Change in Gliadin Antibody Testing


Effective May 12, 2008 the Immunopathology Laboratory will no longer perform/offer IgA and IgG anti-gliadin antibody (AGA) assays. After this date, orders for the anti-gliadin antibody tests will be replaced with the corresponding IgA or IgG anti-Deamidated Gliadin Peptides (anti-DGP) assays.

Rationale: According to NIH Consensus Conference on Celiac disease (2004)1 and many published research articles2-4, the AGA tests are no longer recommended for patient screening because of their lower sensitivity and specificity. In contrast to AGA, IgA and IgG antibodies to DGP have a higher sensitivity and specificity. Several studies have now shown anti-DGP to be of similar sensitivity and specificity as anti-tTG. IgA anti-DGP is reported to have a sensitivity of 98.9% and a specificity of 98.3 while IgG anti-DGP has a sensitivity of 100% and a specificity of 96% for patients with celiac disease2. Our own laboratory’s evaluation of the anti-DGP tests on over 200 patients with celiac disease and similar number of GI disease controls confirms the high sensitivity and specificity of these tests.

Questions or comments should be directed to Dr. Sergei Syrbu (6-7372), Dr. Michael Icardi (4-8632), Dr. John Kemp (4-9611), or Lisa Horning, MT (ASCP) 356-2688.

References:
1) NIH Consensus Development Conference Statement on Celiac Disease. June, 2004 Gastroenterology 128:51-59 (2005).

2) Niveloni S, Sugai E, Cabanne A, et al. Antibodies against Synthetic Deamidated Gliadin Peptides as predictors of celiac disease: Prospective assessment in an Adult Population with a High Pretest Probability of Disease. Clin Chem 53:12, 2186-2192 (2007).

3) Alenzi M, Demonte AM, Esper C, et al. Celiac disease: antibody recognition against native and selectively deamidated gliadin peptides. Clin Chem 47: 2023-2028 (2001).

4) Schwertz E, Kahlenberg F, Sack U, et al. Serologic assay based on gliadin nonapeptides as a highly sensitive and specific diagnostic aid in celiac disease. Clin Chem 50: 2370-2375 (2004).