A Caucasian male with very low blood cholesterol and low apoA-II without evidence of atherosclerosis

Background: It is well known that a high level of apolipoprotein (apo) A-II can be associated with familial combined hyperlipidaemia, and that high apolipoprotein profiles can contribute to the development of atherosclerosis. The serum lipoprotein/apolipoprotein profile of a Caucasian patient who had unusually low serum total cholesterol (83 mg dL) and triglyceride (28 mg dL) levels despite a high body mass index (33.5 kg m ), is the subject of this report. Materials and methods: Each lipoprotein was isolated from serum by sequential ultracentrifugation, and serum and lipoprotein lipids and proteins were determined. The cholesteryl ester (CE) conversion ability of lecithin:cholesterol acyltransferase and CE transfer activity of CE transfer protein were assayed, and the composition of apolipoprotein and lipoprotein was analyzed by electrophoresis and Western blot analysis. Results: Electrophoresis and immunodetection analyses revealed a 60% decrease in the apoA-II band intensity compared to normal reference serum. The decreased apoA-II was associated with reduced very low density lipoprotein-cholesterol and protein content, as well as a greater high-density lipoprotein (HDL) size with high cholesterol content. The CE conversion activity and CE transfer activity of HDL were almost totally lacking in the hypolipidaemic serum, although the expression level of lecithin:cholesterol acyltransferase was normal. Electron microscopy revealed that the obese patient had larger HDL and HDL particle sizes than those of reference serum. Conclusion: These results suggest that a decreased apoA-II protein in serum and increased HDL-cholesterol and particle size might protect against hyperlipidaemia and the atherosclerotic process, even in a patient with severe obesity. © 2007 The Authors.