Parabolic relation between plasma triglycerides and LDL-cholesterol in familial combined hyperlipidemia. The multiple-type hyperlipidemia explained?

Overview & Synopsis

Background: familial combined hyperlipdiemia (FCHL) is a highly prevalent genetic lipid disorder that accounts for a substantial number of premature cardiovascular events. To date, FCHL has been complicated by the different lipid phenotypes that are present within one family and one individual patient over time. Objective: in the present study, we hypothesized that a parabolic relation between plasma triglycerides and LDL-cholesterol can explain this so-called 'multiple-type hyperlipidemia' in FCHL. Methods: our hypothesis was tested in two well-documented FCHL cohorts (Maastricht: n=145; Nijmegen: n=299) that were followed over time with 5-years interval. Three groups were constructed depending on plasma triglycerides: group A (individuals with both measurement below 1.5 mmol/L), group B (one measurement below and one above 1.5 mmol/L) and group C (both measurement above 1.5 mmol/L). Results: in both male but not female cohorts, a significant, positive relation between plasma triglycerides and LDL-cholesterol was observed in group A (Maastricht: p=0.02; Nijmegen: p=0.001), a significant, negative relation in group C (Maastricht: p=0.01; Nijmegen: p=0.02), and a relation intermediate to group A and C in group B. In contrast, both apolipoprotein B levels and the prevalence of cardiovascular disease were related with plasma triglycerides in a more linear fashion. Conclusions: a parabolic relation between plasma triglycerides and LDL-cholesterol explains the 'multiple-type hyperlipidemia' in FCHL. In addition, the linear relation between triglycerides and both apolipoprotein B levels and prevalence of cardiovascular disease substantiate the use of apolipoprotein B instead of LDL-cholesterol in the diagnosis of FCHL and the prediction of cardiovascular disease.