: Funk-Keenan
authors: J
authors: J
authors: Sacco
authors: Y Y Amos
authors: YY
authors: Wong
authors: S
authors: S
authors: Rasmussen
authors: A
authors: A
authors: Motsinger-Reif
authors: L A
authors: LA
authors: Trepanier
mesh_terms: D000818:Animals; D042966:Cytochrome-B(5) Reductase / Q000235:genetics* / Q000276:immunology; D015786:Cytochromes b5 / Q000235:genetics* / Q000276:immunology; D004283:Dog Diseases / Q000235:genetics* / Q000276:immunology; D004285:Dogs; D004342:Drug Hypersensitivity / Q000209:etiology / Q000235:genetics / Q000276:immunology / Q000662:veterinary*; D005260:Female; D005838:Genotype; D008099:Liver / Q000201:enzymology / Q000276:immunology; D008297:Male; D011110:Polymorphism, Genetic; D012313:RNA / Q000737:chemistry / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000662:veterinary; D013449:Sulfonamides / Q000009:adverse effects*
chemical_list: D013449:Sulfonamides; D012313:RNA; D015786:Cytochromes b5; D042966:Cytochrome-B(5) Reductase