The ATG16L1 gene variants rs2241879 and rs2241880 (T300A) are strongly associated with susceptibility to Crohn's disease in the German population.
OBJECTIVE
We analyzed ATG16L1, a recently identified Crohn's disease (CD) susceptibility gene, in a large cohort with inflammatory bowel disease (IBD) including potential interactions with other IBD genes as well as factors regulating its gene expression.


METHODS
Genomic DNA from 2,890 Caucasians including 768 patients with CD, 507 patients with ulcerative colitis (UC), and 1,615 healthy controls was analyzed for 9 different ATG16L1 single nucleotide polymorphisms (SNPs). Genotyping included CARD15/NOD2 variants p.Arg702Trp, p.Gly908Arg, and p.Leu1007fsX1008 and polymorphisms in SLC22A4/OCTN1 (1672 C-->T) and SLC22A5/OCTN2 (-207 G-->C) as well as 10 CD-associated IL23R variants. The transcriptional regulation of ATG16L1 was studied in intestinal epithelial cells following stimulation with Toll-like receptor (TLR) ligands and proinflammatory cytokines and in a murine ileitis model and CD biopsies.


RESULTS
All nine ATG16L1 gene variants analyzed displayed highly significant associations with CD demonstrating a CD-protective effect for the minor allele. The strongest associations were found for rs2241879 and the coding SNP rs2241880 (T300A); P= 3.6 x 10(-6) and 3.7 x 10(-6), respectively (OR 0.74, 95% CI 0.65-0.84 for both variants). The genotype-phenotype analysis revealed no significant associations. In UC, only rs6431660 was weakly disease-associated. There was no evidence for epistasis between the ATG16L1 gene and other susceptibility genes (IL23R, CARD15, SLC22A4/5). ATG16L1 mRNA expression was not upregulated in CD and murine ileitis, and was less than threefold increased in cells stimulated with proinflammatory cytokines and TLR ligands.


CONCLUSIONS
ATG16L1 is a CD susceptibility gene without epistatic interaction with other CD susceptibility genes and is not upregulated in intestinal inflammation.
Glas
Jürgen
J
Department of Medicine II-Grosshadern, University of Munich, Germany.
Konrad
Astrid
A
Schmechel
Silke
S
Dambacher
Julia
J
Seiderer
Julia
J
Schroff
Frieder
F
Wetzke
Martin
M
Roeske
Darina
D
Török
Helga-Paula
HP
Tonenchi
Laurian
L
Pfennig
Simone
S
Haller
Dirk
D
Griga
Thomas
T
Klein
Wolfram
W
Epplen
Jörg T
JT
Folwaczny
Christian
C
Lohse
Peter
P
Göke
Burkhard
B
Ochsenkühn
Thomas
T
Mussack
Thomas
T
Folwaczny
Matthias
M
Müller-Myhsok
Bertram
B
Brand
Stephan
S
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D002648:Child; D003093:Colitis, Ulcerative / Q000235:genetics; D003424:Crohn Disease / Q000235:genetics* / Q000473:pathology; D004843:Epistasis, Genetic; D005260:Female; D015870:Gene Expression; D020022:Genetic Predisposition to Disease; D005838:Genotype; D005858:Germany; D006801:Humans; D007079:Ileitis / Q000235:genetics; D008297:Male; D051379:Mice; D008875:Middle Aged; D053473:Nod2 Signaling Adaptor Protein / Q000235:genetics*; D010641:Phenotype; D020641:Polymorphism, Single Nucleotide
D053473:Nod2 Signaling Adaptor Protein