OBJECTIVES: To determine whether genetic polymorphisms within the folate pathway are associated with red blood cell (RBC) methotrexate (MTX) polyglutamate concentrations, RBC folate concentrations and MTX efficacy/toxicity. METHODS: Disease activity in 200 rheumatoid arthritis patients on MTX was assessed by swollen and tender joint counts and Disease Activity Score 28. Genetic polymorphisms shown to have an effect on gene expression or protein function were examined. RESULTS: RBC folate concentrations were significantly associated with MTHFR 677C>T (P=0.002), MTRR 66A>G (P<0.0001), MTHFD1 1958G>A (P=0.001) and SHMT 1420C>T (P=0.012), whereas no association of these polymorphisms with disease activity was observed. None of the polymorphisms tested predicted RBC MTX polyglutamate concentrations. There were weak associations between central nervous system adverse effects and AMPD1 34C>T (P=0.04) and between gastrointestinal adverse effects and MTHFD1 1958G>A (P=0.03) and ABCC2 IVS23+56T>C (P=0.045). There was a stronger association between any adverse effect and ABCG2 914C>A (P=0.004). CONCLUSION: Although RBC folate concentrations are associated with genetic polymorphisms within the folate pathway, these variants do not predict disease activity. To accurately evaluate whether any polymorphisms are reliable predictors of MTX efficacy or toxicity, large prospective clinical trials are required. Furthermore, application of a genome-wide association strategy is likely to uncover novel predictors of MTX response.
OBJECTIVES: To determine whether genetic polymorphisms within the folate pathway are associated with red blood cell (RBC) methotrexate (MTX) polyglutamate concentrations, RBC folate concentrations and MTX efficacy/toxicity. METHODS: Disease activity in 200 rheumatoid arthritispatients on MTX was assessed by swollen and tender joint counts and Disease Activity Score 28. Genetic polymorphisms shown to have an effect on gene expression or protein function were examined. RESULTS: RBC folate concentrations were significantly associated with MTHFR 677C>T (P=0.002), MTRR 66A>G (P<0.0001), MTHFD1 1958G>A (P=0.001) and SHMT 1420C>T (P=0.012), whereas no association of these polymorphisms with disease activity was observed. None of the polymorphisms tested predicted RBC MTX polyglutamate concentrations. There were weak associations between central nervous system adverse effects and AMPD1 34C>T (P=0.04) and between gastrointestinal adverse effects and MTHFD1 1958G>A (P=0.03) and ABCC2 IVS23+56T>C (P=0.045). There was a stronger association between any adverse effect and ABCG2 914C>A (P=0.004). CONCLUSION: Although RBC folate concentrations are associated with genetic polymorphisms within the folate pathway, these variants do not predict disease activity. To accurately evaluate whether any polymorphisms are reliable predictors of MTX efficacy or toxicity, large prospective clinical trials are required. Furthermore, application of a genome-wide association strategy is likely to uncover novel predictors of MTX response.
Authors: Torben S Mikkelsen; Caroline F Thorn; Jun J Yang; Cornelia M Ulrich; Deborah French; Gianluigi Zaza; Henry M Dunnenberger; Sharon Marsh; Howard L McLeod; Kathy Giacomini; Mara L Becker; Roger Gaedigk; James Steven Leeder; Leo Kager; Mary V Relling; William Evans; Teri E Klein; Russ B Altman Journal: Pharmacogenet Genomics Date: 2011-10 Impact factor: 2.089
Authors: L A Davis; B Polk; A Mann; R K Wolff; G S Kerr; A M Reimold; G W Cannon; T R Mikuls; L Caplan Journal: Clin Exp Rheumatol Date: 2014-01-20 Impact factor: 4.473
Authors: Dong-Yang Liu; Hoi-Kei Lon; Yan-Lin Wang; Debra C DuBois; Richard R Almon; William J Jusko Journal: Biopharm Drug Dispos Date: 2013-04-07 Impact factor: 1.627
Authors: Lisa K Stamp; Jody Hazlett; Rebecca L Roberts; Christopher Frampton; John Highton; Paul A Hessian Journal: Arthritis Res Ther Date: 2012-06-08 Impact factor: 5.156