title: Prevalence of CARD15/NOD2 mutations in Caucasian healthy people.
abstract: BACKGROUND
  Crohn's disease (CD) has been associated with CARD15/NOD2 mutations in Caucasians. The R702W, G908R, and 1007fs mutations represent 82% of the mutated chromosomes. The relative risk of developing CD in homozygous or compound heterozygous people has been estimated as between 10 and 40 times that of the general population. This high risk may support the opinion that CARD15/NOD2 variants are strong CD risk factors at the individual and population levels.
  
  
  METHODS
  The allele and genotype frequencies were calculated for the R702W, G908R, and 1007fs mutations in 3,575 Caucasian healthy controls recruited by 15 groups distributed on three continents. Geographic homogeneity was tested and the observed proportion of double mutants was compared with the expected value using chi2 tests.
  
  
  RESULTS
  The allele frequencies of the R702W, G908R, and 1007fs mutations were 4.3% (3.6-4.9), 1.2% (0.8-1.6), and 2.3% (1.8-2.8), respectively, with large geographic fluctuations of the G908R, 1007fs, and wild-type alleles (P<0.0001). At the population level, no simple relationship was observed between mutation frequencies and the disease incidences in the studied populations. At the individual level, no significant deficit of double-dose mutation carriers among healthy controls was found, providing strong evidence that the penetrances of the most at-risk genotypes are low.
  
  
  CONCLUSIONS
  Altogether, these data confirm that CARD15/NOD2 acts in interaction with other unknown risk cofactors.
authors.affiliation: INSERM Avenir U763; AP-HP; Université Paris 7, Hôpital Robert Debré, Paris, France.
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Hugot
authors.forename: Isabelle
authors.initials: I
authors.lastname: Zaccaria
authors.forename: Juleen
authors.initials: J
authors.lastname: Cavanaugh
authors.forename: Huiying
authors.initials: H
authors.lastname: Yang
authors.forename: Séverine
authors.initials: S
authors.lastname: Vermeire
authors.forename: Maarit
authors.initials: M
authors.lastname: Lappalainen
authors.forename: Stefan
authors.initials: S
authors.lastname: Schreiber
authors.forename: Vito
authors.initials: V
authors.lastname: Annese
authors.forename: Derek P
authors.initials: DP
authors.lastname: Jewell
authors.forename: Elizabeth V
authors.initials: EV
authors.lastname: Fowler
authors.forename: Steven R
authors.initials: SR
authors.lastname: Brant
authors.forename: Mark S
authors.initials: MS
authors.lastname: Silverberg
authors.forename: Judy
authors.initials: J
authors.lastname: Cho
authors.forename: John D
authors.initials: JD
authors.lastname: Rioux
authors.forename: Jack
authors.initials: J
authors.lastname: Satsangi
authors.forename: Miles
authors.initials: M
authors.lastname: Parkes
mesh_terms: D003424:Crohn Disease / Q000235:genetics; D005060:Europe / Q000453:epidemiology; D005787:Gene Frequency; D006801:Humans; D009154:Mutation; D053473:Nod2 Signaling Adaptor Protein / Q000235:genetics*; D015995:Prevalence; D012307:Risk Factors; D014481:United States / Q000453:epidemiology; D044465:White People
chemical_list: C429018:NOD2 protein, human; D053473:Nod2 Signaling Adaptor Protein