β2-glycoprotein I gene deficiency (β2GPI-Sapporo) and the progression of atherosclerosis

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Recent evidence suggested that antiphospholipid antibodies may have contributed to the formation of atherosclerotic lesions. In SLE less than 45 years of age, myocardial infarction has been recognized as a major cause of mortality. I have reported that aCL found in patients with antiphospholipid syndrome (APS) are not simply directed to the CL structure, but require the presence of β2-glycoprotein I (β2GPI) for bindng and that the epitopes is expressed by conformational changes occurring whenβ2GPI interacts with an oxygen-substituted solid surface. Β2GPI specifically bound to oxidized LDL and oxidized lipoproteins in the blood, especially oxidized LDL, are also sequentially targeted by β2GPI and aCL, and that immunoreaction is involved not only in the metabolism of plasma lipoproteins but also in thrombotic complications accompanied by atherosclerotic events in APS.Serumβ2GPI concentration of 812 apparently healthy Japanese individuals was measured by sandwich EIA. Two families with completeβ2GPI deficiency were identified. A thymine corresponding to position 379 of the β2GPI cDNA was deleted in every β2GPI deficient individual. The incidence of this heterozygous deficiency determined by RFLP was 6.3% in Japanese and none in Caucasians Heterozygotes had significantly lower concentrations of serumβ2GPI than did those without the mutation, yet no significantly different lipid profiles, such as total cholesterol, triglyceride, HDL-cholesterol, LDL-cholesterol, apoA-I, apoB and Lp(a), were observed. A low concentration ofβ2GPI seemed not to be associated with apparent abnormality in lipoprotein metabolism.