– Apolipoprotein A1 (APOA1) is a secreted protein which belongs to the Apolipoprotein A1/A4/E family. APOA1 is the major protein component of high density lipoprotein (HDL) in plasma. APOA1 plays a critical role in various biological processes, such as Cholesterol metabolism, Lipid metabolism and transport, Steroid metabolism. APOA1 promotes cholesterol efflux from tissues to the liver and thus helps to clear cholesterol from arteries. Defects in this gene resulted in HDL deficiencies, including Tangier disease (TGD), systemic non-neuropathic amyloidosis, premature coronary artery disease, hepatosplenomegaly and progressive muscle wasting and weakness. In addition, ApoA-I is implicated in the anti-endotoxin function of HDL via interaction with lipopolysaccharide or endotoxin.