Gluten is a family of storage proteins found in wheat, rye, triticale, and barley. In predisposed individuals, ingestion of gluten causes disease reactions that are grouped under the term gluten-related disorders (GRD). Only a decade ago, GRD were rare in the United States, but the rate of gluten-related disorders has greatly increased since then. It is now estimated that GRD affect close to 10% of the population (Sapone et al., 2012).
There are five kinds of gluten-related disorders recognized by the medical community. Each disorder presents with unique pathophysiology and etiology. Celiac disease, dermatitis herpetiformis, and gluten ataxia are autoimmune conditions; wheat allergy is an allergic disease (Taraghikhah et al., 2020), and non-celiac gluten sensitivity is a non-autoimmune-allergic disease (Sharma et al, 2020).
Celiac Disease and Gluten
Celiac disease (CD) is a chronic, auto-immune condition that affects genetically predisposed individuals. It is thought that genetically predisposed individuals develop an immune response to unknown environmental factors which is then triggered by the ingestion of gluten (Lebwohl et al., 2018). CD can cause atrophy of the small intestinal villi, which leads to malabsorption, diarrhea, and failure to thrive. But manifestations of CD can also be minimal, like negligible mucosal lesions, or it can have an asymptomatic presentation, which often causes delayed diagnosis. Celiac disease can also present with extraintestinal manifestations ranging from neurologic disorders, psychiatric disorders, infertility, recurrent miscarriages, osteoporosis and osteopenia, arthritis, aphthous stomatitis (a disease my mother suffers from), dental enamel hypoplasia, and elevations in transaminases (Barker & Liu, 2008).
Dermatitis Herpetiformis and Gluten
Dermatitis Herpetiformis (DH), also known as Duhring-Brocq disease, is an auto-immune condition that affects the skin and causes chronic blistering and lesions. The lesions and blisters generally cover the areas of the scalp, knees, elbows, ankles, and buttocks, producing intense burning and itching. The skin of people affected by DH presents with the same protein IgA1 with J chain and secretory component found in the small intestinal mucosa in adult celiac disease, suggesting a strong correlation between the two conditions (Cohen et al., 1997). For this reason, DH is also called the “celiac disease of the skin”, and the European Society for Pediatric Gastroenterology, Hepatology and Nutrition now states that a dermatitis herpetiformis diagnosis confirms the celiac disease diagnosis without the need for intestinal biopsy. People affected by DH can suffer from various degrees of gastrointestinal issues that vary from milk lesions of the mucosal lining of the small intestine to villous atrophy (Mendez et al., 2013).
Gluten Ataxia as an Autoimmune
Gluten ataxia (GA) is an autoimmune disease triggered by the ingestion of gluten that affects primarily the cerebellum, the part of the brain responsible for coordination and movement. The cerebellum is also responsible for balance, eye movement, and the kind of motor learning abilities involved in learning movements that require practice and fine-tuning, for example, riding a bike or playing an instrument (Leopold, 2018). In GA, the immune system creates antibodies that attack and destroy the Purkinje cells, causing problems with vision and fine motor skills, gait abnormalities, and balance issues. It can also cause peripheral neuropathy, also known as gluten neuropathy (Hadjivassiliou et al., 2004). The damage to the Purkinje cells is irreversible, and studies involving brain MRIs show that up to 60% of subjects affected by GA suffer from permanent shrinkage of the cerebellum (Sapone et al., 2012).
Wheat Allergies and Gluten
Wheat allergy (WA) is an allergic reaction to gluten in which the immune system produces immunoglobulin E antibodies in response to wheat proteins. It can present with gastrointestinal symptoms similar to celiac disease, but unlike CD, WA has a fast onset. When inhaled (baker’s asthma), WA can cause asthma and rhinitis. When someone affected by WA touches wheat, skin reactions occur. When ingested, wheat causes gastrointestinal pain, diarrhea, malabsorption, and, if untreated, it can lead to failure to thrive. WA can also cause anaphylactic shock, but it does not cause villi atrophy (Elli et al., 2015).
Gluten Sensitivity
Non-celiac gluten sensitivity (NCGS) is a non-autoimmune-allergic disease that presents with gastrointestinal and/or extraintestinal symptoms similar to the ones seen in CD (altered bowel habits, skin rashes, bone pain, headaches, fatigue, and depression). Laboratory testing shows no serum antibodies, and intestinal biopsies do not show villous atrophy. This lack of biomarkers makes NCGS difficult to diagnose, and it also can lead to misdiagnosis. NCGS can be misdiagnosed as IBS, and oftentimes only a strict elimination diet allows for a conclusive diagnosis (Biesiekierski et al., 2011). Molina-Infante et al. (2014) estimate that the prevalence of NCGS is 6 to 10 times higher than CD and WA and that it is more prevalent in family members of CD sufferers.
References
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