Search

Purpose One of the major challenges in the management of familial hypercholesterolemia (FH) is the stratification of cardiovascular risk in asymptomatic subjects. Our purpose is to investigate the performance of clinical scoring systems, Montreal-FH-score (MFHS), SAFEHEART risk (SAFEHEART-RE) and FH risk score (FHRS) equations and Dutch Lipid Clinic Network (DLCN) diagnostic score, in predicting extent and severity of CAD at coronary computed tomography angiography (CCTA) in asymptomatic FH. Material and methods One-hundred and thirty-nine asymptomatic FH subjects were prospectively enrolled to perform CCTA. MFHS, FHRS, SAFEHEART-RE and DLCN were assessed for each patient. Atherosclerotic burden scores at CCTA (Agatston score [AS], segment stenosis score [SSS]) and CAD-RADS score were calculated and compared to clinical indices. Results Non-obstructive CAD was found in 109 patients, while 30 patients had a CAD-RADS ≥ 3. Classifying the two groups according to AS, values varied significantly for MFHS (p p p = 0.047), while according to SSS only MFHS and FHRS showed significant differences (p p MFHS proved to have the best discriminatory power (AUC = 0.819; 0.703–0.937, p p p Conclusions Greater values of MFHS, FHRS and SAFEHEART-RE are associated to higher risk of obstructive CAD and might help to select asymptomatic patients that should be referred to CCTA for secondary prevention.

Metabolic inflammation, defined as a chronic low-grade inflammation, is implicated in numerous metabolic diseases. In recent years, the role of regulatory T cells (Tregs) as key controllers of metabolic inflammation has emerged, but our comprehension on how different metabolic pathways influence Treg functions needs a deeper understanding. Here we focus on how circulating and intracellular lipid metabolism, in particular cholesterol metabolism, regulates Treg homeostasis, expansion, and functions. Cholesterol is carried through the bloodstream by circulating lipoproteins (chylomicrons, very low-density lipoproteins, low-density lipoproteins). Tregs are equipped with a wide array of metabolic sensors able to perceive and respond to changes in the lipid environment through the activation of different intracellular pathways thus conferring to these cells a crucial metabolic and functional plasticity. Nevertheless, altered cholesterol transport, as observed in genetic dyslipidemias and atherosclerosis, impairs Treg proliferation and function through defective cellular metabolism. The intracellular pathway devoted to the cholesterol synthesis is the mevalonate pathway and several studies have shown that this pathway is essential for Treg stability and suppressive activity. High cholesterol concentrations in the extracellular environment may induce massive accumulation of cholesterol inside the cell thus impairing nutrients sensors and inhibiting the mevalonate pathway. This review summarizes the current knowledge regarding the role of circulating and cellular cholesterol metabolism in the regulation of Treg metabolism and functions. In particular, we will discuss how different pathological conditions affecting cholesterol transport may affect cellular metabolism in Tregs.

Introduction: Angiopoietin-like protein 3 (ANGPTL3) and 4 (ANGPTL4) are regulators of triglycerides storage and utilization. Bariatric surgery (BS) determines profound changes in adipose tissue composition and energy metabolism. We evaluated the impact of BS on plasma levels of ANGPTL3 and ANGPTL4.Method: Twenty-seven morbidly obese subjects with or without type 2 diabetes (T2D) underwent Roux-en-Y gastric bypass (RYGB) and 18 patients with advanced T2D received Biliopancreatic Diversion (BPD). Fasting ANGPTLs levels, insulin sensitivity (evaluated by euglycemic hyperinsulinemic clamp), total bile acids (TBA) and free fatty acids (FFA) were measured at baseline and 1year after surgery.Results: Both surgical procedures resulted in fat mass loss, improved glucose control, and a ~2-fold increase of insulin sensitivity. ANGPTL4 levels decreased significantly with both RYGB (26.6 ± 0.6 to 24.4 ± 0.3 ng/mL, p=0.001) and BPD (27.9 ± 1.5 to 24.0 ± 0.5 ng/mL, p=0.003). In contrast, ANGPTL3 concentrations did not change after RYGB but rose following BPD (225 ± 20 to 300 ± 15 ng/mL, p=0.003). By multiple regression analysis, changes in ANGPTL4 were independently associated with those of blood glucose, p=0.0169) whereas changes in ANGPTL3 after BPD were associated with variations in FFA (p=0.008) and insulin sensitivity (p=0.0427). Discussion: Circulating ANGPTL4 is reduced by BS probably due to the loss of fat mass and improved insulin sensitivity. Conversely, ANGPTL3 levels increased after BPD, presumably because of the metabolic changes induced by the malabsorptive effect of this surgical procedure.

