The patients with IgA deficiency have a tendency to develop recurrent sinopulmonary infections, gastrointestinal infections and disorders, allergies, autoimmune conditions, and malignancies. The IgG2 subclass contains antibodies against the polysaccharide coating of ceain disease-producing bacteria that can cause ear and sinus infections, pneumonia, blood infections and meningitis. Ref: Ananthanarayan & Panikers textbook of microbiology 9th edition pg.no. : 172,173