Researchers estimate that approximately 15 to 20 per cent of the Western world has IBS, a common disorder that affects the large intestine.
Most patients with the disorder commonly experience symptoms of cramping, abdominal pain, bloating gas, diarrhoea and constipation. Most treatments for IBS target these symptoms.
Researchers found that patients with a subset of IBS have a specific genetic defect, a mutation of the SCN5A gene.
This defect causes patients to have a disruption in bowel function, by affecting the Nav1.5 channel, a sodium channel in the gastrointestinal smooth muscle and pacemaker cells.
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"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," said Gianrico Farrugia, a study author, Mayo Clinic gastroenterologist and director of the Mayo Clinic Center for Individualised Medicine.
Researchers studied the sodium channel of 584 people with IBS and 1,380 control subjects. The analysis demonstrated that a defect in the SCN5A gene was found in 2.2 per cent of IBS patients.
Additionally, researchers were able to restore function to a patient with constipation predominant IBS with a defective SCN5A gene and resulting abnormally functioning sodium channel.
Researchers used a drug called mexiletine, which restored the function of the channel and reversed the patient's symptoms of constipation and abdominal pain.
The study was published in the journal Gastroenterology.