Dermatitis herpetiformis and partial IgA deficiency.

Although the specific IgA autoantibody responsible for the pathogenesis of dermatitis herpetiformis (DH) is unknown, the presence of IgA is considered essential in the pathogenesis of DH. To date, no cases of IgA deficiency have been reported in DH. In contrast, IgA deficiency is found in 2% to 3% of patients with celiac disease, a rate 10 to 15 times higher than the normal population. We report 2 patients with DH who also have partial IgA deficiency. We evaluated the sera of these patients for the presence of IgA autoantibodies to endomysium, tissue transglutaminase, epidermal transglutaminase, and gliadin. Both patients were found to have IgA endomysial and tissue transglutaminase antibodies, and serologic markers for DH. Corresponding IgG autoantibodies were not useful serologic markers of DH in the setting of IgA deficiency, as they often are in celiac disease. We then screened 98 DH sera for total IgA levels and identified 1 additional case with IgA deficiency. In conclusion, DH may develop in patients with partial IgA deficiency, indicating that pathogenically directed IgA antibodies are likely sufficient for cutaneous IgA deposition in this disease.