Immunoglobulin A deficiency in celiac disease in the United States

Background and Aims: Multiple European studies report increased prevalence of selective immunoglobulin A deficiency (SIgAD) and partial immunoglobulin A deficiency (PIgAD) in patients with celiac disease (CD). However; prospective data representing North American adults are lacking. While SIgAD precludes the use of IgA-tissue-transglutaminase antibody (IgA-tTG), the effect of PIgAD on IgA-tTG sensitivity is not well documented. We aim to determine the prevalence and impact of IgA deficiency on CD presentation and diagnosis in North American adult patients. Methods: We reviewed 1000 consecutive patients undergoing IgA-tTG testing and 243 healthy controls. Eligible sera were tested for IgA-tTG, serum immunoglobulins, and IgA/IgG-deamidated gliadin peptide (IgA/IgG-DGP). Results: Prevalence of SIgAD was marginally higher in patients with CD (1.9%) compared with healthy controls (0.4%, P=0.24) and patients without CD (0.7%, P=0.173). Prevalence of PIGAD was similar in patients with CD (4.8%) compared with healthy controls (5.9%, P=0.57) and patients without CD (7.2%, P=0.22). One (16.7%) of 6 patients with CD with SIgAD and all 15 (100%) with PIGAD tested IgA-tTG positive prior to gluten-free diet initiation. Patients with CD with SIGAD showed lower frequency of gastrointestinal symptoms (33% vs 82%, P=0.01) and more co-morbid autoimmune disease (67% vs 23%, P=0.03) when compared with patients with CD with normal IgA. Conclusions: The prevalence of SIgAD in North American patients with CD is comparable with European data but not significantly different than control populations. Patients with CD with SIgAD exhibit decreased IgA-tTG sensitivity and lack of gastrointestinal symptoms. PIgAD is common in patients with gastrointestinal disorders but does not alter CD presentation or IgA-tTG sensitivity.