381 Conventional AGA Positivity in Children Under Two Years of Age: Celiac Disease or Food Allergy? the Role of Anti-Deamidated Gliadin Peptide Antibodies

Abstract

Background: Chronic gastrointestinal symptoms in children aged less than two years often represent a clinical challenge for paediatricians, since discriminating between coeliac disease (CD) and food allergy (FA) in this age group might be quite tricky, as classical serum markers for CD, except anti-gliadin antibodies (AGA), are not uncommonly negative. Objective: The aim of our study was to assess the role of aDGP as diagnostic tool differentiating between CD and FA in children aging less than 24 months with high levels of serum AGA, when EmA and anti-tTG are negative. Methods: We investigated 40 children (median age: 16,8 months; age range: 4-24 months), with chronic gastrointestinal symptoms suggesting either CD or FA and with high serum levels of conventional AGA, with normal values of serum IgA, anti-transglutaminase (anti-tTG) and anti-endomysial (EmA) antibodies and without sensitization to the most common food antigens. All of them underwent measurement of serum levels of aDGP (IgA and IgG) and upper gastrointestinal endoscopy with duodenal biopsies; 40 controls were ageand sex-matched to these patients in order to clarify the aDGP specificity. Results: 29 patients (group A) had normal levels of aDGP; their histological features were compatible with Marsh I to III lesions and mimicked CD. However, all of them markedly improved on a cow's milk, soy and egg free diet containing gluten. After three months, these food antigens were reintroduced; subsequently, the vast majority of children (93,1%) belonging to group A experienced a clinical relapse and the return to the previous oligoantigenic diet was once more beneficial. On the other hand, 11 patients (group B) had high serum levels of aDGP (IgG positivity in all of them; IgA positivity in 9), whereas histology showed the same lesions of group A. HLA typing was obtained; haplotypes carried by children of group B were consistent with CD genetic pattern. Moreover, they significantly improved on a gluten free diet containing cow's milk, soy and egg. None of the control group (group C) was aDGP positive. Conclusions: Our data indicate that serum IgG aDGP may be of pivotal usefulness in identifying celiac patients under two years of age with chronic gastrointestinal symptoms and only conventional AGA positivity, distinguishing them from FA. Although the great clinical improvement with GFD in group B, gluten challenge will be permorfed to confirm CD diagnosis.