The mice are hemizygous for the human apolipoprotein A2 (ApoA2) gene expressed under the control of the homologous promoter (-911/+2045). They are humanized because they are deficient in mouse ApoAII following backcrosses with APOA2 Knockout mice (KO-ApoA2 described in ref. 1). KO-ApoA2 mice have been fully backcrossed into the C57BL/6 background before mating with human ApoAII transgenic mice. ApoAII is expressed only in liver. Its plasma concentration is 20-30 mg/dl with chow diet (physiological concentration in humans), and increases up to 50 mg/dl with a high fat diet. Mice present with normal plasma HDL levels and normal lipoprotein profile in the fed and fasted states (2).