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

Ans. is 'd' i.e., IgA+IgG2(Ref: Jawetz, 27th/e, p. 149)* IgG2 immunodeficiency 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.