This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immunology, Subject name: Microbiology
[{'content': 'A child present with recurrent episodes of sinopulmonary infection by bacteria with polysachride rich capsule. Deficiency of which of the following immunoglobulin subclasses should be specifically investigated - \nSelect and explain. \nA. IgA, B. IgG1, C. IgG2, D. IgA + IgG2', 'role': 'user'}, {'content': 'Answer: D \nExplanation: 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', 'role': 'assistant'}]