Individuals with loss-of-function mutations in the ANGPTL3 gene express a rare lipid phenotype called Familial Combined Hypolipidemia (FHBL2). FHBL2 individuals show reduced plasma concentrations of total cholesterol and triglycerides as well as of lipoprotein particles, including HDL. This feature is particularly remarkable in homozygotes in whom ANGPTL3 in blood is completely absent. ANGPTL3 acts as a circulating inhibitor of LPL and EL and it is thought that EL hyperactivity is the cause of plasma HDL reduction in FHBL2. Nevertheless, the consequences of ANGTPL3 deficiency on HDL functionality have been poorly explored. In this report, HDL isolated from homozygous and heterozygous FHBL2 individuals were evaluated for their ability to preserve endothelial homeostasis as compared to control HDL. It was found that only the complete absence of ANGPTL3 alters HDL subclass distribution, as homozygous, but not heterozygous, carriers have reduced content of large and increased content of small HDL with no alterations in HDL2 and HDL3 size. The plasma content of preβ-HDL was reduced in carriers and showed a positive correlation with plasma ANGPTL3 levels. Changes in composition did not however alter the functionality of FHBL2 HDL, as particles isolated from carriers retained their capacity to promote NO production and to inhibit VCAM-1 expression in endothelial cells. Furthermore, no significant changes in circulating levels of soluble ICAM-1 and E-selectin were detected in carriers. These results indicate that changes in HDL composition associated with the partial or complete absence of ANGPTL3 did not alter some of the potentially anti-atherogenic functions of these lipoproteins.

The effective reduction of LDL-C in patients with heterozygous familial hypercholesterolemia (HeFH) is crucial to reduce their increased cardiovascular risk. Diagnostic and therapeutic (PCSK9 inhibitors) tools to manage HeFH improved in recent years. However, the impact of these progresses in ameliorating the contemporary real-world care of these patients remains to be determined. Aim of this study was to assess the evolution of treatments and LDL-C control in a cohort of HeFH patients in Italy.Four hundred six clinically diagnosed HeFH followed in a single, tertiary lipid centre were included in this survey. Data on lipid levels and medications were collected at baseline and during a median 3-year follow-up. At baseline, 19.8% of patients were receiving conventional high-potency lipid lowering therapies (LLT) and this percentage increased up to 50.8% at last visit. The knowledge of results of molecular diagnosis was associated with a significant increase in treatment intensity and LDL-C lowering. Nevertheless, the new LDL-C target (70 mg/dl) was achieved only in 3.6% of HeFH patients under conventional LLTs and this proportion remained low (2.9%) also in those exposed to maximal conventional LLT. In 51 patients prescribed with PCSK9 inhibitors, 64.6% and 62.1% reached LDL-C70 mg/dl at 3- and 12-month follow-up, respectively.Although treatments of HeFH improved over time, LDL-C target achievement with conventional LLT remains poor, mainly among women. The use of molecular diagnosis and even more the prescription of PCSK9i may improve LDL-C control in these patients.

Angiopoietin-like 3 (ANGPTL3) regulates lipid and glucose metabolism. Loss-of-function mutations in its gene, leading to ANGPTL3 deficiency, cause in humans the familial combined hypolipidemia type 2 (FHBL2) phenotype, characterized by very low concentrations of circulating lipoproteins and reduced risk of atherosclerotic cardiovascular disease. Whether this condition is accompanied by immune dysfunctions is unknown. Regulatory T cells (Tregs) are CD4 T lymphocytes endowed with immune suppressive and atheroprotective functions and sensitive to metabolic signals. By investigating FHBL2, we explored the hypothesis that Tregs expand in response to extreme hypolipidemia, through a modulation of the Treg-intrinsic lipid metabolism.Treg frequency, phenotype, and intracellular lipid content were assessed ex vivo from FHBL2 subjects and age- and sex-matched controls, through multiparameter flow cytometry. The response of CD4 T cells from healthy controls to marked hypolipidemia was tested in vitro in low-lipid culture conditions.The ex vivo analysis revealed that FHBL2 subjects showed higher percentages of Tregs with a phenotype undistinguishable from controls and with a lower lipid content, which directly correlated with the concentrations of circulating lipoproteins. In vitro, lipid restriction induced the upregulation of genes of the mevalonate pathway, including those involved in isoprenoid biosynthesis, and concurrently increased the expression of the Treg markers FOXP3 and Helios. The latter event was found to be prenylation-dependent, and likely related to increased IL-2 production and signaling.Our study demonstrates that FHBL2 is characterized by high Treg frequencies, a feature which may concur to the reduced atherosclerotic risk in this condition. Mechanistically, hypolipidemia may directly favor Treg expansion, through the induction of the mevalonate pathway and the prenylation of key signaling proteins.

