Immunoglobulin A deficiency on serological coeliac screening: an opportunity for early diagnosis of hypogammaglobulinaemia.

We present a serendipitous case of clinically significant pan-hypogammaglobulinaemia, diagnosed after routine serological testing for possible coeliac disease led first to identification of IgA deficiency (discovered as a low background in IgA-based routine serological screening), and subsequently to confirmed pan-hypogammaglobulinaemia (antibody immunodeficiency). Hypogammaglobulinaemia is a relatively rare diagnosis (estimated at 1 in 36,000), in which delayed diagnosis and treatment are associated with chronic organ damage including bronchiectasis. Routine serological testing for coeliac disease using the IgA anti-tissue transglutaminase (IgA TTG) test is in widespread use and provides an opportunity for early diagnosis of hypogammaglobulinaemia. Routine serological screening for coeliac disease may uncover IgA deficiency, and we suggest that all IgA-deficient cases identified should also be checked for antibody deficiency by quantifying the other immunoglobulins (IgG, IgM).