Sorted By Test Name - Mayo Medical Laboratories

DGGL
89030
usefulness of deamidated gliadin antibodies in the diagnosis of celiac disease. Clin Gastroenterol Hepatol.
2008 Apr;6(4):426-32 6. 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;4:1112-1117
Gliadin (Deamidated) Antibody, IgG, Serum
Clinical Information: Celiac disease (gluten-sensitive enteropathy, celiac sprue) results from an
immune-mediated inflammatory process that occurs in genetically susceptible individuals following
ingestion of wheat, rye, or barley proteins.(1) The inflammation in celiac disease occurs primarily in the
mucosa of the small intestine, which leads to villous atrophy.(1) Common clinical manifestations related
to gastrointestinal inflammation include abdominal pain, malabsorption, diarrhea, and/or constipation.(2)
Clinical symptoms of celiac disease are not restricted to the gastrointestinal tract. Other common
manifestations of celiac disease include failure to grow (delayed puberty and short stature), iron
deficiency, recurrent fetal loss, osteoporosis, chronic fatigue, recurrent aphthous stomatitis (canker sores),
dental enamel hypoplasia, and dermatitis herpetiformis.(3) Patients with celiac disease may also present
with neuropsychiatric manifestations including ataxia and peripheral neuropathy, and are at increased risk
for development of non-Hodgkin lymphoma.(1,2) The disease is also associated with other clinical
disorders including thyroiditis, type I diabetes mellitus, Down syndrome, and IgA deficiency.(1,3) Celiac
disease tends to occur in families; individuals with family members who have celiac disease are at
increased risk of developing the disease. Genetic susceptibility is related to specific HLA markers. More
than 97% of individuals with celiac disease in the United States have DQ2 and/or DQ8 HLA markers
compared to approximately 40% of the general population.(3) A definitive diagnosis of celiac disease
requires a jejunal biopsy demonstrating villous atrophy.(1-3) Given the invasive nature and cost of the
biopsy, serologic tests may be used to identify individuals with a high probability of having celiac disease.
Because no single laboratory test can be relied upon completely to establish a diagnosis of celiac disease,
those individuals with positive laboratory results should be referred for small intestinal biopsy, thereby
decreasing the number of unnecessary invasive procedures. Celiac disease is associated with a variety of
autoantibodies, including endomysial (EMA), tissue transglutaminase (tTG), and deamidated gliadin
antibodies.(4) Although the IgA isotype of these antibodies usually predominates in celiac disease,
individuals may also produce IgG isotypes, particularly if the individual is IgA deficient.(2) The most
sensitive and specific serologic tests are tTG and deamidated gliadin antibodies. Testing for IgA and IgG
antibodies to unmodified gliadin proteins is no longer recommended because of the low sensitivity and
specificity of these tests for celiac disease; however, recent studies have identified specific B-cell epitopes
on the gliadin molecule that, when deamidated by the enzyme tissue transglutaminase, have increased
sensitivity and specificity for celiac disease.(5,6) The tests for deamidated gliadin antibodies, IgA and
IgG, replace the older gliadin antibody tests, which have been discontinued at Mayo Clinic. The
sensitivity and specificity of test DGLDN/89031 Gliadin (Deamidated) Antibodies Evaluation, IgG and
IgA, Serum for untreated, biopsy-proven celiac disease were comparable to TSTGP/83671 Tissue
Transglutaminase (tTG) Antibodies, IgA and IgG Profile, Serum in a recent study conducted at Mayo
Clinic.(5) The treatment for celiac disease is maintenance of a gluten-free diet.(1-3) In most patients who
adhere to this diet, levels of associated autoantibodies decline and villous atrophy improves. This is
typically accompanied by an improvement in clinical symptoms. For evaluation purposes, all serologic
tests ordered for the diagnosis of celiac disease should be performed while the patient is on a
gluten-containing diet. Once a patient has initiated the gluten-free diet, serologic testing may be repeated
to assess the response to treatment. In some patients, it may take up to 1 year for antibody titers to
normalize. Persistently elevated results suggest poor adherence to the gluten-free diet or the possibility of
refractory celiac disease.(1) See Celiac Disease Diagnostic Testing Algorithm in Special Instructions for
the recommended approach to a patient suspected of celiac disease. An algorithm is available for
monitoring the patient's response to treatment, see Celiac Disease Routine Treatment Monitoring
Algorithm in Special Instructions. For your convenience, we recommend utilizing cascade testing for
celiac disease. Cascade testing ensures that testing proceeds in an algorithmic fashion. The following
cascades are available; select the appropriate one for your specific patient situation. Algorithms for the
cascade tests are available in Special Instructions. -CDCOM/89201 Celiac Disease Comprehensive
Cascade: complete testing including HLA DQ -CDSP/89199 Celiac Disease Serology Cascade: complete
testing excluding HLA DQ -CDGF/89200 Celiac Disease Comprehensive Cascade for Patients on a
Gluten-Free Diet: for patients already adhering to a gluten-free diet To order individual tests, see Celiac
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