Severe hypertriglyceridemia with plasma inhibitory factor(s) on lipoprotein lipase activity in a patient with a common Ser(447)-Ter LPL mutation

Severe hypertriglyceridemia is a major risk for acute pancreatitis. So far, several mutations on the lipoprotein lipase (LPL) gene causing type I hype rlipidemia have been identified. However, the common mutation Ser(447)-Ter has been recently proposed to have a lowering effect on serum triglyceride concentrations in the general population. In this study, we analyzed blood from a patient suffering from severe hypertriglyceridemia and pancreatitis with the mutation on the lipoprotein lipase gene, Ser(447)-Ter. The patient 's plasma showed inhibitory effects on the LPL activities from normal subje cts. The bottom fraction separated by ultracentrifugation revealed enhanced effects as an inhibitory factor. The inhibitory effect observed in the bot tom Fraction was dose-dependent, stable at treatment of 65 degreesC for 30 min, and decreased significantly after bring dialyzed using membranes with a cut-off molecular weight of 3500 or 6000 Da. The inhibitory effect was si gnificantly higher when the post-heparin plasma was used from the patient o r a subject with the same LPL mutation as an LPL source, compared to that f rom normal subjects. These results suggest that the patient has inhibitor): factors in his plasma. Such inhibitory Factors might cause severe hypertri glyceridemia in a case with the common mutation, which has been proposed to show the lowing effect on serum triglyceride concentrations in the general population. (C) 2001 Elsevier Science B.V. All rights reserved.