In order to investigate the influence of the modification of Tg by AGE formation on its antigenicity and immunogenicity we tested the antibody reactivity of sera from women with HT and GDM, as well as from age-matched healthy controls, against high AGE-Tg (49 AGE units/mg Tg), low AGE-Tg (13 AGE units/mg Tg), and native Tg (0.78 AGE units/mg Tg). The gene discussed is TG; the disease is hematocrit.