Progression of selective IgA deficiency to common variable immunodeficiency.

Selective IgA deficiency (IgAD) is the most common primary immunodeficiency in Caucasians. Although it is often asymptomatic, selected patients show an increased frequency of infections, allergies and autoimmune manifestations. Common variable immunodeficiency (CVID) is a primary antibody deficiency disease that shares many clinical features with IgAD. A common genetic basis for IgAD and CVID has been suggested based on their occurrence in members of the same family and the similarity of the underlying B cell defects. Progression from IgAD to CVID has also been reported in several cases. Here we present 4 patients with IgAD and autoimmune features who subsequently developed CVID. All symptomatic IgAD patients, especially those with associated IgG subclass deficiency or autoimmune features, should be monitored for evolution to CVID. Early diagnosis of this conversion and institution of immunoglobulin therapy is effective in preventing severe bacterial infections and pulmonary insufficiency.