Anti- deamidated gliadin peptides IgG

Anti-Deamidated Gliadin Peptide Antibodies, IgG (Anti-DGP IgG) – a key serological test for diagnosing celiac disease. These antibodies are produced in response to gluten exposure and help detect celiac disease—also known as gluten-sensitive enteropathy—particularly in genetically predisposed individuals.

Role of Gliadin and Anti-DGP Antibodies

Gliadin is a protein component of gluten, found in cereals such as wheat, rye, and barley. In celiac patients, gliadin peptides cross the intestinal epithelial barrier, triggering an immune response. A key role in this reaction is played by the enzyme tissue transglutaminase (tTG), which catalyzes the deamidation of gliadin peptides. This process converts the neutral glutamine into negatively charged glutamate, significantly increasing gliadin’s immunogenicity. The modified peptides bind more easily to antigen-presenting cells (APCs), activating both cellular (T-lymphocytes) and humoral (B-lymphocytes) immune responses.
As a result, B cells produce antibodies not only against deamidated gliadin peptides (DGP), but also against tissue transglutaminase—both being specific markers of celiac disease.
DGP antibodies are important serological markers, especially in cases where classical anti-tTG antibodies may be absent, such as in individuals with IgA deficiency.
Anti-DGP IgG is particularly useful in patients with IgA deficiency, where the standard anti-tTG IgA test may yield false negatives.

Consequences of DGP and tTG Antibody Production the immune response leads to chronic inflammation in the small intestinal mucosa, potentially causing:

• Villous atrophy
• Impaired nutrient absorption
• Malabsorption syndrome characterized by iron, B-complex vitamins, calcium, and other deficiencies
• Clinical signs of celiac disease: chronic diarrhea, weight loss, osteoporosis, anemia

Determining DGP-IgA and DGP-IgG antibody levels is a sensitive and specific laboratory test for diagnosing celiac disease. However, a definitive diagnosis requires a comprehensive approach, including clinical evaluation, laboratory markers, and histological examination of intestinal tissue.

Diagnostic Role

Anti-DGP IgG testing is recommended in the following situations:

• Diagnosing celiac disease, especially in patients with selective IgA deficiency where standard anti-tTG IgA tests may be falsely negative
• Monitoring adherence to a gluten-free diet: a decrease in antibody titers after gluten withdrawal indicates treatment efficacy

Indications for Testing

• Suspected celiac disease in patients with malabsorption symptoms: chronic diarrhea, bloating, weight loss, anemia, osteoporosis—especially in those with selective IgA deficiency
• Screening first-degree relatives of individuals with celiac disease, particularly when gastrointestinal or extraintestinal symptoms are present
• Monitoring dietary compliance and worsening of your condition in diagnosed celiac patients
• Suspected seronegative celiac disease, where other serological markers may be negative

Test Preparation

No special preparation is required, but gluten should not be excluded from the diet before testing, as this may result in false negatives.

• The test can be performed at any time of day, on an fasting or after a meal
• Avoid intense physical activity the day before testing, as it may affect results
• Do not consume alcohol or smoke within 24 hours before testing
• Ensure proper hydration to facilitate blood sample collection
• Inform your doctor about any medications or supplements, as some may influence the results

Test Procedure

The test requires a venous blood sample sample, which takes only a few minutes and is performed by trained medical personnel. After the blood draw, minor bleeding or a small bruise may appear, resolving naturally within a few days.

Sources:

https://pubmed.ncbi.nlm.nih.gov/36602836/

https://www.worldgastroenterology.org

https://gi.org/page/4/?s=celiac

https://www.nice.org.uk/guidance/ng20

https://onlinelibrary.wiley.com/doi/10.1097