Irritable bowel syndrome (IBS) is a common disorder, affecting about 10% (2.5-37%) of the population. Despite its high prevalence, it is biologically poorly understood. Usually, IBS is diagnosed based on the symptomatic profile alone, and on exclusion of other conditions with similar clinical manifestations. Despite evidence for familial clustering, genetic association studies on IBS to-date have not managed to find any genome-wide significant associations, likely owing to the small sample sizes. We propose to undertake the largest genome-wide association study (GWAS) of IBS, using genotype data from the UK Biobank subjects. Misdiagnosis of IBS has been shown to lead to unnecessary surgical procedures, while IBS accounts for over 20% of gastroenterology outpatient work. Results from our study can help to increase our biological understanding of IBS and to identify genetic markers for IBS which could in turn lead to improvements in its diagnosis and treatment. The main analysis will be a genome-wide association study of IBS. Secondary analyses will attempt to find regions of the genome associated with other clinically relevant phenotypes such as age of onset of IBS. A comparative analysis with other traits exhibiting similar symptoms will also be conducted, to identify shared and divergent pathways involved in the diseases. The full cohort will be required.
