title: Incidence of Mycobacterium avium subspecies paratuberculosis in a population-based cohort of patients with Crohn's disease and control subjects.
abstract: OBJECTIVE
  To define the incidence of Mycobacterium avium subspecies paratuberculosis (MAP) in patients with Crohn's disease (CD) and in control subjects.
  
  
  METHODS
  Blood samples from 361 CD patients from a previously described population-based inflammatory bowel disease (IBD) cohort and 200 blood donor controls, of known NOD2 genotype, were screened by PCR for MAP-specific IS900 DNA. These results were correlated with NOD2 genotype.
  
  
  RESULTS
  The PCR assay was capable of detecting 20 fg of purified MAP DNA, equivalent to roughly 100 MAP cells/mL of blood. MAP-specific IS900 DNA was detected in 33.8% of CD cases and 21.5% of controls (OR 1.86, 95% CI 1.247-2.785, P= 0.002). All study participants were genotyped for the NOD2 mutations 2104C>T (R702W), 2722G>C (G908R), and 3020insC (1007fs). Carriage of one or two NOD2 mutations was not associated with a significantly higher risk of CD (OR 0.75, 95% CI 0.465-1.207, P= 0.234). No significant association was seen in the CD cohort for carriage of one or two NOD2 mutations and MAP status (OR 0.883, 95% CI 0.494-1.579, P= 0.675).
  
  
  CONCLUSIONS
  Screening peripheral blood using IS900 PCR indicated that MAP DNA could be detected in a significant proportion of CD cases from a large population-based cohort, and also, in control subjects. The over-representation of MAP DNA in CD suggests either a role or a probable role for MAP in the etiology of CD.
authors: Department of Pathology, University of Otago, Christchurch, New Zealand.
authors: Robert W
authors: RW
authors: Bentley
authors: Jacqui I
authors: JI
authors: Keenan
authors: Richard B
authors: RB
authors: Gearry
authors: Martin A
authors: MA
authors: Kennedy
authors: Murray L
authors: ML
authors: Barclay
authors: Rebecca L
authors: RL
authors: Roberts
mesh_terms: D015331:Cohort Studies; D003424:Crohn Disease / Q000453:epidemiology* / Q000235:genetics; D003430:Cross-Sectional Studies; D004269:DNA, Bacterial / Q000235:genetics; D005838:Genotype; D006801:Humans; D015994:Incidence; D008403:Mass Screening; D016927:Mycobacterium avium subsp. paratuberculosis / Q000235:genetics; D009520:New Zealand; D053473:Nod2 Signaling Adaptor Protein; D010283:Paratuberculosis / Q000453:epidemiology*; D016133:Polymerase Chain Reaction; D012680:Sensitivity and Specificity
chemical_list: D004269:DNA, Bacterial; C429018:NOD2 protein, human; D053473:Nod2 Signaling Adaptor Protein