title: Associations of allelic variants of the multidrug resistance gene (ABCB1 or MDR1) and inflammatory bowel disease and their effects on disease behavior: a case-control and meta-analysis study.
abstract: BACKGROUND
  Allelic variants of the ATP-binding cassette, subfamily B member 1 (ABCB1), also known as the multidrug resistance gene (MDR1) that encodes the membrane-bound efflux transporter P-glycoprotein 170 (PGP-170), have been associated with inflammatory bowel disease but with conflicting results.
  
  
  METHODS
  The present study examined the association of ABCB1 C3435T and G2677T/A in a large British case-control cohort of 828 Crohn's disease, 580 ulcerative colitis (UC) cases, and 285 healthy controls. The effect of these variants was further examined with respect to phenotypic and epidemiological characteristics. A meta-analysis was carried out of our results and those from 8 previously published association studies of the C3435T variant in inflammatory bowel disease.
  
  
  RESULTS
  The 2677T allele was significantly increased in British UC cases compared with controls (45.2% vs. 39.6%; P = 0.034). In particular, the TT genotype was significantly associated with severe UC (odds ratio [OR] 1.90; 95% CI 1.01-3.55) and the use of steroids in UC (OR 1.77; 95% CI 1.08-2.88). No significant association was seen with C3435T and UC, Crohn's disease, or any clinical subgroup. A meta-analysis of 9 association studies of C3435T showed a significant association of the 3435T allele with UC (OR 1.12; 95% CI 1.02-1.23; P = 0.013) but not with CD.
  
  
  CONCLUSIONS
  These results indicate that ABCB1 sequence variants are associated with a small increase in the risk of developing UC and may influence disease behavior.
authors.affiliation: Department of Medical and Molecular Genetics, King's College London School of Medicine, Guy's Hospital, UK.
authors.forename: Clive M
authors.initials: CM
authors.lastname: Onnie
authors.forename: Sheila A
authors.initials: SA
authors.lastname: Fisher
authors.forename: Reenal
authors.initials: R
authors.lastname: Pattni
authors.forename: Jeremy
authors.initials: J
authors.lastname: Sanderson
authors.forename: Alastair
authors.initials: A
authors.lastname: Forbes
authors.forename: Cathryn M
authors.initials: CM
authors.lastname: Lewis
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Mathew
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics*; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000483:Alleles; D002648:Child; D002675:Child, Preschool; D004247:DNA / Q000235:genetics*; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D005787:Gene Frequency; D005838:Genotype; D006801:Humans; D015212:Inflammatory Bowel Diseases / Q000235:genetics / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D027361:Organic Anion Transporters / Q000235:genetics*; D011110:Polymorphism, Genetic; D012189:Retrospective Studies
chemical_list: C513055:ABCB1 protein, human; D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D027361:Organic Anion Transporters; D004247:DNA