title: Genetic variation in the SLC19A1 gene and methotrexate toxicity in rheumatoid arthritis patients.
abstract: OBJECTIVE
  We investigated the clinical relevance of SLC19A1 genetic variability for methotrexate (MTX) toxicity in rheumatoid arthritis patients using a haplotype-based approach.
  
  
  METHODS
  Two hundred and twelve unrelated rheumatoid arthritis patients and 89 lymphoblastoid cell lines were used to investigate the effect of SLC19A1 SNPs and haplotypes on MTX adverse events and treatment discontinuation.
  
  
  RESULTS
  Two putatively functional SNPs in high linkage disequilibrium, rs1051266 and rs1131596, were associated with protection (hazard ratio: 0.33; 95% CI: 0.16-0.69; adjusted p = 0.021 and hazard ratio: 0.38; 95% CI: 0.17-0.27; adjusted p = 0.021, respectively) of discontinuation of MTX treatment owing to toxicity. These SNPs were also associated with protection from infections. SLC19A1 haplotype analysis found significant associations with MTX discontinuation owing to toxicity (p = 0.025). Quantification of SLC19A1 mRNA in cell lines suggested that rs1131596 was not a major causal variant.
  
  
  CONCLUSIONS
  Individual SNP and haplotype analyses suggest that rs1051266 could be a functional variant altering MTX toxicity; however, validation in independent studies is needed.
authors.affiliation: Pharmacogenetics Laboratory, Institute of Biochemistry, University of Ljubljana, Vrazov trg 2, 1000 Ljubljana, Slovenia.
authors.forename: Petra
authors.initials: P
authors.lastname: Bohanec Grabar
authors.forename: Luis J
authors.initials: LJ
authors.lastname: Leandro-García
authors.forename: Lucía
authors.initials: L
authors.lastname: Inglada-Pérez
authors.forename: Dušan
authors.initials: D
authors.lastname: Logar
authors.forename: Cristina
authors.initials: C
authors.lastname: Rodríguez-Antona
authors.forename: Vita
authors.initials: V
authors.lastname: Dolžan
mesh_terms: D000368:Aged; D018501:Antirheumatic Agents / Q000008:administration & dosage / Q000633:toxicity; D001172:Arthritis, Rheumatoid / Q000188:drug therapy* / Q000235:genetics; D054316:Biomarkers, Pharmacological; D002460:Cell Line; D005260:Female; D056726:Genetic Association Studies; D006239:Haplotypes; D006801:Humans; D015810:Linkage Disequilibrium; D008297:Male; D008727:Methotrexate / Q000008:administration & dosage / Q000633:toxicity; D008875:Middle Aged; D020641:Polymorphism, Single Nucleotide; D058978:Reduced Folate Carrier Protein / Q000235:genetics*
chemical_list: D018501:Antirheumatic Agents; D054316:Biomarkers, Pharmacological; D058978:Reduced Folate Carrier Protein; C548699:SLC19A1 protein, human; D008727:Methotrexate