While it is common for IBS patients to have relatives who suffer from similar symptoms, the hereditability of IBS has not yet been confirmed. The development of IBS among relatives is rather believed to be due to exposure to similar environmental factors in the shared household. Exposure to household stressors during early childhood is associated with an increased risk of developing IBS symptoms. Examples of stressors are physical and verbal abuse, poor living conditions, ill family members, etc. [1.]
Why is exposure to stressors a risk factor?
Stress is known to alter the composition and growth of gut microbiota, and trigger the release of cortisol – a hormone mediating stress response. Prolonged exposure to various stressors can have a negative effect on the gut-brain axis. That is why stress is often believed to be one of the sources of gastrointestinal problems.
IBS could be caused by a genetic mutation
It was however possible to identify a genetic mutation in the SCN5A gene. This mutation affects sodium channels in the gastrointestinal smooth muscle. Sodium channels contribute to normal intestinal motility – the movement of food through the intestines. A defect in these channels causes IBS patients to have a disrupted bowel movement. This mutation has so far been found to be common in about 2-3% of IBS patients. [2.]
There are however genetic disorders that mimic the symptoms of IBS. The most common include inflammatory bowel disease, Crohn’s disease, or Celiac disease. It is important to rule out these diagnoses to find the right treatment.
Is it common to have IBS and an inherited psychiatric disorder?
It is also worth considering the genetics of psychiatric disorders which are often associated with IBS symptoms. In some patients with IBS, treatment with antidepressants was found to be effective in reducing the severity of the symptoms. It is not clear why it works but patients with a history of traumatic events and IBS patients with subtype-D were more likely to respond to the treatment. [3.]
Please note that antidepressants are often associated with adverse side effects and the other treatment types should be considered before opting for treatment with antidepressants.
Summary
The heritability of IBS has not yet been confirmed. IBS symptoms among relatives are most likely due to shared experiences.
Genetic mutation was found in the gene coding for sodium channels that causes intestinal motility to function irregularly. It is estimated that only about 2-3% of IBS patients have this mutation.
The risk of developing IBS symptoms is greater in patients with inherited psychiatric disorders. Antidepressants could be an effective treatment of IBS symptoms in certain cases.
References
- Saito, Y. A. (2011). The Role of Genetics in IBS. Gastroenterology Clinics of North America, 40(1), 45–67. https://doi.org/10.1016/j.gtc.2010.12.011
- Genetic clue to irritable bowel syndrome found. (2014). ScienceDaily. https://www.sciencedaily.com/releases/2014/03/140320173158.htm
- Quigley, E., Craig, O., & Dinan, T. (2011). The role of antidepressants in the management of irritable bowel syndrome (IBS) [Review of The role of antidepressants in the management of irritable bowel syndrome (IBS)]. Medicine, Psychology, 26(2), 140–146.
