A genome-wide association study on irritable bowl syndrome found several links to certain DNA variants that are only present in women, reports Healio. This is consistent with the disease, which is much more common in women than in men and has been linked to female sex hormones.

Irritable bowel syndrome (IBS) is a condition that affects a person’s digestive system. It is twice as common in women than men, and is thought to affect approximately 10-20% of the population at some point in their lives. Symptoms of IBS are usually related to digestion, and include bloating, cramps, constipation, needing to go to the toilet urgently, and diarrhoea. People are affected differently by IBS, with some having symptoms that flare up occasionally, and others having constant symptoms. The symptoms can be somewhat controlled through special diets and medications. The causes of IBS are unknown, but it has been linked to overactive gut muscles or nerves, stress (half of people with IBS report that flare-ups occur alongside stressful events), food intolerances, and infections that can trigger the disease.

The findings of this study, led by Dr D’Amato, therefore shed light on the relatively unknown causes of IBS. The study examined the genomes of 500,000 participants from the UK Biobank cohort, some of who had IBS and others who were a control group without IBS. The researchers looked at over 7 million single-nucleotide polymorphisms (genetic differences between people). They also analysed approximately 10,000 individuals from Europe and the U.S., and then compared the UK group results to the results from these participants to establish significant findings. The large numbers of participants involved in the study means that the results have a much higher statistical power, and can be considered more likely to be correct.

As a result of this research, several genetic variants suspected to be linked to IBS have been identified. Many of these were particularly linked to women; the non-UK group females showed certain genetic associations with harder stools and constipation-predominant IBS. Furthermore, in the UK group chromosome nine contained genetic variants that were linked to an increased risk of IBS in women. Interestingly, the variants on chromosome nine were in a region that is known to play a role in the age of first menstruation. These results therefore corroborate and extend previous research that suggested a link between female sex hormones and IBS.

These findings provide convincing evidence that genetics play a role in the development of IBS, and further research, for example on the specific genes involved, would develop our understanding of this.

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