Gluten-related disorders

The following classification of gluten-related disorders was announced in 2011 by a panel of experts in London, and published in February 2012: • Autoimmune disorders: celiac disease, dermatitis herpetiformis, gluten ataxia • Non-autoimmune, non-allergic: disorder with unknown cause, likely immune-modulated: non-celiac gluten sensitivity (NCGS) • Allergic: food allergy (IgE-mediated and non-IgE-mediated), wheat dependent exercise induced anaphylaxis (WDEIA), baker's asthma, contact dermatitis. Autoimmune disorders Autoimmune conditions related to gluten include celiac disease, dermatitis herpetiformis, and gluten ataxia. There is research showing that in people with gluten ataxia early diagnosis and treatment with a gluten-free diet can improve ataxia and prevent its progression. The population of people with gluten ataxia and other neurological conditions appears to have a different HLA distribution, in particular more HLA-DQ1, compared to most persons with celiac disease, who have HLA-DQ2 and HLA-DQ8. Coeliac disease Coeliac disease (American English: celiac) (CD) is one of the most common chronic, immune-mediated disorders, triggered by the eating of gluten, a mixture of proteins found in wheat, barley, rye, and derivatives. These alleles can stimulate a T cell, mediated immune response against tissue transglutaminase (TTG), an enzyme in the extracellular matrix, leading to inflammation of the intestinal mucosa and eventually villous atrophy of the small intestine. This is where the innate and adaptive immune response systems collide. of the small intestine. CD is not only a gastrointestinal disease. It may involve several organs and cause an extensive variety of non-gastrointestinal symptoms. Most importantly, it may often be completely asymptomatic. Added difficulties for diagnosis are the fact that serological markers (anti-tissue transglutaminase [TG2]) are not always present and many people may have minor mucosal lesions, without atrophy of the intestinal villi. Diagnosis of CD should be based on a combination of person's familial history, genetics (i.e. presence of HLA DQ2/DQ8) serology and intestinal histology. but most cases remain unrecognized, undiagnosed and untreated, and exposed to the risk of long-term complications. People may experience severe disease symptoms and be subjected to extensive investigations for many years before a proper diagnosis is achieved. Untreated CD may result in the lack of absorption of nutrients, reduced quality of life, iron deficiency, osteoporosis, an increased risk of intestinal lymphomas and greater mortality. gluten ataxia, psoriasis, vitiligo, autoimmune hepatitis, dermatitis herpetiformis, primary sclerosing cholangitis, and more.) and adults. With continuous mass genetic modification of grain crops, for reasons such as resistance to drought and pests, the occurrence of diagnosed CD had increased by 400% in the past 50 years alone. Despite its name, DH is neither related to nor caused by herpes virus: the name means that it is a skin inflammation having an appearance similar to herpes. The age of onset is variable starting in children and adolescence but can also affect individuals of both sexes indistinctly at any age of their lives. DH can relatively commonly present with atypical manifestations, which makes its diagnosis more difficult. Some people may show erythema or severe pruritus alone, wheals of chronic urticaria, purpuric lesions resembling petechiae on hands and feet, palmo-plantar keratosis, leukocytoclastic vasculitis-like appearance, and/or lesions mimicking prurigo pigmentosa. DH may be confused with many different cutaneous lesions, such as atopic dermatitis, eczema, urticaria, scabies, impetigo, polymorphic erythema and other autoimmune blistering diseases. Gluten ataxia Gluten ataxia is an autoimmune disease triggered by the ingestion of gluten. Gluten ataxia accounts for 40% of ataxias of unknown origin and 15% of all ataxias. Less than 10% of people with gluten ataxia present any gastrointestinal symptom, yet about 40% have intestinal damage. after coeliac disease and wheat allergy are excluded. with a prevalence estimated to be 6–10 times higher. Gastrointestinal symptoms, which resemble those of irritable bowel syndrome (IBS), may include any of the following: abdominal pain, bloating, bowel habit abnormalities (either diarrhea or constipation), nausea, aerophagia, gastroesophageal reflux disease, and aphthous stomatitis. joint and muscle pain, principally schizophrenia, ATIs are about 2–4% of the total protein in modern wheat and 80–90% in gluten. Furthermore, associated to gluten sensitivity, NCGS people may often present IgE-mediated allergies to one or more foods Wheat allergy People can also experience adverse effects of wheat as result of a wheat allergy. The treatment of wheat allergy consists of complete withdrawal of any food containing wheat and other gluten-containing cereals. Nevertheless, some people can tolerate barley, rye or oats. Other conditions or risk factors Antibodies to α-gliadin have been significantly increased in non-celiacs individuals with oral ulceration. Anti-α-gliadin antibodies are frequently found in celiac disease (CD), to a lesser degree subclinical CD, but are also found in a subset who do not have the disease. Of people with pseudo-exfoliation syndrome, 25% showed increased levels of anti-gliadin IgA. Other people that are also at risk are those taking gluten despite having the disorder, or whose family members have CD. In addition people with autoimmune conditions are also at risk for CD. It has just been found that there is a risk of death in CD. Therefore, gluten intake should be limited before or even after the diagnosis. One-fourth of people with Sjögren's syndrome had responses to gluten; of five that had positive response to gluten, only one could be confirmed as CD and another was potentially , the remaining three appeared to be gluten-sensitive. All were HLA-DQ2 and/or DQ8-positive. == Symptoms ==