Little is known about the role of Lp(a) in the assessment of cardiovascular risk in the paediatric population. Trying to clarify the clinical relevance of Lp(a) in risk stratification, the aim of the study is to evaluate the association between Lp(a) plasma levels in children with familial hypercholesterolaemia (FH) and positive family history for premature cardiovascular disease (pCVD) in first- and second-degree relatives.653 Caucasian children and adolescents (334 females and 319 males), aged 2-17 years, with diagnosis of FH from a paediatric cohort included in the LIPIGEN Network, were selected. We compared family history of pCVD, lipid and genetic profile in two groups based on Lp(a) levels below or above 30 mg/dL. To determine the independent predictors of pCVD, a multivariate logistic regression was used, with all clinical characteristics and blood measurements as predictors.Subjects with Lp(a) 30 mg/dl more frequently reported positive family history of pCVD compared to subjects with Lp(a)≤30 mg/dl (69.90% vs 36.66%, p 0.0001), while did not show differences in terms of median [interquartile range] LDL-cholesterol level (153.00 [88.00 vs 164.50 [90.25] mg/dL, p = 0.3105). In the regression analysis, Lp(a) 30 mg/dl was an independent predictor of family history of pCVD. Comparing subjects with or without family history of pCVD, we reported significant differences for Lp(a) 30 mg/dl (46.25% vs 17.65%, p 0.0001), FH genetic mutation (50.48% vs 40.75%, p = 0,0157), as well as for LDL-cholesterol (p = 0.0013) and total cholesterol (p = 0.0101).Children/adolescents with FH and Lp(a) 30 mg/dl where more likely to have a positive family history of pCVD. Lp(a) screening in children and adolescents with FH may enhance risk assessment and help identify those subjects, children and relatives, at increased pCVD risk.

Background Familial hypercholesterolemia (FH) may arise from deleterious monogenic variants in FH‐causing genes as well as from a polygenic cause. We evaluated the relationships between monogenic FH and polygenic hypercholesterolemia in influencing the long‐term response to therapy and the risk of atherosclerosis. Methods and Results A cohort of 370 patients with clinically diagnosed FH were screened for monogenic mutations and a low‐density lipoprotein‐rising genetic risk score >0.69 to identify polygenic cause. Medical records were reviewed to estimate the response to lipid‐lowering therapies and the occurrence of major atherosclerotic cardiovascular events during a median follow‐up of 31.0 months. A subgroup of patients (n=119) also underwent coronary computed tomographic angiography for the evaluation of coronary artery calcium score and severity of coronary stenosis as compared with 135 controls. Two hundred nine (56.5%) patients with hypercholesterolemia were classified as monogenic (FH/M+), 89 (24.1%) as polygenic, and 72 (19.5%) genetically undefined (FH/M−). The response to lipid‐lowering therapy was poorest in monogenic, whereas it was comparable in patients with polygenic hypercholesterolemia and genetically undetermined. Mean coronary artery calcium score and the prevalence of coronary artery calcium >100 units were significantly higher in FH/M+ as compared with both FH/M− and controls. Finally, after adjustments for confounders, we observed a 5‐fold higher risk of incident major atherosclerotic cardiovascular events in FH/M+ (hazard ratio, 4.8; 95% CI, 1.06–21.36; P adj =0.041). Conclusions Monogenic cause of FH is associated with lower response to conventional cholesterol‐lowering therapies as well as with increased burden of coronary atherosclerosis and risk of atherosclerotic‐related events. Genetic testing for hypercholesterolemia is helpful in providing important prognostic information.

