What are the roles of the genes ITLN1, ATG16L1, IRGM, and PTGER4 in the etiology of Crohn disease?

Updated: Jul 26, 2019
  • Author: Leyla J Ghazi, MD; Chief Editor: Praveen K Roy, MD, AGAF  more...
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Answer

The interlectin gene (ITLN1) is expressed in the small bowel and colon and is involved in recognition of certain microorganisms in the intestine. Other GWASs found associations between susceptibility to Crohn disease and polymorphisms in genes associated with the intestinal milieu. One study, involving nearly 20,000 SNPs in 735 individuals with Crohn disease, found an association in the ATG16L1 gene, which encodes the autophagy-related 16-like protein involved in the autophagosome pathway that processes intracellular bacteria. [19, 20]

SNPs in other autophagy genes have also been associated with susceptibility to Crohn disease, as in one study examining at 2 polymorphisms that flanked the IRGM gene and that may be in the regulatory material for the gene. [21] Subsequently, various other loci have been implicated in the autophagy pathway as being associated with Crohn disease, with mounting evidence that the autophagosome pathway is very important in the pathogenesis of the disease.

Studies have also provided strong support for IBD susceptibility genes on chromosome 5p13.1, which is a gene desert but does modulate expression of the PTGER4 gene. A murine PTGER4 knockout model has been studied and found to exhibit significant susceptibility to severe colitis. [22]


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