Genetic Link to IBS Identified in Women

Irritable bowel syndrome is the most common gastrointestinal disorder. More than 10% of the population suffers from recurrent symptoms including abdominal pain, gas, diarrhea and constipation and it is more common in women than men.

A new study links certain DNA variants to increased risk of irritable bowel syndrome (IBS) in women. The findings might help explain why IBS is more common in women than in men. The study has identified DNA variants that are associated with increased risk of IBS, but only in women.

A large team of international scientists led by the Karolinska Institutet (Stockholm, Sweden) performed a genome-wide association study (GWAS) of the large UK Biobank population-based cohort, which includes genotype and health data from 500,000 participants. By following up this result in 2,045 patients from IBS expert centers in Sweden, Belgium, the Netherlands, Italy and the USA, the investigators observed further associations with constipation-predominant IBS as well as harder stools, again only in women.

The scientists identified a genome-wide significant association on chromosome 9q31.2 (SNP rs10512344), in a region previously linked to age at menarche, and 13 additional loci of suggestive significance. Sex-stratified analyses revealed that the variants at 9q32.1 affect risk of IBS in only women and also associate with constipation-predominant IBS in women and harder stools in women in the population-based sample. Functional annotation of the 9q32.1 locus identified eight candidate genes, including the elongator complex protein 1 gene (ELP1 or IKBKAP), which is mutated in patients with familial dysautonomia.

Mauro D'Amato, PhD, an Associate Professor of Molecular Genetics and senior author of the study, said, “Exploiting the large UK Biobank resource, as well as several patient cohorts from European and USA expert centers, we have been able to study genetic predisposition to IBS with increased statistical power, better than ever before. Although we cannot point to individual genes at this early stage, we believe these results are exciting, as they converge with existing data on female preponderance and a role of sex-hormones in IBS.” The study was published on April 4, 2018, in the journal Gastroenterology.

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