BACKGROUND The lack of functional evidence for most variants detected during the molecular screening of patients with clinical familial hypercholesterolemia (FH) makes the definitive diagnosis difficult. METHODS A total of 552 variants in LDLR, APOB, PCSK9 and LDLRAP1 genes found in 449 mutation-positive FH (FH/M+) patients were considered. Pathogenicity update was performed following the American College of Medical Genetics and Genomics (ACMG) guidelines with additional specifications on copy number variants, functional studies, in silico prediction and co-segregation criteria for LDLR, APOB and PCSK9 genes. Pathogenicity of LDLRAP1 variants was updated by using ACMG criteria with no change to original scoring. RESULTS After reclassification, the proportion of FH/M+ carriers of pathogenic (P) or likely pathogenic (LP) variants, and FH/M+ carriers of likely benign (LB) or benign (B) variants, was higher than that defined by standard criteria (81.5% vs. 79.7% and 7.1% vs. 2.7%). The refinement of pathogenicity classification also reduced the percentage of FH with variants of uncertain significance (VUS) (17.7% vs. 11.4%). After adjustment, the FH diagnosis by refined criteria best predicted LDL-C levels (Padj

Angiopoietin-like proteins, namely ANGPTL3-4-8, are known as regulators of lipid metabolism. However, recent evidence points towards their involvement in the regulation of adipose tissue function. Alteration of adipose tissue functions (also called adiposopathy) is considered the main inducer of metabolic syndrome (MS) and its related complications. In this review, we intended to analyze available evidence derived from experimental and human investigations highlighting the contribution of ANGPTLs in the regulation of adipocyte metabolism, as well as their potential role in common cardiometabolic alterations associated with adiposopathy. We finally propose a model of ANGPTLs-based adipose tissue dysfunction, possibly linking abnormalities in the angiopoietins to the induction of adiposopathy and its related disorders.

Background Autosomal recessive hypercholesterolemia (ARH) is a rare lipid disorder characterized by premature atherosclerotic cardiovascular disease (ASCVD). There are sparse data for clinical management and cardiovascular outcomes in ARH. Objectives Evaluation of changes in lipid management, achievement of low-density lipoprotein cholesterol (LDL-C) goals and cardiovascular outcomes in ARH. Methods Published ARH cases were identified by electronic search. All corresponding authors and physicians known to treat these patients were asked to provide follow-up information, using a standardized protocol. Results We collected data for 52 patients (28 females, 24 males; 31.1 ± 17.1 years of age; baseline LDL-C: 571.9 ± 171.7 mg/dl). During a mean follow-up of 14.1 ± 7.3 years, there was a significant increase in the use of high-intensity statin and ezetimibe in combination with lipoprotein apheresis; in 6 patients, lomitapide was also added. Mean LDL-C achieved at nadir was 164.0 ± 85.1 mg/dl (−69.6% from baseline), with a better response in patients taking lomitapide (−88.3%). Overall, 23.1% of ARH patients reached LDL-C of Conclusions Despite intensive treatment, LDL-C in ARH patients remains far from targets, and this translates into a poor long-term cardiovascular prognosis. Our data highlight the importance of an early diagnosis and treatment and confirm the fact that an effective treatment protocol for ARH is still lacking.

Purpose of review Angiopoietin-like protein-3 (ANGPTL3) is emerging as a key player in lipoprotein transport with an expanding role on fatty acid and glucose metabolism. Its deficiency is associated with a favorable metabolic profile. The present review will highlight the recent understanding of metabolic and cardiovascular consequences of ANGPTL3 inactivation by considering both genetic and pharmacological investigations. Recent findings Experimental studies have further illustrated the complex interplay between ANGPTL3 and ANGPTL4-8 in orchestrating lipid transport in different nutritional status. Individuals with familial combined hypolipidemia due to homozygous loss-of-function mutations in ANGPTL3 gene showed improved metabolism of triglyceride-rich lipoproteins during fasting and postprandial state and increased fatty acid oxidation and insulin sensitivity. Moreover, mendelian randomizations studies demonstrated that partial ANGPTL3 deficiency associates with reduced risk of atherosclerotic cardiovascular events and, eventually, diabetes mellitus. Finally, inactivation of ANGPTL3, using either a specific mAb or antisense oligonucleotide, was reported to reduce plasma levels of atherogenic lipoprotein in humans and improve hepatic fat infiltration in animal models. Summary Human and animal studies have further dissected the complex role of ANGPTL3 in the regulation of energy substrate metabolism. Moreover, genetic and pharmacological investigations have convincingly indicated that the inactivation of ANGPTL3 may be a very promising strategy to treat atherogenic metabolic disorders.