More than 250 symptoms of gluten sensitivity have been reported, including bloating, abdominal discomfort or pain, constipation and diarrhea. Sensitivity may also present with extraintestinal symptoms, including headache, "brain fog", tingling and/or numbness in hands and feet, fatigue, as well as muscular disturbances and bone or joint pain; also neuropsychiatric manifestations ("gluten-sensitive idiopathic neuropathies") have been reported on. Complications Studies using anti-gliadin antibodies (AGA) reveal that individuals with AGA have an increasing risk for lymphoid cancers and decreased risk for other conditions associated with affluence. ==Causes==

When enteropathy develops in early childhood, symptomatic disease is more rapidly evident. A survey of geriatrics with celiac disease in Finland revealed that the incidence of disease was much higher than the general population. Allergic disease may rise or fall with age; certain evidence points to the increased or daily use of non-steroidal anti-inflammatory factors (aspirin, ibuprofen) as an increased risk factor for urticaria or anaphylaxis, and the sensitizing dose may include low-dose aspirin therapy used in the treatment of heart disease. NCGS may be a late-onset condition: in a prospective study performed among adults of 18 to 80 years, the median age of disease onset was found to be 55 years, with a six times higher prevalence in females than in males. The pathogenesis of NCGS is not yet well understood. There is evidence that not only gliadin (the main cytotoxic antigen of gluten), but also other proteins named ATIs which are present in gluten-containing cereals (wheat, rye, barley, and their derivatives) may have a role in the development of symptoms. ATIs are potent activators of the innate immune system. As of 2019, reviews have concluded that although FODMAPs may play a role in NCGS, they only explain certain gastrointestinal symptoms, such as bloating, but not the extra-digestive symptoms that people with NCGS may develop, such as neurological disorders, fibromyalgia, psychological disturbances, and dermatitis. In NCGS, there is high AGA IgG in more than half of the cases. In wheat allergy, there appears to be an innate component and the response pathways are mediated through IgE against gliadin and other wheat proteins. == Pathophysiology ==

Compared to the pathophysiology of celiac disease, the pathophysiology of NCGS is far less understood. A literature review of 2014 found that people with NCGS "are a heterogeneous group, composed of several subgroups, each characterized by different pathogenesis and clinical history, and, probably, clinical course". Genetics Celiac disease (CD) and NCGS are closely linked with human leukocyte antigen (HLA) class II genes, HLA-DQ2 and HLA-DQ8, located on chromosome 6p21. Nearly all CD people are HLA-DQ2/HLA-DQ8 positive, with 95% HLA-DQ2 and the rest usually HLA-DQ8 (which is carried by 30% of Caucasians). However, the specificity of HLA-DQ2 and/or HLA-DQ8 for CD is low, with estimates ranging from 36% to 53%. In persons with NCGS, the HLA-DQ2 and/or HLA-DQ8 alleles are present in only about 50%, which is still a greater proportion than in the general population. == Diagnosis ==

A literature review of 2014 found that non-coeliac gluten sensitivity diagnosis can be reached only by excluding celiac disease (CD) and wheat allergy. Eliminating the possibility of CD can generally also be done by adding HLA-DQ typing. The absence of HLA-DQ2 and HLA-DQ8 has a very high negative predictive value for CD, and the predictive value can be further enhanced by including HLA-DQ7.5 (HLA-DQ2 and HLA-DQ8 are found in coeliac disease 98% of the time in Caucasians, HLA-DQ7.5 present in the remaining 1.6% and only 0.4% of Caucasians are missed with the combination of these three). Without serological or HLA-DQ2/8 positivity, celiac disease is likely not present. HLA-DQ typing has a practical advantage in that it is the only diagnostic test that allows to exclude CD when a person is already on a gluten-free diet; however, as not only celiacs are HLA-DQ2/HLA-DQ8 positive, this method has a higher false positive rate than anti-TG2 and EMA antibody testing. A four-of-five rule was proposed 2010 for confirming celiac disease, with the disease confirmed if at least four of the following five criteria are satisfied: • typical symptoms of celiac disease; • positivity of serum celiac disease immunoglobulin, A class autoantibodies at high titer; • human leukocyte antigen (HLA)-DQ2 or DQ8 genotypes; • celiac enteropathy at the small bowel biopsy; and • response to the gluten-free diet. For diagnosis of wheat allergy, allergy tests are available. == Treatment ==

