Serum C3 but not plasma acylation-stimulating protein is elevated in Finnish patients with familial combined hyperlipidemia

A trapping defect of fatty acids due to impaired function of acylation-stim ulating protein (ASP) has been suggested as one mechanism underlying the me tabolic abnormalities in familial combined hyperlipidemia (FCHL). The study aimed at defining the role of ASP and complement C3 in 35 Finnish FCHL fam ilies. There was no difference in plasma ASP levels between the 66 hypertri glyceridemic FCHL patients and their 84 normotriglyceridemic relatives. No response in plasma ASP could be observed after a fatty meal in 10 FCHL pati ents or in 10 control subjects. In familial correlation analyses, C3 exhibi ted a significant sibling-sibling correlation. The FCHL patients had higher serum C3 levels than their unaffected relatives (P<0.001). Furthermore, se rum C3 levels correlated significantly with several lipid parameters. The c orrelations between ASP and lipid variables were weaker than those of C3. T hese analyses suggest that common genes might contribute to the regulation of serum C3, triglycerides, HDL-C, free fatty acids, and insulin. The prese nt data do not support the hypothesis that defects of the ASP pathway are r eflected in plasma lipoproteins or in impaired plasma lipid clearance postp randially.