Objective: Familial chylomicronemia syndrome (FCS) and multifactorial chylomicronemia syndrome (MCS) are the prototypes of monogenic and polygenic conditions underlying genetically based severe hypertriglyceridemia. These conditions have been only partially investigated so that a systematic comparison of their characteristics remains incomplete. We aim to compare genetic profiles and clinical outcomes in FCS and MCS. Approach and Results: Thirty-two patients with severe hypertriglyceridemia (triglyceride >1000 mg/dL despite lipid-lowering treatments with or without history of acute pancreatitis) were enrolled. Rare and common variants were screened using a panel of 18 triglyceride-raising genes, including the canonical LPL , APOC2 , APOA5 , GP1HBP1 , and LMF1 . Clinical information was collected retrospectively for a median period of 44 months. Across the study population, 37.5% were classified as FCS due to the presence of biallelic, rare mutations and 59.4% as MCS due to homozygosity for nonpathogenic or heterozygosity for pathogenic variants in canonical genes, as well as for rare and low frequency variants in noncanonical genes. As compared with MCS, FCS patients showed a lower age of hypertriglyceridemia onset, higher levels of on-treatment triglycerides, and 3-fold higher incidence rate of acute pancreatitis. Conclusions: Our data indicate that the genetic architecture and natural history of FCS and MCS are different. FCS expressed the most severe clinical phenotype as determined by resistance to triglyceride-lowering medications and higher incidence of acute pancreatitis episodes. The most common genetic abnormality underlying FCS was represented by biallelic mutations in LPL while APOA5 variants, in combination with high rare polygenic burden, were the most frequent genotype of MCS.

The consequences of angiopoietin-like protein 3 (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 h after a high fat meal. Postprandial lipid and lipoprotein changes were quantified by calculating the areas under the curve (AUCs) using the 6 h concentration data. Plasma changes of β-hydroxybutyric acid (β-HBA) were measured as marker of hepatic oxidation of fatty acids. Compared with controls, homozygotes showed lower incremental AUCs (iAUCs) 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 the iAUC 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 the postprandial FFA pool, and decreased influx of dietary-derived fatty acids into the liver. These results add information on mechanisms underlying hypolipidemia in FHBL2.

Loss-of-function (LOF) mutations in ANGPTL3, an inhibitor of lipoprotein lipase (LPL), cause a drastic reduction of serum lipoproteins and protect against the development of atherosclerotic cardiovascular disease. Therefore, ANGPTL3 is a promising therapy target. We characterized the impacts of ANGPTL3 depletion on the immortalized human hepatocyte (IHH) transcriptome, lipidome and human plasma lipoprotein lipidome. The transcriptome of ANGPTL3 knock-down (KD) cells showed altered expression of several pathways related to lipid metabolism. Accordingly, ANGPTL3 depleted IHH displayed changes in cellular overall fatty acid (FA) composition and in the lipid species composition of several lipid classes, characterized by abundant n-6 and n-3 polyunsaturated FAs (PUFAs). This PUFA increase coincided with an elevation of lipid mediators, among which there were species relevant for resolution of inflammation, protection from lipotoxic and hypoxia-induced ER stress, hepatic steatosis and insulin resistance or for the recovery from cardiovascular events. Cholesterol esters were markedly reduced in ANGPTL3 KD IHH, coinciding with suppression of the SOAT1 mRNA and protein. ANGPTL3 LOF caused alterations in plasma lipoprotein FA and lipid species composition. All lipoprotein fractions of the ANGPTL3 LOF subjects displayed a marked drop of 18:2n-6, while several highly unsaturated triacylglycerol (TAG) species were enriched. The present work reveals distinct impacts of ANGPTL3 depletion on the hepatocellular lipidome, transcriptome and lipid mediators, as well as on the lipidome of lipoproteins isolated from plasma of ANGPTL3-deficient human subjects. It is important to consider these lipidomics and transcriptomics findings when targeting ANGPTL3 for therapy and translating it to the human context.

