A chromosome 8 gene-cluster polymorphism with low human beta-defensin 2 gene copy number predisposes to Crohn disease of the colon

Research output: Contribution to journalResearch articleContributedpeer-review

Contributors

  • Klaus Fellermann - (Author)
  • Daniel E. Stange - , Department of Visceral, Thoracic and Vascular Surgery, German Cancer Consortium, Partner Site Dresden: German Cancer Research Center (DKFZ), 69120, Heidelberg, Germany. (Author)
  • Elke Schaeffeler - (Author)
  • Hartmut Schmalzl - (Author)
  • Jan Wehkamp - (Author)
  • Charles L. Bevins - (Author)
  • Walter Reinisch - (Author)
  • Alexander Teml - (Author)
  • Matthias Schwab - (Author)
  • Peter Lichter - (Author)
  • Bernhard Radlwimmer - (Author)
  • Eduard F. Stange - (Author)

Abstract

Defensins are endogenous antimicrobial peptides that protect the intestinal mucosa against bacterial invasion. It has been suggested that deficient defensin expression may underlie the chronic inflammation of Crohn disease ( CD). The DNA copy number of the beta-defensin gene cluster on chromosome 8p23.1 is highly polymorphic within the healthy population, which suggests that the defective beta-defensin induction in colonic CD could be due to low beta-defensin gene copy number. Here, we tested this hypothesis, using genomewide DNA copy number profiling by array-based comparative genomic hybridization and quantitative polymerase-chain-reaction analysis of the human beta-defensin 2 (HBD-2) gene. We showed that healthy individuals, as well as patients with ulcerative colitis, have a median of 4 ( range 2 - 10) HBD-2 gene copies per genome. In a surgical cohort with ileal or colonic CD and in a second large cohort with inflammatory bowel diseases, those with ileal resections/disease exhibited a normal median HBD-2 copy number of 4, whereas those with colonic CD had a median of only 3 copies per genome ( for the surgical cohort; P = .008 P = .032 for the second cohort). Overall, the copy number distribution in colonic CD was shifted to lower numbers compared with controls ( for both the surgical cohort and the cohort with inflammatory bowel diseases). Individuals with P = .002 <= 3 copies have a significantly higher risk of developing colonic CD than did individuals with >= 4 copies ( odds ratio 3.06; 95% confidence interval 1.46 - 6.45). An HBD-2 gene copy number of < 4 was associated with diminished mucosal HBD-2 mRNA expression (P = 0.033). In conclusion, a lower HBD-2 gene copy number in the beta-defensin locus predisposes to colonic CD, most likely through diminished beta-defensin expression.

Details

Original languageEnglish
Pages (from-to)439-448
Number of pages10
JournalAmerican journal of human genetics
Volume79
Issue number3
Publication statusPublished - Sept 2006
Peer-reviewedYes

External IDs

PubMed 16909382
Scopus 33748558056

Keywords

Keywords

  • Inflammatory-bowel-disease, Resident intestinal flora, Human genome, Segmental duplications, Ulcerative-colitis, Defensin deficiency, Alpha-defensin, Paneth cells, Dna-sequence, Nod2