This 2023 statement updates clinical guidance for homozygous familial hypercholesterolaemia (HoFH), explains the genetic complexity, and provides pragmatic recommendations to address inequities in HoFH care worldwide. Key strengths include updated criteria for the clinical diagnosis of HoFH and the recommendation to prioritize phenotypic features over genotype. Thus, a low-density lipoprotein cholesterol (LDL-C) >10 mmol/L (>400 mg/dL) is suggestive of HoFH and warrants further evaluation. The statement also provides state-of-the art discussion and guidance to clinicians for interpreting the results of genetic testing and for family planning and pregnancy. Therapeutic decisions are based on the LDL-C level. Combination LDL-C-lowering therapy—both pharmacologic intervention and lipoprotein apheresis (LA)—is foundational. Addition of novel, efficacious therapies (i.e. inhibitors of proprotein convertase subtilisin/kexin type 9, followed by evinacumab and/or lomitapide) offers potential to attain LDL-C goal or reduce the need for LA. To improve HoFH care around the world, the statement recommends the creation of national screening programmes, education to improve awareness, and management guidelines that account for the local realities of care, including access to specialist centres, treatments, and cost. This updated statement provides guidance that is crucial to early diagnosis, better care, and improved cardiovascular health for patients with HoFH worldwide.

Familial chylomicronaemia syndrome (FCS) is a rare, inherited disorder characterised by impaired clearance of triglyceride (TG)-rich lipoproteins from plasma, leading to severe hypertriglyceridaemia (HTG) and a markedly increased risk of acute pancreatitis. It is due to the lack of lipoprotein lipase (LPL) function, resulting from recessive loss of function mutations in the genes coding LPL or its modulators. A large overlap in the phenotype between FCS and multifactorial chylomicronaemia syndrome (MCS) contributes to the inconsistency in how patients are diagnosed and managed worldwide, whereas the incidence of acute hypertriglyceridaemic pancreatitis is more frequent in FCS. A panel of European experts provided guidance on the diagnostic strategy surrounding FCS and proposed an algorithm-based diagnosis tool for identification of these patients, which can be readily translated into practice. Features included in this FCS score comprise: severe elevation of plasma TGs (fasting TG levels >10 mmol/L [885 mg/dL] on multiple occasions), refractory to standard TG-lowering therapies, a young age at onset, the lack of secondary factors (except for pregnancy and oral oestrogens) and a history of episodes of acute pancreatitis. Considering 53 FCS patients from three cohorts and 52 MCS patients from three cohorts, the overall sensitivity of the FCS score (≥10) was 88% (95% confidence interval [CI]: 0.76, 0.97) with an overall specificity of 85% (95% CI: 0.75, 0.94). Receiver operating characteristic curve area was 0.91. Pragmatic clinical scoring, by standardising diagnosis, may help differentiate FCS from MCS, may alleviate the need for systematic genotyping in patients with severe HTG and may help identify high-priority candidates for genotyping.

Familial chylomicronemia syndrome (FCS) is an ultra-rare phenotype that is usually caused by biallelic mutations in the LPL gene encoding lipoprotein lipase, or less often in APOC2, APOA5, LMF1, or GPIHBP1 genes encoding cofactors or interacting proteins. We evaluated baseline phenotypes among FCS participants in a phase 3 randomized placebo-controlled trial of volanesorsen (NCT02211209). Baseline clinical, fasting, and postfat load metabolic markers were assessed. Targeted next-generation DNA sequencing plus custom bioinformatics was used to genotype subjects. Among 52 FCS individuals, 41 had biallelic LPL gene mutations (LPL-FCS patients): 82%, 7%, and 11% were missense, nonsense, and splicing variants, respectively. Eleven individuals had non-LPL-FCS; 2 had mutations in APOA5, 5 in GPIHBP1, and 1 each in LMF1 and APOC2 genes, respectively. Two other individuals were double heterozygotes, each with 1 normal LPL allele. All subjects had extremely high triglycerides (TGs) and chylomicrons, but very low levels of other lipoproteins. Compared with LPL-FCS individuals, non-LPL-FCS individuals were very similar for most traits, but had significantly higher postheparin LPL activity, higher 4-hour postprandial insulin and C-peptide levels; and higher low-density lipoprotein cholesterol levels. In non-LPL-FCS individuals compared to those with LPL-FCS, there were also nonsignificant trends toward lower levels of total and chylomicron TGs, lower 4-hour postprandial chylomicron TG levels, and higher very-low-density lipoprotein TG levels. Thus, LPL FCS and non-LPL FCS are largely phenotypically similar. However, LPL FCS patients have lower postheparin LPL activity and a trend toward higher TGs, whereas low-density lipoprotein cholesterol was higher in non-LPL-FCS patients.