ObjectiveLoss-of-function variants in the angiopoietin-like 3 gene (ANGPTL3) have been associated with low levels of plasma lipoproteins and decreased coronary artery disease risk. We aimed to determine detailed metabolic effects of genetically-induced ANGPTL3 deficiency in fasting and postprandial state.Approach and ResultsWe studied individuals carrying S17X loss-of-function mutation in ANGPTL3 (6 homozygous and 32 heterozygous carriers) and 38 noncarriers. Nuclear magnetic resonance metabolomics was used to quantify 225 circulating metabolic measures. We compared metabolic differences between loss-of-function carriers and noncarriers in fasting state and after a high fat meal. In fasting, ANGPTL3 deficiency was characterized by similar extent of reductions in low-density lipoprotein cholesterol (0.74 SD-units lower concentration per loss-of-function allele [95%CI 0.42–1.06]) as observed for many triglyceride-rich lipoprotein measures, including very-low-density lipoprotein cholesterol (0.75 [0.45–1.05]). Within most lipoprotein subclasses, absolute levels of cholesterol were decreased more than triglycerides, resulting in the relative proportion of cholesterol being reduced within triglyceride-rich lipoproteins and their remnants. Further, beta-hydroxybutyrate was elevated (0.55 [0.21–0.89]). Homozygous ANGPTL3 loss-of-function carriers showed essentially no postprandial increase in triglyceride-rich lipoproteins and fatty acids, without evidence for adverse compensatory metabolic effects.ConclusionsIn addition to overall triglyceride and low-density lipoprotein cholesterol lowering effects, ANGPTL3 deficiency results in reduction of cholesterol proportion within triglyceride-rich lipoproteins and their remnants. Further, ANGPTL3 loss-of-function carriers had elevated ketone body production, suggesting enhanced hepatic fatty acid beta-oxidation. The detailed metabolic profile in human knockouts of ANGPTL3 reinforces inactivation of ANGPTL3 as a promising therapeutic target for decreasing cardiovascular risk.HIGHLIGHTSANGPTL3 deficiency results in similar reductions in LDL cholesterol and many triglyceride-rich lipoprotein lipids measures, such as VLDL cholesterol, with no evidence of substantial adverse effects on the comprehensive panel of circulating metabolite biomarkers tested here.In particular, ANGPTL3 deficiency results in reduction of cholesterol content in triglyceride-rich lipoproteins and their remnants, which have been highlighted as risk factor for cardiovascular disease independently of LDL levels.Homozygous ANGPTL3 loss-of-function carriers show essentially no postprandial increase in triglyceride-rich lipoproteins and fatty acids in response to a fat challenge, and display consistently elevated postprandial levels of ketone bodies and lactate when compared to noncarriers, suggesting enhanced hepatic fatty acid beta-oxidation.

Objective To evaluate the effectiveness of criteria based on child-parent assessment in predicting familial hypercholesterolemia (FH)-causative mutations in unselected children with hypercholesterolemia. Study design LDLR, APOB , and PCSK9 genes were sequenced in 78 children and adolescents (mean age 8.4 ± 3.7 years) with clinically diagnosed FH. The presence of polygenic hypercholesterolemia was further evaluated by genotyping 6 low-density lipoprotein cholesterol (LDL-C)-raising single-nucleotide polymorphisms. Results Thirty-nine children (50.0%) were found to carry LDLR mutant alleles but none with APOB or PCSK9 mutant alleles . Overall, 27 different LDLR mutations were identified, and 2 were novel. Children carrying mutations showed higher LDL-C (215.2 ± 52.7 mg/dL vs 181.0 ± 44.6 mg/dL, P .001) and apolipoprotein B levels (131.6 ± 38.3 mg/dL vs 100.3 ± 30.0 mg/dL, P .004), compared with noncarriers. A LDL-C of ~190 mg/dL was the optimal value to discriminate children with and without LDLR mutations. When different diagnostic criteria were compared, those proposed by the European Atherosclerosis Society showed a reasonable balance between sensitivity and specificity in the identification of LDLR mutations. In children without mutation, the FH phenotype was not caused by the aggregation of LDL-C raising single-nucleotide polymorphisms. Conclusions In unselected children with hypercholesterolemia, LDL-C levels >190 mg/dL and a positive family history of hypercholesterolemia appeared to be the most reliable criteria for detecting FH. As 50% of children with suspected FH did not carry FH-causing mutations, genetic testing should be considered.

Background The most frequent monogenic causes of low plasma cholesterol are familial hypobetalipoproteinemia (FHBL1) because of truncating mutations in apolipoprotein B coding gene (APOB) and familial combined hypolipidemia (FHBL2) due to loss-of-function mutations in ANGPTL3 gene. Objective A direct comparison of lipid phenotypes of these 2 conditions has never been carried out. In addition, although an increased prevalence of liver steatosis in FHBL1 has been consistently reported, the hepatic consequences of FHBL2 are not well established. Methods We investigated 350 subjects, 67 heterozygous carriers of APOB mutations, 63 carriers of the p.S17* mutation in ANGPTL3 (57 heterozygotes and 6 homozygotes), and 220 noncarrier normolipemic controls. Prevalence and degree of hepatic steatosis were assessed by ultrasonography. Results A steady decrease of low-density lipoprotein cholesterol levels were observed from heterozygous to homozygous FHBL2 and to FHBL1 individuals, with the lowest levels in heterozygous FHBL1 carrying truncating mutations in exons 1 to 25 of APOB (P for trend

