Genetic mutations and other causes of Crohn's
Though the researchers from UT Southwestern focused on generic mutations to mirror the symptoms of Crohn’s Disease in the mice for their study, the exact causes of Crohn’s are unknown. Current general consensus is the disease is caused by the interplay of genetic, environmental, and immune system factors.
Genetics: Family members of a Crohn’s disease sufferer are slightly more likely—10 to 20 percent—to develop the disease themselves. According to the National Health Services in the United Kingdom, if you have an identical twin with Crohn’s, you have a 70 percent chance of developing it yourself. It’s also more common among Caucasians and people from certain ethnic groups, such as Jews. A mutation of the NOD2 and ATG16L1 may cause Crohn’s disease; people with Crohn’s are twice as likely to have the gene mutation as people without. However, not all people with the mutation develop an inflamed bowel disease, like Crohn’s.
Environment: It’s unclear if environmental factors cause Crohn’s, although there is strong evidence they can irritate the disease if already present. Identified environmental factors include cigarette smoke, bacteria or viruses, and food. The disease is also heavily concentrated in developed countries, like the United States and United Kingdom, and much less prevalent in Asia and Africa. Diagnoses have also sharply risen since the 1950s. This trend implicates environmental factors, such as diet or toxins, could be a large influencer in development of the disease.
Environmental elements might trigger the perpetual inflammation response that causes painful Crohn’s symptoms or may damage the lining of the intestines permanently. As discovered in the UT Southwestern study, this intestinal lining contains a secondary immune response system critical in fighting pathogens.
Immune system damage or underdevelopment: A childhood illness that impacted the immune system could cause Crohn’s in later life. Research from University College London in the United Kingdom suggested a weakened immune system delays an immediate response to pathogens or incomplete process in removing pathogens, leading to a breach of the mucosal barrier in the intestines. This in turn may trigger a larger infection and inflated immune reaction.
Another theory links environmental factors such as hygiene and eradication of childhood diseases with causing an underdeveloped immune system; as children as increasingly exposed to fewer germs, their immune system is less able to effectively flush out pathogens.
Other theories link an increased use of broad-spectrum antibiotics to treat illness. These flush out the immune system of all bacteria, including healthy bacteria, making the immune system weaker.