Gliadin (Deamidated) Antibody, IgG
(DGGL)

Sample type:

Serum Preferred Serum gel (yellow tube) acceptable red tube.

Uses:

Detection of antibodies to gliadin, one of the major protein components of gluten, is a sensitive assay useful in diagnosing celiac disease. However, gliadin antibodies may be found in individuals without celiac disease; thus, gliadin antibody assays are less specific than assays measuring antibodies to endomysium and transglutaminase.

Recent work has revealed that gliadin-reactive antibodies from celiac patients bind to a very limited number of specific epitopes on the gliadin molecule. Further, deamidation of gliadin results in enhanced binding of gliadin antibodies.

Based on this information, assays using deamidated gliadin peptides bearing the celiac-specific epitopes have much higher diagnostic accuracy for celiac disease when compared to standard gliadin antibody assays.

Nots:

1) IgA is more useful in detecting celiac disease because it’s made in the small intestine, where gluten causes inflammation and irritation in sensitive people.

2) IgG levels are less specific to celiac disease, but may still be used in diagnosing autoimmune problems, especially in people who are deficient in IgA.

Precaution:

Collection:

1. Collect and label sample according to standard protocols.

2. Gently invert tube 5 times immediately after draw. Do not shake.

3. Let tube stand in a vertical position to allow blood to clot 30 minutes.

4. Centrifuge for 10 minutes.

Transport:

Store serum at 2°C to 8°C after collection and ship the same day per

packaging instructions included with the provided shipping box.

Stability of sample :

Ambient (15-25°C): 7 days

Refrigerated (2-8°C): 14 days

Frozen (-20°C): 30 days

Interfering factors:

Some factors in technique Fluor enzyme immunoassay:

1) The availability of a specific antibody is critical, in some cases an antibody or antibody pair may not exist or their specificity may be inadequate. Poor specificity can lead to low sensitivity and false results.

2) Coupled to the above, the range of analytes and antigens that can be detected with immunoassay is somewhat limited. Also it is very difficult to identify any post-translational modifications with immunoassay.

3) Immunoassays are a multi-step process, using a complex biological molecule (antibody), in a biological reaction and as such reproducibility of the process intra- and inter-lab can be an issue. Lot-to-lot variation in the antibody product itself also has to be carefully controlled.

Pre analytical error:

Specimens other than serum; improper labeling; samples not stored properly; samples older than stability limits; gross hemolysis; gross lipemia

Corrective action:

refused the sample and ordered another sample

Post analytical error:

Writing the test result incorrectly in the patient’s report.

Corrective action:

Quickly inform the patient that the result in the report is wrong, apologize to the patient for this behavior and should receive the correct result.

Reference range:

Gliadin Antibody (IgG)

<15.0 U/mL Antibody not detected

≥15.0 U/mL Antibody detected

Gliadin Antibody (IgA)

<15.0 U/mL Antibody not detected

≥15.0 U/mL Antibody detected