title: Correlation of C-reactive protein haplotypes with serum C-reactive protein level and response to anti-tumor necrosis factor therapy in UK rheumatoid arthritis patients: results from the Biologics in Rheumatoid Arthritis Genetics and Genomics Study Syndicate cohort.
abstract: BACKGROUND
  In many European countries, restrictions exist around the prescription of anti-tumor necrosis factor (anti-TNF) treatments for rheumatoid arthritis (RA). Eligibility and response to treatment is assessed by using the disease activity score 28 (DAS28) algorithm, which incorporates one of two inflammatory markers, erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP). Although DAS28-CRP provides a more reliable measure of disease activity, functional variants exist within the CRP gene that affect basal CRP production.
  
  
  METHODS
  DNA samples from the Biologics in Rheumatoid Arthritis Genetics and Genomics Study Syndicate (BRAGGSS) were genotyped for rs1205, rs1800947, and rs3091244 by using either TaqMan or the Sequenom MassARRAY iPLEX system.
  
  
  RESULTS
  Baseline CRP measurements were available for 599 samples with 442 also having data 6 months after treatment with an anti-TNF. For these 442 samples, the study had > 80% power to detect a clinically meaningful difference of 0.6 DAS28 Units for an allele frequency of 5%. Estimated haplotype frequencies corresponded with previous frequencies reported in the literature. Overall, no significant association was observed between any of the markers investigated and baseline CRP levels. Further, CRP haplotypes did not correlate with baseline CRP (P = 0.593), baseline DAS28-CRP (P = 0.540), or change in DAS28-CRP after treatment with an anti-TNF over a 6-month period (P = 0.302).
  
  
  CONCLUSIONS
  Although CRP genotype may influence baseline CRP levels, in patients with very active disease, no such association was found. This suggests that genetic variation at the CRP locus does not influence DAS28-CRP, which may continue to be used in determining eligibility for and response to anti-TNF treatment, without adjusting for CRP genotype.
authors.forename: Darren
authors.initials: D
authors.lastname: Plant
authors.forename: Ibrahim
authors.initials: I
authors.lastname: Ibrahim
authors.forename: Mark
authors.initials: M
authors.lastname: Lunt
authors.forename: Stephen
authors.initials: S
authors.lastname: Eyre
authors.forename: Edward
authors.initials: E
authors.lastname: Flynn
authors.forename: Kimme L
authors.initials: KL
authors.lastname: Hyrich
authors.forename: Ann W
authors.initials: AW
authors.lastname: Morgan
authors.forename: Anthony G
authors.initials: AG
authors.lastname: Wilson
authors.forename: John D
authors.initials: JD
authors.lastname: Isaacs
authors.forename: Anne
authors.initials: A
authors.lastname: Barton
mesh_terms: D000368:Aged; D000465:Algorithms; D018501:Antirheumatic Agents / Q000627:therapeutic use*; D001172:Arthritis, Rheumatoid / Q000097:blood / Q000188:drug therapy* / Q000235:genetics; D001688:Biological Products / Q000627:therapeutic use*; D001799:Blood Sedimentation; D002097:C-Reactive Protein / Q000235:genetics* / Q000378:metabolism*; D015331:Cohort Studies; D005260:Female; D023281:Genomics; D006239:Haplotypes / Q000235:genetics*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010597:Pharmacogenetics; D012720:Severity of Illness Index; D016896:Treatment Outcome; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors*; D006113:United Kingdom
chemical_list: D018501:Antirheumatic Agents; D001688:Biological Products; D014409:Tumor Necrosis Factor-alpha; D002097:C-Reactive Protein