What is Celiac Disease
Celiac or Coeliac?
Same pronunciation and meaning but spelled differently. COELIAC is the common spelling in Europe and Australia while CELIAC is the proper spelling in North America. Both versions are pronounced like ‘silly yak’.
The word coeliac is derived from the Greek word koiliakos or koelia meaning abdomen. In America, the silent o was dropped to make the word celiac easier to spell and pronounce.
Celiac disease is not a proper name, so it is written in lower case. It is also singular and not possessive. There is no such things as Celiac’s disease nor can a person have celiacs disease.
For ease of reading and writing in Singapore, we use CELIAC as the standard spelling.
What Is Celiac Disease?
Celiac disease is an autoimmune disease that damages the small intestine interfering with absorption of nutrients and causing systemic problems.
When people with celiac disease eat foods containing gluten (a protein present in wheat, rye, and barley), an immune reaction occurs in their small intestine. The nature of this immune response is not an allergic reaction but a delayed type of immune response. The malabsorption of nutrients may affect any organ system in the body. The intestine becomes chronically inflamed which, in turn contributes to whole body symptoms.
How Does This Happen?
The small intestine is the site of digestion of the food we eat (the breaking down of food into smaller components that can be absorbed). The bits include proteins, carbohydrates, fats, minerals, and vitamins. The small intestine then absorbs these nutrients and releases them into the bloodstream, which carries them to all tissues and cells of the body.
Essential to the absorption process are tiny villi, which line the small intestine. These tiny finger-like projections greatly expand the intestine’s surface area, maximizing the effective absorption of nutrients into the bloodstream. There are also some digestive enzymes attached to the villi of the duodenum (such as lactase to digest dairy sugar, lactose) which aids in digestion.
When the immune system of an individual with celiac disease is triggered, it attacks and destroys intestinal villi (atrophy). Without the villi, nutrients cannot be fully absorbed. This is called malabsorption. Celiac disease can interfere with absorption of all nutrients.
In addition to damaging the villi, the immune response in the intestine causes marked inflammation and creates antibodies including antibodies to food components (anti-gliadin antibodies) and auto antibodies (tissue transglutiaminase and endomysial antibodies). These antibodies may attack and damage other organs. They are also used as the basis of diagnostic tests for celiac disease.
What Causes Celiac Disease?
Celiac disease occurs as a result of genetic factors, gluten exposure in the gastrointestinal tract, and other environmental factors. The genes necessary for celiac disease to occur include HLA DQ2 and HLA DQ8. However, these genes are very common, occurring in about 30% of the general population. Other genes are also necessary and so far approximately 50 have been described. The known environmental factors that may contribute to the development of celiac disease in children include birth by Caesarian Section, and gastrointestinal infections.
Celiac disease may develop at any age from infancy to old age and occurs equally in males and females.
Celiac Disease and Genetics
Currently there are two celiac disease genetic risk factors that have been identified, HLA-DQ2 and HLA-DQ8 haplotypes. Nearly 100% of patients with Celiac Disease have one or both of these genetic risk factors but having one of these genetic risk factors doesn’t automatically make one have celiac disease. Up to 30-40% of the general population with have HLA-DQ2 but only 2-3% of this group would actually develop celiac disease. Genetic testing is often used to help someone rule out the possibility of celiac disease when one is on a prolonged gluten-free period and does not wish to do a gluten challenge in order to identify positive celiac disease antibodies or endoscopic changes to the small intestines. Your “genes” are your “genes” and don’t get affected by diet or being gluten-free. If you test positive for one or both of these genetic risk haplotypes, it does not equate to having celiac disease.
How Does One Inherit Celiac Disease?
Celiac disease is a multifactorial disorder and cannot be inherited. What can be inherited are the genetic risks for celiac disease such as the HLA- DQ2 or HLA-DQ8 haplotype. A child has a 50% chance of inheriting one of these haplotypes from their parent if their parent carries one of the genetic risks. In order to then develop celiac disease, one needs to have the genetic risk as well as exposure to gluten and some other environmental factors or stressors on the body (ie: infectious agent, physical stress such as childbirth).