Evidence against alterations in Lecithin:cholesterol acyltransferase (LCAT) activity in Familial combined hyperlipidemia

Elevated concentrations of plasma cholesterol and triglycerides are characteristic of familial combined hyperlipidemia (FCHL) which may also present with reduced high density lipoprotein (HDL) cholesterol concentrations. Lecithin:cholesterol acyltransferase (LCAT) plays a key role in reverse cholesterol transport by converting unesterified cholesterol to cholesterol ester in the process of maturation of HDL in the presence of its activator, apolipoprotein (apo) A-I. We hypothesised that alterations in LCAT activity or plasma concentrations or gene sequence of apo A-I could influence HDL metabolism in these patients. We studied cholesterol concentrations of high density lipoprotein subfractions and LCAT activity in 25 FCHL subjects and 48 controls. Total HDL ( p=0.018) and HDL2 ( p=0.008) were significantly decreased in the FCHL group compared with controls. After analyses with adjusted data only HDL2 remained significantly decreased in the FCHL group ( p=0.050). The LDLc/HDLc and A-I/HDLc ratios were significantly elevated in the FCHL group ( p