Anti-Deamidated Gliadin Peptides (DGP) IgA

Key Features and Values

– Wide variety of sample types to simplify inclusion into routine serology work-up
– No observed matrix effect in paediatric samples excludes pre-treatment steps
– Ready to use reagents reduces hands-on time for assay preparation
– Long shelf life cost-effective solution by reducing wastage due to expired kits
– Suitable for inclusion on automated plate systems simplifies scale-up of test volume

Product Description

Anti Deamidated Gliadin Peptide (DPG) IgA kit is a solid phase enzyme immunometric assay (ELISA) designed for the quantitative measurement of IgA class antibodies directed against deamidated Gliadin peptides (DGP) in human serum or plasma.  Anti Deamidated Gliadin Peptide (DPG) IgA is intended for laboratory use only.

Scientific Description
Coeliac disease (CD) is defined as a chronic small-intestinal, immune-mediated enteropathy precipitated by exposure to dietary gluten (found in cereals such as wheat, barley and rye) in genetically predisposed individuals1.  It is a common autoimmune disorder, affecting ~1% of the population in many parts of the world2-3.  Genetic predisposition to CD is linked principally to several HLA system genes; in particular to genotypes DQ2 and DQ8, which are present in 95-98% of coeliac patients and occur in 20-30% of the general 4-5.  This, non IgE mediated food allergy leads to massive malabsorption disturbances and is characterised by a complete atrophy of the villi and a hyperplasia of the crypts of the upper intestine.
Serological testing for CD has evolved over time; initially these tests involved the detection of anti-Gliadin antibodies (AGA), which were subsequently found to be of low diagnostic value due to lack of sensitivity and specificity3. As a result, serological investigations have advanced to involve the detection of antibodies targeted against the auto-antigen (e.g. Tissue Transglutaminase (tTG) IgA / IgG) which remains a key assay for the determination of CD.
It has been demonstrated that coeliac subjects synthesise specific antibodies against the agent Gliadin, known as Deamidated Gliadin Peptides (DGP).  Anti-DGP antibodies are highly specific markers for identifying gluten-intolerant subjects, differently from the anti-gliadin antibodies, which are also found in healthy subjects or in subjects affected by other enteric disorders and are therefore less specific6.  The latest generation of assays therefore involve the detection of these anti- DGP antibodies.  These assays have been found to perform comparatively well against anti-TG tests7 and assays detecting anti-DGP IgG have been found to be highly accurate in patients with IgA deficiency.
In paediatric populations there is some indication that anti-DGP assays may provide further uses as these assays have a very high level of diagnostic accuracy in both high and low risk populations7-8. Several studies investigating the assessment of DGP antibody levels in paediatric populations (children under the age of 2 years) have demonstrated 100% diagnostic accuracy of this marker9-10 even in cases where normal levels of TG have been determined9.
There is an observed inverse association between anti-DGP IgA and IgG, and age at diagnosis, with children aged 7 years and under showing significantly higher values than older patients11.  Furthermore, it has been found that anti-DGP antibodies precede the appearance of TG antibodies in some children with genetic risk for CD11.  This gives rise to the possibility of using anti-DGP IgA / IgG assays as an earlier indicator for CD in certain infant populations.  A further study in infants found that levels of DGP antibodies correlated with the severity of intestinal damage12.  Use of the test for anti-DGP IgA and IgG antibodies is also recommended in all subjects, regardless of age, showing symptoms suggestive of CD and in whom the t-TG or EMA autoantibodies are absent or present only at low titres13.
Coeliac patients on gluten-free diets show a progressive reduction of anti-t-TG and anti-gliadin antibodies.  The IgG antibody titre decreases more slowly than the IgA antibody level.
Publications

1. Ludvigsson JF, Leffler DA, Bai JC, et al. The Oslo definitions for coeliac disease and related terms. Gut. 2013;62:43–52
2. Rostom A, Murray JA, Kagnoff MF. American Gastroenterological Association (AGA) Institute technical review on the diagnosis and management of celiac disease. Gastroenterology. 2006;131:1981–2002
3. Green PH, Cellier C. Celiac disease. N Engl J Med. 2007;357:1731–43
4. Sollid LM, Thorsby E. HLA susceptibility genes in celiac disease: genetic mapping and role in pathogenesis. Gastroenterology 1993; 105:910-22
5. Margaritte-Jeannin P, Babron MC, Bourgey M, Louka AS, Clot F, Percopo S, et al. HLA-DQ relative risk for celiac disease in European populations: a study of the European Genetics Cluster on Coeliac Disease. Tissue Antigens 2004; 63: 562-7
6. Berger R, Schimdt G. Evaluation of six anti-gliadin antibody assays. J Immunol Methods 1996; 191:77-86
7. Sugai E, Vazquez H, Nachman F, et al. Accuracy of testing for antibodies to synthetic gliadin-related peptides in celiac disease. Clin Gastroenterol Hepatol. 2006;4:1112–7
8. http://www.worldgastroenterology.org/UserFiles/file/guidelines/celiac-disease-english-2016.pdf
9. Barbato M, Maiella G, Di Camillo C, et al. The anti-deamidated gliadin peptide antibodies unmask celiac disease in small children with chronic diarrhoea. Dig Liver Dis. 2011;43:465–9
10. Mubarak A, Gmelig-Meyling FH, Wolters VM, Ten Kate FJ, Houwen RH. Immunoglobulin G antibodies against deamidated-gliadin-peptides outperform anti-endomysium and tissue transglutaminase antibodies in children <2 years age. APMIS. 2011;119:894–900
11. Kelly CP, Bai JC, Liu E, Leffler DA. Advances in diagnosis and management of celiac disease. Gastroenterology. 2015;148(6):1175-86
12. Amarri S, Alvisi P, De Giorgio R, Gelli MC, Cicola R, Tovoli F, Sassatelli R, Caio G, Volta U. Antibodies to Deamidated Gliadin Peptides: An Accurate Predictor of Coeliac Disease in Infancy. J Clin Immunol (2013) 33:1027–1030
13. Tonutti E, Visentini D, Picierno A, Bizzarro N, Villalta D, Bozzoli R, et al. Diagnostic efficacy of the ELISA tests for the detection of deamidated anti gliadin antibodies in the diagnosis and monitoring of celiac disease. J Clin Lab Anal. 2009; 23(3): 172-4

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Code: DKO107
Clinical Area: ,
Incubation: 30+30+15 min
Sensitivity: 100%
Specificity: 97.6%
Classification: IVD, CE
Number of Tests: 96
Sample Type: Serum/Plasma
Sample Volume: 10 µL (1:100 predilution)
Assay Range: N/A