Deamidated Gliadin Peptides (DGP), IgG Antibodies - Diagnostic Tests

Deamidated gliadin peptides (DGP) antibodies are autoantibodies significant in diagnosing and monitoring celiac disease (CD), an autoimmune disorder triggered by gluten ingestion in genetically predisposed individuals.

DGP antibodies are classified into two main types: IgA DGP and IgG DGP antibodies.

IgA DGP antibodies target deamidated gliadin peptides and are highly specific for celiac disease, making them commonly used in diagnostic tests.

IgG DGP antibodies also target deamidated gliadin peptides and are particularly useful in individuals with selective IgA deficiency, a condition more common in celiac disease patients.

The formation of DGP antibodies is linked to the abnormal immune response triggered by gluten ingestion in celiac disease. Gliadin, a component of gluten, undergoes deamidation catalyzed by the enzyme tissue transglutaminase (tTG). The immune system recognizes the deamidated gliadin peptides as antigens, leading to the production of DGP antibodies.

Clinically, DGP antibodies are vital for the diagnosis of celiac disease. Their presence, symptoms, and other serological markers, such as tTG antibodies, support the diagnosis. Additionally, DGP antibodies are used to monitor adherence to a gluten-free diet (GFD); a decrease or absence of these antibodies indicates good adherence and a favorable response to treatment. DGP antibodies are advantageous in detecting celiac disease in young children and individuals with IgA deficiency.

The advantages of DGP antibodies include their high specificity and sensitivity, especially for IgA DGP antibodies, which have high diagnostic accuracy for celiac disease. Due to the importance of IgG DGP antibodies, they are also crucial for diagnosing celiac disease in individuals with selective IgA deficiency. However, there are limitations, such as potential false negatives in the early stages of the disease or individuals on a low-gluten diet and occasional false positives, particularly in individuals with other autoimmune diseases.

Compared with other celiac disease markers, tTG antibodies (IgA and IgG) are the primary markers due to their high sensitivity and specificity. However, DGP antibodies often complement by tTG antibodies, especially in challenging cases. Endomysial antibodies (EMA) are highly specific for celiac disease.

DGP antibodies are crucial for diagnosing and managing celiac disease, providing valuable information alongside other serological markers. Their importance is particularly highlighted in specific populations, such as young children and individuals with IgA deficiency, making them essential in clinical practice.