Selective serum immunoglobulin a deficiency in children with coeliac disease

Selective IgA deficiency is the most common primary immunodeficiency. The reported frequencies in coeliac disease (CD) vary widely. We studied the prevalence of isolated IgA deficiency in 176 consecutively diagnosed children with CD. Serum immunoglobulin levels (IgA, IgM, IgG), antigliadin antibodies (AGAs) of both IgA and IgG class and antiendomysial antibodies (EMAs) were determined. Sera obtained from 1386 children with abdominal colic were tested for serum immunoglobulin and used as a control. The genetic diagnostic approach includes analysis of class II HLA alleles. Four cases (2.27; 1:44) with absent or undetectably low IgA in sera were identified, significantly different from our control group (0.22%;1:462, p < 0,001). IgA deficient CD patients did not produce IgA-AGA and EMA, and had elevated levels of IgG-AGA. The observed frequency (2,27%) in these IgA deficient CD patients is about 10 times higher than in the control group, and the calculated relative risk of associated IgA deficiency is 10.72. All IgA deficient CD patients had a typical DRB1*0301-DQA1*0501-DQB1*0201 extended CD haplotype. Our study suggests that subjects with serum IgA deficiency should be screened for CD. Similarly, serum IgA should be measured to make it possible to interpret negative results for IgA-AGA and EMA.