Researchers Uncover Genetic Clue to IBS

Genetics, diet, past trauma, and anxiety have all been thought to play a role in the cause of irritable bowel syndrome (IBS), but new research has found a clue to the disease.

According to the research, published in Gastroenterology, patients with a subset of IBS have a specific genetic defect. The mutation of the SCN5A gene causes bowel function disruption by affecting a sodium channel in the gastrointestinal smooth muscle and pacemaker cells.

While most IBS treatments target common symptoms of the disease like cramping, abdominal pain, bloating gas, diarrhea and constipation, the study could find therapies to treat the condition. Researchers were from the Mayo Clinic and the Karolinska Institutet in Stockholm, as well as Italy and Greece.

“This gives us hope that from only treating symptoms of the disease, we can now work to find disease-modifying agents, which is where we really want to be to affect long-term treatment of IBS,” Gianrico Farrugia, MD, a study author, Mayo Clinic gastroenterologist and director of the Mayo Clinic Center for Individualized Medicine, said in a statement.

Through a study of 584 people with IBS and 1,380 control subjects, the researchers found that 2.2% of IBS patients had a defect in the SCN5A gene. Although, diarrhea-predominant IBS (IBS-D) represented a greater percent of the overall population (25%), the SCN5A mutation was more common in constipation-predominant IBS (IBS-C) patients. Nearly a third (31%) of IBS-C patients had the genetic defect compared to just 10% IBS-D patients.

Researchers were able to restore normalize bowel functions for an IBS-C patient with a defective SCN5A gene through administration of the drug mexiletine, which restored function of the sodium channel Nav1.5 and reversed the patient’s constipation and abdominal pain.

“These findings provide a new pathogenic mechanism for IBS and possible treatment options,” the authors wrote.