Celiac disease is a chronic autoimmune disorder that affects millions of people worldwide. While the exact cause is still unknown, genetics plays a crucial role in the predisposition to this condition. In this article, we will focus on HLA-DQ haplotypes as key genetic markers in the complex diagnosis of celiac disease.
What is Gluten?
Let's start from the beginning. Gluten is a protein found in various grains such as wheat, barley, and rye. It is responsible for the elasticity of dough and is widely used in the food industry to improve the texture of baked goods and as a thickening agent in many processed foods.
In celiac disease, gluten triggers an immune response that attacks the lining of the small intestine. This can cause damage to the intestinal villi responsible for nutrient absorption. Symptoms of celiac disease may include abdominal pain, diarrhea, weight loss, fatigue, and nutrient malabsorption. If left untreated, celiac disease can have serious long-term consequences.
If you have celiac disease, the lifelong treatment is a gluten-free diet. This involves avoiding foods such as bread, pasta, cereals, cookies, and other baked goods that contain wheat, barley, rye, or ingredients derived from them. Nowadays, there is a wide variety of gluten-free alternatives available in the market to help individuals with celiac disease maintain a balanced and tasty diet. However, it is important to be cautious when choosing gluten-free products as many of them are highly processed
It is crucial to remember that just because a product is labeled "gluten-free" does not guarantee its healthiness. Many gluten-free products on the market contain a large number of unhealthy ingredients associated with cardiometabolic health issues. Therefore, it is essential to read labels and prioritize naturally gluten-free food groups such as fruits, vegetables, and legumes for maintaining a healthy diet.
If you experience symptoms and suspect gluten intolerance, it is recommended to seek the assistance of a specialized nutritionist or medical professional for an accurate diagnosis. In this process, the HLA-DQ haplotype can be of great help. This genetic analysis can reveal whether you have a genetic predisposition to celiac disease, which can help confirm or rule out the possibility of gluten intolerance.
What are HLA-DQ Haplotypes and Why are They Important in Celiac Disease?
A haplotype is a set of genetic markers that tend to be inherited together. This means that when you inherit a specific genetic variant, it is likely to come along with other specific genetic variations. It also occurs in certain sets of genes such as the HLA-DQ gene region.
HLA-DQ haplotypes play a crucial role in antigen presentation and immune system activation in response to gluten. Specifically, HLA-DQ2 and HLA-DQ8 have been identified as significant genetic risk factors in the development of celiac disease. In the presence of these haplotypes, antigen-presenting cells have a higher affinity for gluten, contributing to the characteristic immune response.
These haplotypes are present in approximately 90% of individuals with celiac disease. Specifically, HLA-DQ2 is found in 90% of cases, while HLA-DQ8 is found in the majority of the remaining cases. Interestingly, the HLA-DQ2 haplotype exhibits a dose effect, meaning that individuals who have two copies of this haplotype have a five-fold higher risk of developing celiac disease.
It is important to emphasize that having the HLA-DQ2 and/or DQ8 haplotypes is a necessary but not sufficient condition for developing celiac disease. In other words, you can carry these risk haplotypes but never develop celiac disease, as other environmental and immunological factors also influence the development of this condition.
How is Celiac Disease Diagnosed?
The diagnosis of celiac disease in adults with clinical suspicion or at risk of developing it is based on a combination of clinical tests. In many cases, an intestinal biopsy is required to confirm the diagnosis. In addition to genetic testing, clinical tests such as blood detection of anti-tissue transglutaminase (tTG), anti-endomysium (EMA), and anti-deamidated gliadin peptides (anti-DGP) antibodies are used. The presence of these proteins in the blood can indicate celiac disease.
If the results of the blood tests and/or genetic evaluation are positive, an intestinal biopsy is necessary to assess the characteristic changes of celiac disease, such as damage to the intestinal villi and the presence of inflammatory cells. It is important to note that to obtain accurate results, it is recommended that the person continue to consume gluten in their regular diet before undergoing the tests, as a gluten-free diet can alter the results.
In cases where there are clinical suspicions but both the serological and genetic tests are negative, other possible causes of symptoms similar to celiac disease, such as non-celiac gluten sensitivity, should be investigated.
What is Non-Celiac Gluten Sensitivity?
Non-celiac gluten sensitivity is a term used to describe symptoms and discomfort experienced by some individuals after consuming gluten, but without showing evidence of the characteristic damage to the lining of the small intestine seen in celiac disease. Unlike celiac disease, there is no autoimmune response or production of specific antibodies.
Non-celiac gluten sensitivity is a complex phenomenon and is not as extensively studied as celiac disease. It has been observed that some individuals with this sensitivity may also have the HLA-DQ2 and HLA-DQ8 haplotypes, although their relevance is suspected to be minimal.
To date, the pathological mechanisms, environmental factors, and genetic variants that predispose individuals to this condition remain unknown. Other genes and biomarkers are being investigated in order to establish a diagnostic protocol for this gluten-related condition.
In summary, HLA-DQ haplotypes, particularly HLA-DQ2 and HLA-DQ8, have proven to be significant genetic markers in the study of celiac disease. Discover your own haplotype at ADNTRO!