Familial combined hypolipidemia causes a global reduction of plasma lipoproteins. Its clinical correlates and metabolic implications have not been well defined.The objective of the study was to investigate the genetic, clinical, and metabolic characteristics of a cohort of subjects with familial combined hypolipidemia.The design of the study included candidate gene screening and the comparison of the clinical and metabolic characteristics between carrier and noncarrier individuals.The study was conducted in a general community.Participants in the study included individuals belonging to nine families with familial combined hypolipidemia identified in a small town (Campodimele) as well as from other 352 subjects living in the same community.Serum concentrations of lipoproteins, Angiopoietin-like 3 (Angptl3) proteins, and noncholesterol sterols were measured.The ANGPTL3 S17X mutation was found in all probands, 20 affected family members, and 32 individuals of the community. Two additional frame shift mutations, FsE96del and FsS122, were also identified in two hypocholesterolemic individuals. Homozygotes for the ANGPTL3 S17X mutation had no circulating Angptl3 and a marked reduction of all plasma lipids (P0.001). Heterozygotes had 42% reduction in Angptl3 level compared with noncarriers (P0.0001) but a significant reduction of only total cholesterol and high-density lipoprotein cholesterol. No differences were observed in the plasma noncholesterol sterols between carriers and noncarriers. No association between familial combined hypolipidemia and the risk of hepatic or cardiovascular diseases were detected.Familial combined hypolipidemia segregates as a recessive trait so that apolipoprotein B- and apolipoprotein A-I-containing lipoproteins are comprehensively affected only by the total deficiency of Angptl3. Familial combined hypolipidemia does not perturb whole-body cholesterol homeostasis and is not associated with adverse clinical sequelae.

Background Defective low-density lipoprotein receptor ( LDLR ) and lipoprotein lipase ( LPL ) alleles have been implicated in familial combined hyperlipidemia (FCHL). However, their contribution might have been influenced by diagnostic criteria. This study was aimed to reassess the frequency of rare and common variants in LDLR and LPL in FCHL individuals classified with stringent criteria. Methods LDLR and LPL were resequenced in 208 FHCL and 171 controls. Variants were classified as loss- (LOF) or gain-of-function (GOF) based upon in silico prediction, familial segregation and available functional data. Results Eight LOF variants were detected in LDLR , 6 of which were missense and 2 were predicted to disrupt normal splicing; all were present at heterozygous state. They were found in 10 FCHL but not in controls, thus indicating that 4.8% of FCHL individuals should be reclassified as FH. LDL-C (positive) and BMI (negative) were the strongest predictors of LDLR mutations with LDL-C 181 mg/dl being the best threshold for diagnosing the presence of dysfunctional LDLR alleles. The cumulative prevalence of definite LPL defective alleles (1 rare and 2 common heterozygous missense variants) was comparable between FCHL and controls (10.1% vs. 10.5%). Conversely, the LPL GOF variant p.Ser474* showed a lower frequency in FCHL than in controls (13.5% vs. 24.0%, p = 0.008). Overall, LOF LPL variants did not show a TG-modulating effect. Conclusions Our findings indicate that, in well characterized FCHL individuals, variants in LDLR and LPL provide a small contribution to this dyslipidemia, thus limiting the need for such genetic testing.

The role of adipose triglyceride lipase (ATGL) in intermediate substrates metabolism has not been fully elucidated in humans.Our objective was to evaluate the consequences of ATGL deficiency on body fat distribution, insulin sensitivity, fatty acids metabolism, and energy substrate utilization.Body composition and organ fat content were measured by bioimpedance and (1)H nuclear magnetic resonance spectroscopy; heart glucose metabolism by [(18)F]deoxyglucose positron emission tomography and insulin sensitivity and β-cell function by oral glucose tolerance and 2-step euglycemic-hyperinsulinemic clamp. Lipolysis ([(2)H5]glycerol turnover) and indirect calorimetry were evaluated at fasting, after oral glucose load, during the clamp, and also during an iv epinephrine infusion. These metabolic investigations were carried out during hospitalization.Three patients affected by neutral lipid storage disease with myopathy (NLSDM) due to homozygosity for loss-of-function mutations in the ATGL gene and 6 sex-, age-, and body mass index-matched controls were studied.As expected, NLSDM patients showed diffuse, although heterogeneous, fat infiltration in skeletal muscles associated with increased visceral fat. Although heart and liver were variably affected, fat content in the pancreas was increased in all patients. Compared with healthy controls, NLSDM patients showed impaired insulin response to glucose possibly related to the severe pancreatic steatosis, preserved whole-body insulin sensitivity, and a shift toward glucose metabolism in the heart. Fasting nonesterified fatty acid concentrations as well as basal lipolytic rates and the antilipolytic effect of insulin were normal in NLSDM patients, whereas the lipolytic effect of norepinephrine was impaired. Finally, no significant abnormality in the respiratory quotient was noted in NLSDM patients.In humans, ATGL has a remarkable effect on cellular lipid droplet handling, and its lack causes both perivisceral, skeletal muscle, and pancreas fat accumulation; in contrast, the impact on whole-body insulin sensitivity and fatty acid metabolism is minor.

