IGHG3 and common variable immunodeficiency: In a detailed study of two mothers with IVIg treated CVID and their newborns, it was demonstrated that cord blood IgG levels were greater than maternal IgG; subclasses IgG1, IgG3, and IgG4 were preferentially transferred compared with IgG2; anti-protein (tetanus) IgG antibodies were equivalent to or higher than maternal levels with good transfer of polysaccharide (Hib) IgG antibodies; and anti-Streptococcus pneumoniae avidity indices were similar between mothers and their neonates [6].