Background: Evidence regarding the relationships among high plasma triglycerides (TG), all‐cause mortality, and atherosclerotic cardiovascular disease (ASCVD) events in low‐to‐moderate risk individuals is limited. The aim of this study was to determine whether the presence of high TG levels influences the risk of all‐cause mortality and ASCVD events in a population cohort followed in the real‐world clinical setting. Methods and Results: A retrospective longitudinal cohort analysis using administrative databases of 3 Italian Local Health Units was performed. All individuals with at least one TG measurement between January 1, 2010 and December 31, 2015 were followed through December 2016. Outcome measures included incident ASCVD events and all‐cause mortality. Individuals with normal TG levels (500 mg/dL). 158 042 individuals (142 289 with normal, 15 558 with high, and 195 with very high TG) were considered. In the whole cohort, the overall incidence rates of ASCVD and all‐cause mortality were 7.2 and 17.1 per 1000 person‐years, respectively. After multivariate adjustment for potential confounders, individuals with high and very high TG showed a significantly increased risk of all‐cause mortality (hazard ratio [HR]=1.49 [95% confidence interval (CI) 1.36–1.63], P <0.001, and HR=3.08 [95% CI 1.46–6.50], P <0.01, respectively) and incident ASCVD events (HR=1.61 [95% CI 1.43–1.82], P <0.001, and HR=2.30 [95% CI 1.02–5.18], P <0.05, respectively) as compared to those with normal TG. Conclusions: Moderate‐to‐severe elevation of TG is associated with a significantly increased risk of all‐cause mortality and ASCVD events in a large cohort of low‐to‐moderate cardiovascular risk individuals in a real‐world clinical setting.

The consequences of ANGPTL3 deficiency on postprandial lipid and lipoprotein metabolism has not been investigated in humans. We studied 7 homozygous (undetectable circulating ANGPTL3 levels) and 31 heterozygous (50% of circulating ANGPTL3 levels) subjects with familial combined hypolipidemia (FHBL2) due to inactivating ANGPTL3 mutations in comparison with 35 controls. All subjects were evaluated at fasting and during 6 hours after a high fat meal. Postprandial lipid and lipoprotein changes were quantified by calculating the areas under the curve (AUC) using the 6h concentration data. Plasma changes of β-hydroxybutyric acid (β-HBA) were measured as marker of hepatic oxidation of fatty acids. Compared to controls, homozygotes showed lower incremental AUC of total TG (-69%, P<0.001), TG-rich lipoproteins (-90%, P<0.001), apoB-48 (-78%; P=0.032) and larger absolute increase of FFA (+128%; P<00.1). Also heterozygotes displayed attenuated postprandial lipemia, but the difference was significant only for incremental AUC of apoB-48 (-28%; P<0.05). During the postprandial period, homozygotes, but not heterozygotes, showed a lower increase of β-HBA. Our findings demonstrate that complete ANGPTL3 deficiency associates with highly reduced postprandial lipemia probably due to faster catabolism of intestinally derived lipoproteins, larger expansion of postprandial FFA pool and decreased influx of dietary-derived fatty acids into the liver. These results add information on mechanisms underlying hypolipidemia in FHBL2.