We thus investigated the impact of one-week high-Met (2×Met–6×Met) diets on serum Met and Hcy concentrations in heterozygous Cbs+/− or Cth+/− mice (Cbs−/− mice are semi-lethal [20] and Cth−/− mice display lethal hepatitis on the 6×Met diet [18]). The gene discussed is CTH; the disease is hepatitis A virus infection.