Article ID Journal Published Year Pages File Type
5985110 Journal of Clinical Lipidology 2016 12 Pages PDF
Abstract

•FCHL and elevated Lp(a) are inherited lipid disorders that may mimic FH.•FCHL and elevated Lp(a) are commonly encountered in mutation-negative FH patients.•FCHL co-expresses with components of the metabolic syndrome.•In mutation-negative FH, elevated Lp(a) is a contributor to increased coronary artery disease risk.

BackgroundA significant proportion of index cases presenting with phenotypic familial hypercholesterolemia (FH) are not found to have a pathogenic mutation and may have other inherited conditions.ObjectivesFamilial combined hyperlipidemia (FCHL) and elevated lipoprotein(a) [Lp(a)] may mimic FH, but the frequency and correlates of these disorders among mutation-negative FH patients have yet to be established.MethodsThe frequency of FCHL and elevated Lp(a) was investigated in 206 FH mutation-negative index cases attending a specialist lipid clinic. An FCHL diagnostic nomogram was applied to each index case; a positive diagnosis was made in patients with a probability score exceeding 90%. Plasma Lp(a) concentration was measured by immunoassay, with an elevated level defined as ≥0.5 g/L. Clinical characteristics, including coronary artery disease (CAD) events, were compared between those with and without FCHL and hyper-Lp(a).ResultsOf mutation-negative FH patients, 51.9% had probable FCHL. These patients were older (P = .002), had a higher BMI (P = .019) and systolic (P = .001) and diastolic blood pressures (P = .001) compared with those without FCHL. Elevated Lp(a) was observed in 44.7% of cases, and there were no significant differences in clinical characteristics with Lp(a) status. The presence of elevated Lp(a) (P = .002), but not FCHL, predicted CAD events. This association was independent of established CAD risk factors (P = .032).ConclusionFCHL and elevated Lp(a) are common disorders in patients with mutation-negative FH. Among such patients, FCHL co-expresses with components of the metabolic syndrome, and elevated Lp(a) is the major contributor to increased CAD risk.

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