Pooled Sequencing of 531 Genes in Inflammatory Bowel Disease Identifies an Associated Rare Variant in BTNL2 and Implicates Other Immune Related Genes

Author Summary Crohn's disease and ulcerative colitis are two forms of inflammatory bowel disease which cause chronic inflammation of the gastrointestinal tract. Common genetic variants in more than 160 regions of the human genome have been associated with an altered risk of these disorders, but leave much of the estimated genetic contribution to disease risk unexplained. We sought to establish whether rare genetic variants which alter the structure or function of the proteins encoded by genes also contribute to disease susceptibility. We used high throughput DNA sequencing to screen over 500 genes for such variants in nearly 500 patients and controls, and validated interesting variants in about 10,000 patients and 7,000 controls. We detected association of a limited number of rare variants from coding regions with disease, suggesting that they do not account for a large proportion of genetic susceptibility. However, they highlight the involvement of genes of potential importance in the development of inflammatory bowel disease, including those involved in the activation of immune cells, the regulation of immune response genes, and the degradation of proteins in cells.