Coeliac disease in infants: antibodies to deamidated gliadin peptide come first!

Background

The onset of coeliac disease (CD) in the first year of life is uncommon and the diagnosis can be challenging due to the suboptimal sensitivity of tissue transglutaminase antibodies (tTG) at this age and the many other possible causes of malabsorption in infants. Antibodies to deamidated gliadin peptides (anti-DGPs), especially IgG, may appear earlier than IgA anti-tTG in very young children with CD.

Case presentation

We report here on an 8-month-old child who was evaluated for failure to thrive, constipation and developmental delay. The symptoms started following gluten introduction in the diet. Laboratory tests showed high fecal elastase concentration, normal serum IgA levels with positive IgG and IgA anti-DGPs, whereas anti-tTG were not detected. The duodenal biopsy revealed a complete villous atrophy (Marsh-Oberhuber 3C). The culture of biopsy fragments in the presence of gliadin peptides did not stimulate the production of IgA anti-endomysial antibodies. Genetic testing proved the child was positive for HLA-DQ2 (DQA1*05; DQB1*02) and HLA-DQ8 (DQA1*03, DQB1*0302). Having initiated the gluten-free diet, the symptoms disappeared and the infant experienced rapid catch-up growth with normalization of psychomotor development.

Conclusions

This case report highlights the utility of anti-DGPs for screening infants with suspected CD. The pattern with positivity for IgG and IgA anti-DGPs only is rare in IgA-competent children with biopsy-proven CD. It could be explained in infancy as immaturity of the adaptive immune system.

Anti-DFS70 antibodies: a useful biomarker in a pediatric case with suspected autoimmune disease

Antidense fine speckles 70 (anti-DFS70) antibodies, a peculiar antinuclear antibody (ANA) pattern by indirect immunofluorescence, is frequently observed in ANA-positive individuals with no evidence of systemic autoimmune rheumatic disease. They may be found in many different inflammatory conditions and in healthy individuals. We herein report a case of an 8-year-old girl presenting with generalized edema, hypertension, hepatomegaly, and a history of pharyngitis, which occurred 3 weeks earlier. Laboratory analysis revealed low complement C3 (6 mg/dL), microhematuria, and proteinuria. A diagnosis of acute glomerulonephritis was made. Anti-dsDNA, antiextractable nuclear antigens, and antineutrophil cytoplasmic antibodies were negative. However, a highly positive (1:640) ANA immunofluorescence test with dense fine speckles pattern was found. The presence of anti-DFS70 immunoglobulin G antibodies was confirmed by a specific immunoassay. In conclusion, the presence of isolated anti-DFS70 antibodies may be useful to exclude an autoimmune pathogenesis in those children with a positive ANA test and a clinical picture possibly attributable to systemic autoimmune rheumatic disease. This will avoid further unnecessary investigation with the potential for incorrect diagnosis and possibly harmful treatment.