For people with celiac disease, a lifelong strict gluten-free diet is the only effective treatment to date; For people diagnosed with non-celiac gluten sensitivity, there are still open questions concerning for example the duration of such a diet. The results of a 2017 study suggest that non-celiac gluten sensitivity may be a chronic disorder, as is the case with celiac disease. Knowledge of hidden sources of gluten is important for people with celiac disease as they need to be very strict regarding eating only gluten-free food. The degree of gluten cross contamination tolerated by people with non-celiac gluten sensitivity is not clear but there is some evidence that they can present with symptoms even after consumption of small amounts. A part of people with gluten-related neuropathy or gluten ataxia appears not to be able to tolerate even the traces of gluten allowed in most foods labeled as "gluten-free". The inclusion of oats in gluten-free diets remains controversial. Avenin present in oats may also be toxic for individuals with celiacs. Its toxicity depends on the cultivar consumed. Furthermore, oats are frequently cross-contaminated with gluten-containing cereals. Potential nutritional deficiencies Gluten proteins have low nutritional value and replacing grains that contain gluten is easy from the nutritional point of view. However, an unbalanced selection of food and an incorrect choice of gluten-free replacement products may lead to nutritional deficiencies. Replacing flour from wheat or other gluten-containing cereals with gluten-free flours in commercial products may lead to a lower intake of important nutrients, such as iron and B vitamins. Some gluten-free commercial replacement products are not enriched or fortified as their gluten-containing counterparts, and often have greater lipid/carbohydrate content. Children especially often over-consume these products, such as snacks and biscuits. Pseudocereals (quinoa, amaranth, and buckwheat) and some minor cereals are healthier alternatives to these prepared products and have higher nutritional value. Furthermore, they contain protein of higher nutritional quality than those of wheat, and in greater quantities. Nutritional complications can be prevented by a correct dietary education. == Epidemiology ==

In the United States, fewer cases of CD have been found compared to other countries. The incidence of celiac disease and of wheat allergy is estimated each to lie at around 1% of the population. There has been a 6.4 increase in the case reports of celiac disease between 1990 and 2009. In Europe, the average consumption of gluten is 10g to 20g per day, with parts of the population reaching 50g or more per day. == Histology ==

Changes in inflammatory cells affect the body, which reduces the intake of "nutrients, fat-soluble vitamins and minerals" in the body. == Regulations ==

In various countries, regulations and labelling requirements for gluten-free food products have been implemented. For Europe, the Commission Regulation (EC) No. 41/2009 of 20 January 2009 concerning the composition and labelling of foodstuffs suitable for people intolerant to gluten has laid down harmonised rules on the content and labelling of these foodstuffs, setting out the conditions under which foods may be labelled as "gluten-free" or "very low gluten". Having entered into force on 10 February 2009 and taken effect on 1 January 2012, these rules have been repealed with effect as of 20 July 2016. The background is that, in line with the Regulation (EU) No 609/2013 on food for specific groups, gluten-free foods shall, in future, be legislated for under the EU Food Information for Consumers Regulation (Regulation (EU) No. 1169/2011). Furthermore, the Commission Implementing Regulation (EU) No 828/2014 of 30 July 2014 on the requirements for the provision of information to consumers on the absence or reduced presence of gluten in food extends the rules of Regulation (EC) 41/2009 on "gluten-free" and "very low gluten" statements also to non pre-packed foods such as those served in restaurants. The implementing regulation also clarifies how consumers are to be informed of the difference between foods that are naturally free of gluten and products that are specially formulated for gluten-intolerant persons. Recognition of gluten-free packaged foods is facilitated by the crossed-grain symbol, representing a crossed ear of wheat. The symbol is used as a logo that facilitates food shopping for people with CD and other gluten-related disorders. The symbol, which is protected as a trademark in Europe and the United States and is covered by worldwide copyright, can be represented in any colour. == Research ==

Research has attempted to discern, by double-blind placebo-controlled trials, between a "fad component" to the recent popularity of the gluten-free diet and an actual sensitivity to gluten or other components of wheat. In a 2013 double-blind, placebo-controlled challenge (DBPC) by Biesiekierski et al. in a few people with irritable bowel syndrome, the authors found no difference between gluten or placebo groups and the concept of NCGS as a syndrome was questioned. Nevertheless, this study had design errors and an incorrect selection of participants, and probably the reintroduction of both gluten and whey protein had a nocebo effect similar in all people, and this could have masked the true effect of gluten/wheat reintroduction. In a 2018 double-blind, crossover research study on 59 persons on a gluten-free diet with challenges of gluten, fructans or placebo, intestinal symptoms (specifically bloating) were borderline significantly higher after challenge with fructans, in comparison with gluten proteins (P=0.049). Although the differences between the three interventions was very small, the authors concluded that fructans (the specific type of FODMAP found in wheat) are more likely to be the cause of NCGS gastrointestinal symptoms, rather than gluten. In addition, fructans used in the study were extracted from chicory root, so it remains to be seen whether the wheat fructans produce the same effect. == See also ==