A child present with recurrent episodes of sinopulmonary infection by bacteria with polysacharide rich capsule. Deficiency of which of the following immunoglobulin subclasses should be specifically investigated -

Ans. is 'd' i.e., IgA+IgG2 Primary Immunodeficiency Diseases, Defination, Diagnosis and Management . IgG2 dificiency is the most common subclass disorder associated with recurrent infections by polysaccharide-encapsulated bacteria. Such infections are more frequent in patients with associated IgA deficiency.