title: Complex analysis of urate transporters SLC2A9, SLC22A12 and functional characterization of non-synonymous allelic variants of GLUT9 in the Czech population: no evidence of effect on hyperuricemia and gout.
abstract: OBJECTIVE
  Using European descent Czech populations, we performed a study of SLC2A9 and SLC22A12 genes previously identified as being associated with serum uric acid concentrations and gout. This is the first study of the impact of non-synonymous allelic variants on the function of GLUT9 except for patients suffering from renal hypouricemia type 2.
  
  
  METHODS
  The cohort consisted of 250 individuals (150 controls, 54 nonspecific hyperuricemics and 46 primary gout and/or hyperuricemia subjects). We analyzed 13 exons of SLC2A9 (GLUT9 variant 1 and GLUT9 variant 2) and 10 exons of SLC22A12 by PCR amplification and sequenced directly. Allelic variants were prepared and their urate uptake and subcellular localization were studied by Xenopus oocytes expression system. The functional studies were analyzed using the non-parametric Wilcoxon and Kruskall-Wallis tests; the association study used the Fisher exact test and linear regression approach.
  
  
  RESULTS
  We identified a total of 52 sequence variants (12 unpublished). Eight non-synonymous allelic variants were found only in SLC2A9: rs6820230, rs2276961, rs144196049, rs112404957, rs73225891, rs16890979, rs3733591 and rs2280205. None of these variants showed any significant difference in the expression of GLUT9 and in urate transport. In the association study, eight variants showed a possible association with hyperuricemia. However, seven of these were in introns and the one exon located variant, rs7932775, did not show a statistically significant association with serum uric acid concentration.
  
  
  CONCLUSIONS
  Our results did not confirm any effect of SLC22A12 and SLC2A9 variants on serum uric acid concentration. Our complex approach using association analysis together with functional and immunohistochemical characterization of non-synonymous allelic variants did not show any influence on expression, subcellular localization and urate uptake of GLUT9.
authors.affiliation: Institute of Inherited Metabolic Disorders, First Faculty of Medicine, Charles University in Prague and General University Hospital in Prague, Prague, Czech Republic.
authors.forename: Olha
authors.initials: O
authors.lastname: Hurba
authors.affiliation: Charles University in Prague, Faculty of Science, Department of Cell Biology, Prague, Czech Republic.
authors.forename: Andrea
authors.initials: A
authors.lastname: Mancikova
authors.affiliation: Charles University in Prague, Faculty of Science, Department of Cell Biology, Prague, Czech Republic.
authors.forename: Vladimir
authors.initials: V
authors.lastname: Krylov
authors.affiliation: Institute of Inherited Metabolic Disorders, First Faculty of Medicine, Charles University in Prague and General University Hospital in Prague, Prague, Czech Republic.
authors.forename: Marketa
authors.initials: M
authors.lastname: Pavlikova
authors.affiliation: Institute of Rheumatology, Prague, Czech Republic.
authors.forename: Karel
authors.initials: K
authors.lastname: Pavelka
authors.affiliation: Institute of Inherited Metabolic Disorders, First Faculty of Medicine, Charles University in Prague and General University Hospital in Prague, Prague, Czech Republic; Institute of Rheumatology, Prague, Czech Republic.
authors.forename: Blanka
authors.initials: B
authors.lastname: Stibůrková
mesh_terms: D000328:Adult; D000368:Aged; D000483:Alleles; D000818:Animals; D001692:Biological Transport; D016022:Case-Control Studies; D018153:Czech Republic; D005260:Female; D015870:Gene Expression; D005787:Gene Frequency; D051246:Glucose Transport Proteins, Facilitative / Q000235:genetics*; D006073:Gout / Q000235:genetics* / Q000473:pathology; D006801:Humans; D033461:Hyperuricemia / Q000235:genetics* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D027361:Organic Anion Transporters / Q000235:genetics*; D027701:Organic Cation Transport Proteins / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide; D044465:White People
chemical_list: D051246:Glucose Transport Proteins, Facilitative; D027361:Organic Anion Transporters; D027701:Organic Cation Transport Proteins; C491241:SLC22A12 protein, human; C411811:SLC2A9 protein, human