A new Danish study investigating the genetics behind inflammatory bowel disease (IBD) found that variants of inflammatory genes TLR1 and IL12B are associated with an increased risk of developing the disease. The team also found that a variant of the IL18 gene was associated with a lower risk of IBD.
The study, named "Polymorphisms in the Toll-Like Receptor and the IL-23/IL-17 Pathways Were Associated with Susceptibility to Inflammatory Bowel Disease in a Danish Cohort", was performed by Steffen Bank and colleagues from Viborg Regional Hospital, Denmark in collaboration with a large number of Danish clinics and institutions. The article was published in the journal PLOS ONE in December 2015.
Enrolling 624 patients with Crohn's disease (CD), 411 with ulcerative colitis (UC), and 795 controls, the team employed what is known as a candidate gene approach. Genes that are theoretically involved in a disease are screened for mutations (often using known mutations present in databases), and the team then explores if the gene variants are found more often in patients than in controls.
The team reported that when they looked separately at the different patient groups, they could see that variants of the inflammatory genes TLR1, TLR5, and IL12B were associated with an increased risk of CD, while in the UC group they only observed an association with TLR1. In both groups, the team found that IL18 was associated with a decreased risk.