Celiac Disease

Celiac disease is a chronic, immune-mediated enteropathy triggered by dietary gluten in genetically susceptible people. Ingested gluten provokes an immune response that damages the lining of the small intestine, flattening the villi and impairing absorption. It is a leading cause of malabsorption and presents with both intestinal and extra-intestinal features.

Definition

Celiac disease is an immune-mediated systemic disorder elicited by gluten and related prolamins in genetically predisposed individuals, characterised by a variable combination of gluten-dependent clinical manifestations, celiac-specific antibodies, HLA-DQ2 or HLA-DQ8 haplotypes, and enteropathy with small-intestinal villous atrophy.

Scope

The entry covers the disease's immunopathogenesis (the roles of gluten, HLA-DQ2/DQ8, and tissue transglutaminase), its clinical spectrum and associated conditions, the principles of diagnosis by serology and duodenal biopsy, and its epidemiology. It is a reference description of the disease and is not a substitute for individualised medical assessment or care.

Core questions

• How does dietary gluten trigger immune-mediated small-intestinal injury?
• What roles do HLA-DQ2/DQ8 and tissue transglutaminase play in pathogenesis?
• How is the diagnosis established with serology and duodenal histology?
• Why does the disease cause such varied intestinal and extra-intestinal manifestations?

Key concepts

• Gluten and gliadin peptides as the trigger
• HLA-DQ2/DQ8 genetic susceptibility
• Tissue transglutaminase (tTG) and deamidation
• Villous atrophy and crypt hyperplasia (Marsh grading)
• Celiac-specific serology (anti-tTG, anti-endomysial antibodies)
• Dermatitis herpetiformis and extra-intestinal disease

Mechanisms

In susceptible individuals, gluten-derived peptides resist complete digestion and reach the lamina propria, where the enzyme tissue transglutaminase deamidates them, increasing their affinity for HLA-DQ2 or HLA-DQ8 molecules on antigen-presenting cells. Presentation of these peptides activates gluten-specific CD4+ T cells, driving an inflammatory response that, together with cytotoxic effects on the epithelium, produces the characteristic crypt hyperplasia and villous atrophy (Green & Cellier, 2007; Lebwohl, Sanders, & Green, 2018). Loss of absorptive surface and brush-border enzymes leads to malabsorption, while the systemic immune activation accounts for extra-intestinal features such as dermatitis herpetiformis, anaemia, and bone disease. Antibodies against tissue transglutaminase serve as serological markers of the process.

Clinical relevance

Celiac disease is an important and treatable cause of malabsorption, iron-deficiency anaemia, and metabolic bone disease, and its recognition matters because injury is gluten-dependent. This entry summarises how the disease is characterised and diagnosed in general terms; it does not provide individualised diagnostic or dietary instructions, which require professional evaluation, and it notes only that diagnostic testing is generally performed while gluten is still being consumed.

Epidemiology

Celiac disease affects on the order of one percent of people in many Western and other populations, though a large proportion of cases remain undiagnosed because presentations are often mild or non-classical. It is more common in first-degree relatives of affected individuals and in those with certain associated autoimmune conditions, and it occurs across all ages (Lebwohl, Sanders, & Green, 2018).

Evidence & guidelines

Diagnosis and management are addressed by national and international society guidelines, including the American College of Gastroenterology update (Rubio-Tapia et al., 2023) and the British Society of Gastroenterology guidelines (Ludvigsson et al., 2014), which converge on combining celiac-specific serology with duodenal biopsy and emphasise that testing should occur on a gluten-containing diet. These documents are the authoritative reference for clinical practice.

History

A wasting childhood disorder resembling celiac disease was described in antiquity and given a modern clinical account by Samuel Gee in the late nineteenth century. The pivotal insight came from the Dutch paediatrician Willem-Karel Dicke, who during and after the Second World War linked the disease to wheat and identified gluten as the offending dietary component. Subsequent decades clarified the small-intestinal histology, the HLA association, and the central role of tissue transglutaminase, transforming celiac disease from a rare paediatric diagnosis into a recognised common immune-mediated condition.

Debates

When can the diagnosis be made without a duodenal biopsy?

Guidelines differ on whether selected patients, particularly children with very high celiac-specific antibody titres, can be diagnosed without biopsy, reflecting an ongoing balance between diagnostic certainty and procedural burden.

Key figures

• Samuel Gee
• Willem-Karel Dicke
• Peter H. R. Green

Seminal works

• green-2007
• lebwohl-2018
• rubio-tapia-2023

Frequently asked questions

What causes celiac disease?

It results from an immune reaction to gluten in people who carry susceptibility genes (HLA-DQ2 or HLA-DQ8); the reaction damages the small-intestinal lining and is the basis of the disease, though additional genetic and environmental factors influence who develops it.

Why is celiac disease diagnosed while still eating gluten?

Because the antibodies and intestinal changes used to diagnose celiac disease are driven by gluten exposure, removing gluten before testing can normalise the results and obscure the diagnosis; this is general information, not personal medical advice.