beta(2)-glycoprotein I deficiency: prevalence, genetic background and effects on plasma lipoprotein metabolism and hemostasis

beta(2)-glycoprotein I (beta(2)-GPI = apolipoprotein H) is an important aut oantigen in patients with the antiphospholipid syndrome. It also plays a ro le in lipoprotein metabolism, such as anti-atherogenic property, triglyceri de removal, and enhancement of lipoprotein lipase. Serum beta(2)-GPI concen tration of 812 apparently healthy Japanese individuals was measured by sand wich EIA. Two families with complete beta(2)-GPI deficiency were identified . In one family, all affected had increased serum LDL-cholesterol levels or smaller particle sizes of LDL, while the other had no apparent abnormality in lipid metabolism. Individuals investigated had no history of thrombosis or overt abnormalities in hemostatic tests. A thymine corresponding to pos ition 379 of the beta(2)-GPI cDNA was deleted in every beta(2)-GPI deficien t individual. The incidence of this heterozygous deficiency determined by R FLP was 6.3% in Japanese and none in Caucasians. Heterozygotes had signific antly lower concentrations of serum beta(2)-GPI than did those without the mutation, yet no significantly different lipid profiles, such as total chol esterol, triglyceride, HDL-cholesterol, LDL-cholesterol, apoA-I, apoB and L p(a), were observed. A low concentration of beta(2)-GPI seemed not to be as sociated with apparent abnormality in lipoprotein metabolism. (C) 2000 Else vier Science Ireland Ltd. All rights reserved.