A new study reported in Nature Communications has confirmed that some small changes in certain genes in the human genome can increase the risk of gastrointestinal diseases like ulcers, irritable bowel disorder, and inflammatory bowel disease. This genome-wide association study analyzed genetic data from over 450,000 people in the UK Biobank. It showed that variants in genes that are involved in: the release of gastric acids, ability to counteract damage caused by infection, and movement in the gastrointestinal system are connected to susceptibility to Helicobacter pylori infection, which can lead to ulcers.
"To identify why some people develop ulcers, we studied health data from 456,327 individuals from the UK Biobank and identified eight genetic variations associated with the risk of getting peptic ulcer disease," said study co-author Professor Naomi Wray of the University of Queensland's Institute for Molecular Bioscience (IMB). "Six of the eight variations can be linked to why some people are more prone to H. pylori infection, which would make them more susceptible to peptic ulcer disease."
The researchers also found a genetic connection between gastrointestinal disorders and depression. Similar genetic variants are involved in both disorders. While the scientists found that there was a significant increase in the risk of the four digestion disorders along with depression, it was unclear whether that risk is causal. Some patients with both conditions may be feeling the side effects of anti-depressants, which are known to cause changes in the gut, for example; or gut distress may cause depression simply because it impairs a person's social function so much, which may lead to isolation that causes sadness and depression. More work will be needed to decipher these connections.
This study shows that these complex disorders may arise from a complex interplay of factors. It was once thought that stress caused ulcers, until H. pylori infections were found to be involved. While medication can treat the disorder, this work suggests that psychological factors can't be written off completely as a potential contributing cause.
Professor Wray noted that one peptic ulcer treatment is targeted to a gene variation. Learning more about other genetic variants that are contributing to the risk could develop more treatments.
"Access to vast health and genomic data sets allows researchers to advance understanding of many complex diseases and traits," Wray said. "Resources such as the UK Biobank have made it possible to now study the genetic contribution to common diseases, such as peptic ulcer disease, and understand the risks more fully. If we can provide genetic risk scores to patients, it could be part of a prevention program to help reduce the rates of peptic ulcer disease."
"As a medical student, I noticed how some patients' gastrointestinal symptoms improved after psychotherapy or psychiatry treatment," added study co-author Dr. Yeda Wu of IMB. "This study linking major depression with an increased risk of gastrointestinal disorders also explains the co-morbidity of the conditions."
Wu noted that this work also supports a holistic treatment approach to treating patients with gastrointestinal disease patients.