Is inflammatory bowel disease hereditary?

The question of whether inflammatory bowel disease (IBD) is hereditary is complex and has been the subject of numerous scientific investigations.

Neither Crohn’s disease or ulcerative colitis are hereditary pathologies, although studies have demonstrated that there is a genetic predisposition for their development.

These studies have identified certain genetic markers that can increase a person’s susceptibility to symptomatically manifest these diseases. However, having a family history does not mean that the disease will develop, since many individuals who suffer from IBD do not have relatives living with these pathologies.

What is the origin of IBD and how does it manifest?

In order to answer this question it is necessary to talk about the interaction of different factors: genetic predisposition, the environment, the immune response and the intestinal microbiota of each person.

The combination of these elements can provoke a disordered inflammatory response that ends up attacking the patient’s own tissue. This medical condition, both in ulcerative colitis and Crohn’s disease, usually manifests with symptoms such as diarrhoea, rectal bleeding, abdominal pain, fatigue and weight loss among others. In this Mayo Clinic⁴ video they explain very well, and in a simple and visual way, what happens in the body:

What are the environmental factors or elements that can trigger IBD?

IBD is a consequence of the inadequate response of our immune system towards our own body. Although the origin is unknown and we know that there is also a genetic predisposition that could favour the manifestation of these diseases, we also know that there are some environmental factors that condition or trigger these immune disorders in individuals more prone or susceptible to develop an exaggerated immune response to these factors.

According to EFCCA, these environmental conditions may include:

• diet
• certain infections
• exposure to tobacco smoke
• treatment with antibiotics, oral contraceptives or non-steroidal anti-inflammatory drugs)

Also, according to this study², it is believed that the influence of environmental factors explains the increase in incidence in recent decades in industrialised countries, which is not attributable to genetic modifications. This fact is highlighted by the increase in cases among immigrants from developing countries, especially when they migrate to developed countries before the age of 15 years.

In summary, although there is a genetic influence in the predisposition to suffer from IBD, we cannot consider these diseases to be hereditary. Having relatives with IBD may increase the risk, but the presence of environmental factors, immune health and the patient’s intestinal microbiota also play a significant role in the manifestation of the disease.

Thus, as has been published in some articles³, it is important to recognise that the study of the pathogenesis of IBD has advanced tremendously in recent years, coinciding with advances in genetic testing techniques and computer analysis tools. Large amounts of information can be obtained from genetic profiles, microbiome composition, etc. In the future, techniques will be required to analyse these data and even to know the disease mechanisms specific to each individual. It is expected that we will be able to obtain the genetic profile of a patient with IBD, predict their clinical course and even predict the response to certain therapies in order to choose the most appropriate one for each patient.

1. https://educainflamatoria.com/crohn-cat/causas-y-factores-de-influencia-crohn/
2. Enrique Medina: Enfermedad inflamatoria intestinal (I): clasificación, etiología y clínica, An Pediatr Contin. 2013;11(2):59-67
3. Felipe Silva, Tomás Gaticab, Carolina Pavez: Etiología y fisiopatología de la enfermedad inflamatoria intestinal ,REV. MED. CLIN. CONDES – 2019; 30(4) 262-272
4. 14. Santos MPC, Gomes C, Torres J. Familial and ethnic risk in inflammatory bowel disease. Ann Gastroenterol. 2018;31(1):14–23.
5. https://www.youtube.com/@EntrenaEII