What is celiac disease?
Celiac disease is a chronic autoimmune disease affecting the digestive system. It is characterized by an intolerance to gluten, a protein found in wheat, barley, rye, and crossbreeds of these grains.
When a person with celiac disease consumes gluten, their immune system reacts abnormally. As a result, it attacks the lining of the small intestine, which can cause damage to the intestinal mucosa and hinder nutrient absorption (Caio et al., 2019).
Throughout this post, we will study in depth this pathology: symptoms, risk factors, and treatment, as well as the relationship between celiac disease and genetics and the possibility of DNA testing to detect genetic predisposition to celiac disease.
The symptoms of celiac disease are caused by progressive damage to the lining of the small intestine when gluten is consumed, preventing the correct absorption of certain nutrients and resulting in diarrhea, weight loss, anemia, swelling of the abdominal area, or fatigue. However, the symptoms are very nonspecific, so around 20-50% of celiac sufferers have signs compatible with irritable bowel syndrome (J. & P., Celiac disease: Review 2015). This is why it’s essential to perform genetic studies of celiac disease to facilitate its diagnosis. There is a classification of different types of celiac disease according to the other symptoms that patients with this disease may present:
- Asymptomatic celiac disease: diagnosed by serology and biopsy in patients without symptoms.
- Classical celiac disease: they present symptoms of intestinal malabsorption such as diarrhea, hypoalbuminemia, or steatorrhea.
- Non-classical celiac disease: patients presenting extraintestinal symptoms such as iron deficiency anemia, osteopenia, arthritis, or oral aphthous ulcers, among others.
- Symptomatic celiac disease: patients presenting both gastrointestinal and extraintestinal symptoms.
- Potential celiac disease: patients presenting a positive serology, but when a small intestine biopsy is performed, no histological alterations are found.
The incidence in Europe and the USA is 1%, having increased dramatically in recent years. This increase is due mainly to the increased availability of serological diagnostic screening tests with high sensitivity and specificity and the discovery of specific antibodies for this pathology. Still, even so, there are seven undiagnosed cases for every diagnosed case. In addition, several studies have warned that globalization coupled with the spread of extreme versions of the Mediterranean diet, where excessive amounts of gluten (up to 20 g/day) are included, may have triggered an increase in this disease (de Lorgeril & Salen, 2014; Volta et al., 2013).
Although serological diagnosis is nowadays performed, it should always be confirmed with a biopsy. As mentioned above, it’s a booming pathology, diagnosed in both children and adults, affecting to a greater extent people with previous diseases such as diabetes, which is a significant problem since many of the gluten-free products sold today cause a considerable increase in blood glucose. In addition, the incidence has increased to 6.5 times more since 1990 (de la Calle et al., 2020), being more prevalent in women than in men in a 2:1 ratio
(Prevalence-Celiac Disease 2019).
Fig 1. Worldwide prevalence of celiac disease (Prevalence-Celiac disease 2019).
Causes and risk factors
Celiac disease is a complex disease, which means that it’s influenced by multiple genetic variants and the environment in which the individual lives.
Regarding the celiac disease-genetic relationship, a high rate of heritability has been observed (between 10 and 15%), related in most cases to the presence of specific genes with immune functions, such as CD80, ICOSLG, and ZMIZ1, thus triggering autoimmunity reactions (Caio et al., 2019).
Regarding environmental factors, gluten stands out as the primary trigger since our diet currently has a high content of this protein, which consists of non-digestible immunogenic peptides, that is, peptides that resist the action of enzymes of the gastrointestinal tract and manage to trigger an immune response in the organism. Thus, excessive consumption of this nutrient can eventually lead to the development of celiac disease.
Other environmental factors to consider are gastrointestinal infections, prolonged use of antibiotics and proton pump inhibitors, and overpopulation of Helicobacter pylori (de la Calle et al., 2020), among others.
Prevention and treatment
There’s secondary prevention, which consists of performing diagnostic tests to detect the disease at an early stage and thus remove gluten from the diet when the damage to the organism has not been severe. (Meijer et al., 2018).
During the last few years, research has been done on the possibility of carrying out primary prevention based on an almost total reduction of gluten intake. Still, the impact of removing this nutrient from our diet has been seen, and the disadvantages outweigh the possible advantages.
Once a patient is diagnosed with celiac disease, gluten is completely removed from their diet. Typically, people notice an improvement in symptoms after one week of the diet. (Lebwohl et al., 2018).
However, it’s estimated that about 1% of celiacs don’t respond correctly to treatment, either because they don’t follow a strictly gluten-free diet or because they have some intestinal disorder that prevents them from improving despite not consuming gluten. This resistance to treatment can lead to complications such as malnutrition or even T-lymphocyte lymphoma, as it’s closely related to this digestive pathology. In this case, additional treatments are offered to alleviate the disease.
24Genetics and celiac disease
Celiac disease is a primarily genetic disease, so it’s essential to know the presence of specific genetic variants in our DNA associated with a higher risk of suffering from the disease. Patients who discover that they have a greater genetic predisposition to celiac disease can undergo diagnostic tests to confirm whether they have the disease, since as mentioned above, a large population suffering from this disease is not aware of it, so damage can occur at the intestinal level in a silent way that can be dangerous over time.
Considering that diet is directly related to this pathology, it’s crucial to know nutrigenetics, which is the science that studies how our body reacts to different nutrients according to our genotype. 24Genetics performs the nutrigenetic test, which can significantly help determine each person’s predisposition.
Prevalencia-Celiaquía (2019) Instituto Dr. Schär. Disponible en: https://www.drschaer.com/es/institute/a/prevalencia-celiaquia (fecha de consulta: 26 de abril de 2023).
J., F.E.L.I.P.E.M.O.S.C.O.S.O. y P., R.O.D.R.I.G.O.Q.U.E.R.A. (2015) Enfermedad celiaca: Revisión, Revista Médica Clínica Las Condes, 26(5), pp. 613-627. Disponible en: https://doi.org/10.1016/j.rmclc.2015.09.007.
Caio, G., Volta, U., Sapone, A., Leffler, D. A., De Giorgio, R., Catassi, C., & Fasano, A. (2019). La enfermedad celíaca: Una revisión exhaustiva actual. En BMC Medicine (vol. 17, número 1).
BioMed Central Ltd. https://doi.org/10.1186/s12916-019-1380-z de la Calle, I., Ros, G., Peñalver Miras, R., & Nieto, G. (2020). Enfermedad celíaca: causas, patología y valoración nutricional de la dieta sin gluten. Una revisión. Nutrición Hospitalaria. https://doi.org/10.20960/nh.02913
de Lorgeril, M., & Salen, P. (2014). El gluten y la intolerancia al trigo en la actualidad: ¿están implicadas las cepas modernas de trigo? International Journal of Food Sciences and Nutrition, 65(5), 577-581. https://doi.org/10.3109/09637486.2014.886185
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Lebwohl, B., Sanders, D. S., & Green, P. H. R. (2018). La enfermedad celíaca. The Lancet, 391(10115), 70-81. https://doi.org/10.1016/S0140-6736(17)31796-8
Meijer, C., Shamir, R., Szajewska, H., & Mearin, L. (2018). Prevención de la enfermedad celíaca.
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Volta, U., Caio, G., Tovoli, F., & De Giorgio, R. (2013). Non-celiac gluten sensitivity: questions still to be answered despite increasing awareness. Cellular & Molecular Immunology, 10(5), 383-392. https://doi.org/10.1038/cmi.2013.28