Martina Ferrandino

High levels of low-density lipoprotein cholesterol (LDL-c) have been recognized as the main causal factor of atherosclerotic cardiovascular disease (ASCVD) and are influenced by both genetic and environmental factors. Among genetic determinants, Familial Hypercholesterolemia (FH) is the most common monogenic disorder, caused by rare high-impact variants in genes involved in LDL uptake. Other monogenic causes of hypercholesterolemia include sitosterolemia, cerebrotendinous xanthomatosis and lysosomal acid lipase deficiency (LALD). However, monogenic disorders only account for a small proportion of inherited hypercholesterolemia. In many individuals, increased LDL-c levels are caused by the contemporary presence of different single-nucleotide polymorphisms (SNPs) with a moderate/low impact. These SNPs could be summarized through polygenic risk scores (PRS) that attribute relative weight to each of these. Another genetic determinant of hypercholesterolemic phenotypes is high levels of lipoprotein(a)—Lp(a). Lp(a) is an LDL particle modified by the binding of apolipoprotein(a)—apo(a)—which represents an independent risk factor for ASCVD. Lp(a) levels are mainly genetically determined by variation in the number of kringle IV type 2 (K-IV₂) repeats, as well as by several SNPs, and remain stable throughout life. The aim of this narrative review is to report an updated overview of the genetic mechanisms underlying hypercholesterolemia, including monogenic disorders, PRS and Lp(a), focusing on their potential repercussion in clinical practice by the integration into cardiovascular risk stratification beyond traditional clinical assessment. This integration could lead to a more comprehensive and individualized approach to cardiovascular prevention, with emerging perspectives including the possible use of artificial intelligence (AI).

Background: Heterozygous familial hypercholesterolemia (HeFH) is characterized by elevated low-density lipoprotein cholesterol (LDL-C) and increased cardiovascular risk, making early diagnosis essential; however, the diagnostic performance of pediatric criteria is heterogeneous. This study evaluated the effectiveness of different diagnostic criteria and scoring systems to select children for genetic testing. Materials and methods: A total of 214 pediatric subjects with suspected HeFH were included, recruited from patients followed at a tertiary care center, based on LDL-C levels ≥ 95th age- and sex-specific percentile in both the proband and one biological parent. All subjects underwent genetic analysis of the main FH-associated genes (LDLR, APOB, PCSK9). The following diagnostic criteria and scoring systems were retrospectively evaluated and compared with genetic findings: Simon Broome Register (SBR), Dutch Lipid Clinic Network (DLCN), European Atherosclerosis Society (EAS), American Heart Association (AHA), Familial Hypercholesterolemia Canada Network (FH-CAN), Japanese Atherosclerosis Society (JAS), Lipid TransPort Disorders Italian Genetic Network for Italian pediatric patients (LIPIGEN-FH-PED), and the Familial Hypercholesterolemia Pediatric Diagnostic Score (FH-PeDS). Results: Pathogenic variants were identified in 91.8% of subjects. Approaches using lower LDL-C thresholds minimized the loss of variant-positive individuals (particularly JAS and FH-PeDS, with a missed diagnoses rate of 1.6%), whereas more restrictive definitions excluded a substantial proportion of affected patients (10.5% SBR, 56.3% DLCN, 6.3% EAS, 6.3% AHA, 7.4% FH-CAN, and 6.3% LIPIGEN-FH-PED). The mutation detection rate (MDR) was >91% for all examined criteria. Conclusions: Several current diagnostic criteria may underestimate the true number of children carrying FH-associated variants. Less selective criteria enable the identification of a greater number of FH-positive individuals while maintaining a high MDR, thus supporting the prioritization of identifying as many affected children as possible in the pediatric setting. This cohort reflects a tertiary referral population rather than the general population; therefore, further studies are needed to evaluate the applicability of our findings to broader public health contexts and screening settings.

Familial Hypercholesterolemia (FH) is a common genetic disorder characterized by elevated LDL-cholesterol levels and an increased risk of premature cardiovascular disease. While pathogenic variants in LDLR, APOB, and PCSK9 are well-established causes, a substantial proportion of clinically suspected FH cases do not carry either pathogenic variants or rare variants of uncertain significance in these genes (FH/V−/USV−). This study aimed to characterize the metabolome/lipidome of genetically confirmed heterozygous FH (HeFH) patients compared to FH/V−/USV−, seeking to identify specific alterations associated with genetic status and phenotypic variability. Untargeted high-resolution mass spectrometry (UHPLC-Q-Exactive-MS)-based lipidomics and nuclear magnetic resonance-based metabolomics were performed on plasma samples of FH patients (n = 20 HeFH and n = 19 FH/V−/USV−) towards healthy controls (n = 22). PLS-DA analysis revealed group-level separation, suggesting differences in the circulating metabolome/lipidome. As expected, most of identified lipid classes were higher in both FH groups compared to normolipidemic controls. Notably, significant lipids (VIP > 1, p < 0.05) showed potential in distinguishing HeFH and FH/V−/USV− patients, particularly sphingomyelins. These data were confirmed by multivariable regression analysis controlling for age, sex, and lipid-lowering therapy as well as by ROC analysis. The evidence of a distinct lipidome signature in the HeFH subgroup may relate to the increased cardiovascular risk of HeFH patients compared to patients without pathogenic variants.