LAUSR

BACKGROUND Familial hypercholesterolemia (FH) in children is under-detected. Plasma biomarkers associated with low-density lipoprotein receptor (LDLR) function could help identifying FH children. OBJECTIVES We aim to assess the clinical value of inducible degrader of the LDLR (IDOL), soluble LDLR (sLDLR), and proprotein convertase subtilisin/kexin type 9 (PCSK9) plasma concentrations in children with FH compared with control children (CCh). METHODS This was a cross-sectional study performed in a Lipid Unit from a University hospital. The participants were 177 children distributed into FH (n = 77) and CCh (n = 100). Main outcomes were changes in IDOL, sLDLR, and PCSK9 plasma concentrations between children groups; secondary outcomes were the association between IDOL, sLDLR, and PCSK9 and lipid profile determined by 2-dimensional nuclear magnetic resonance. RESULTS The IDOL levels were higher in FH compared with CCh (P = .007). The PCSK9 levels were elevated in FH (P < .001). The sLDLR levels had no significant differences between groups. IDOL was significantly positively associated to total and LDL cholesterol and ApoB100 but not to LDL particle number. However, a robust correlation with Lp(a) (P = .001) was observed. PCSK9 had the strongest correlation with LDL-associated parameters including particle number. sLDLR was associated with triglyceride levels (P < .001) and triglyceride-rich particles and inversely to LDL size. CONCLUSIONS The IDOL and PCSK9 plasma levels are significantly higher in FH children. Interestingly, sLDLR was associated with atherogenic dyslipidemia components. IDOL concentrations show a robust association with Lp(a) levels. To study the role of plasma biomarkers associated with LDLR expression in FH is warranted.