IgG subclass deficiencies

Although the publications of the past year have added to our knowledge about IgG subclass deficiency, they have hardly added to our understanding of what constitutes IgG subclass deficiency. No definition exists today for subclass deficiency, and its relation to different diseases is unclear. In children and adults, low IgG subclasses in themselves are not an indication for immunoglobulin substitution and general recommendations cannot be given.