Selective IgG Deficiency

There are five classes of immunoglobulins: IgG, IgA, IgM, IgD, and IgE. The IgG class of immunoglobulins is itself composed of four different subtypes of IgG molecules called the IgG subclasses. Patients who lack, or have very low levels of, one or two IgG subclasses, but whose other immunoglobulin levels are normal, are said to have a selective IgG subclass deficiency.