Although it is marked by recurrent mucosal infections and the patient's presentation includes recurrent sinusitis and oral ulcers; selective IgA deficiency would only decrease IgA levels not other immunoglobulins.

Common variable immunodeficiency (CVID) is the cause of the patient's symptoms which include frequent infections, anemia, oral ulcers, and immunoglobulin findings. CVID characteristically presents in adults as recurrent bacterial infections especially of the respiratory and gastrointestinal tracts. It usually reduce levels of most or all of the immunoglobulin isotypes, causing a decreased ability to respond to infections.

This disorder presents with recurrent bacterial infections in childhood, not adulthood, and is associated with extremely low or absent B cells and all types of immunoglobulins.

Even though it is associated with normal or elevated IgM levels and recurrent infections, it reduces the levels of only IgG, IgA and IgE but does not affect cell mediated immunity and hence can not cause oral ulcers and anemia.