The importance of AID to polyfunctional antibody responses is demonstrated by the positive association of AID expression with increased neutralisation breadth, IgG subclass diversity, and Fc responses following HIV-1 infection (236), as well as the diminished production of mature isotypes and reduced affinity maturation in individuals with impaired AID expression, such as the elderly or those with chronic inflammatory conditions (237–239). The gene discussed is AICDA; the disease is HIV-1 infection.