Immunoglobulin a Deficiency in Coeliac Disease: A Scoping Review.

Coeliac disease (CeD) and immunoglobulin A deficiency (IgAD) frequently co-occur and share a genetic background within the HLA-DQ2 region. Although this has been known for decades, the underlying mechanisms linking the two conditions remain unclear. We conducted a scoping review to evaluate the prevalence, clinical characteristics, diagnostic challenges and histopathological features of IgAD in patients with CeD. Thirty-one studies published between 1985 and 2024 were included. IgAD was more prevalent among individuals with CeD, 1.4%-4.8% than in the general population, and CeD occurred in 5.9%-14.1% of patients with IgAD. Most patients presented with gastrointestinal symptoms, although selection bias was common. IgG-based serology remains essential for diagnosis and monitoring, but its reliability during follow-up is limited by the slow decline of antibodies. Histological findings indicate compensatory IgM and IgG responses and persistent mucosal immune activation. Improved strategies for diagnosis and long-term monitoring of patients with both conditions are warranted.