In a subject with pneumococcal polysaccharide vaccination-specific IgG2 deficiency, the balance of specific IgG subclass antibodies changed from IgG2 > IgG1 > IgG3 > IgG4 pre-vaccination to IgG1 > IgG3 > IgG2 > IgG4 post-vaccination [6]. Here, IGHG3 is linked to hyperinsulinemic hypoglycemia, familial, 4.