double-blind crossover study of omega-3 and omega-6 fatty acids. Am J Clin Nutr 1991;53:562–72. [40] Lungershausen YK, Abbey M, Nestel PJ, et al. Reduction of blood pressure and plasma triglycerides by omega-3 fatty acids in treated hypertensives. J Hypertens 1994;12:1041–6. [41] Suzukawa M, Abbey M, Howe P, et al. Effects of fish oil fatty acids on low density lipoprotein size, oxidizability, and uptake by macrophages. J Lipid Res 1995;36:473–84. [42] Gans RO, Bilo HJ, Weersink EG, et al. Fish oil supplementation in patients with stable claudication. Am J Surg 1990;160:490–5. [43] Tanaka K, Ishikawa Y, Yokoyama M, et al. Reduction in the recurrence of stroke by eicosapentaenoic acid for hypercholesterolemic patients subanalysis of the JELIS trial. Stroke 2008;39:2052–8. [44] Fuchs J, Beigel Y, Green P, et al. Big platelets in hyperlipidemic patients. J Clin Pharmacol 1992;32:639–42. [45] Aucamp A, Schoeman H, Coetzee J. Pilot trial to determine the efficacy of a low dose of fish oil in the treatment of angina pectoris in the geriatric patient. Prostaglandins Leukot Essent Fatty Acids 1993;49:687–9. [46] Sirtori CR, Paoletti R, Mancini M, et al. n−3 fatty acids do not lead to an increased diabetic risk in patients with hyperlipidemia and abnormal glucose tolerance. Italian Fish Oil Multicenter Study. Am J Clin Nutr 1997;65:1874–81. [47] Petersen M, Pedersen H, Major-Pedersen A, et al. Effect of fish oil versus corn oil supplementation on LDL and HDL subclasses in type 2 diabetic patients. Diabetes Care 2002;25:1704–8. [48] Thies F, Garry J, Yaqoob P, et al. Association of n−3 polyunsaturated fatty acids with stability of atherosclerotic plaques: a randomised controlled trial. Lancet 2003;361:477–85. [49] Grundt H, Nilsen DW, Mansoor MA, et al. Reduction in homocysteine by n−3 polyunsaturated fatty acids after 1 year in a randomised double-blind study following an acute myocardial infarction: no effect on endothelial adhesion properties. Pathophysiol Haemost Thromb 2003;33:88–95. [50] Nilsen DW, Albrektsen G, Landmark K, et al. Effects of a high-dose concentrate of n−3 fatty acids or corn oil introduced early after an acute myocardial infarction on serum triacylglycerol and HDL cholesterol. Am J Clin Nutr 2001;74:50–6.

Cumulating evidence are revealing roles of angiopoietin-like proteins (ANGPTLs) in lipid, glucose, and energy metabolism. In this review, we discuss the recent developments in understanding the specific role in metabolic processes of the liver-derived ANGPTL3.Several groups have reported clinical and metabolic characterization of individuals with loss-of-function variants in ANGPTL3 showing familial combined hypolipidemia, a syndrome characterized by marked reduction of all plasma lipoproteins. Their findings indicate that in humans, ANGPTL3 has a broader action on apoB and apoA-I-containing lipoproteins, as well as on free fatty acid and adipose tissue metabolism.The identification of loss-of-function ANGPTL3 mutation is shedding light on a possible role of ANGPTL3 at the crossroads of lipoproteins, fatty acids, and glucose metabolism, thus making ANGPTL3 an attractive protein to target the cardio-metabolic risk.

Familial combined hyperlipidemia (FCHL) has been associated with abnormalities in fatty acid metabolism. The adipose triglyceride lipase (PNPLA2) plays a pivotal role in the turnover of fatty acids in adipose tissue and liver. This study was designed to evaluate whether selected PNPLA2 variants may influence the susceptibility to FCHL or its lipid-related traits.Four SNPs within the PNPLA2 gene (rs7925131, rs7942159, rs66460720 and the nonsynonymous P481L) were selected based on previous association with decreased plasma levels of free fatty acids (FFA) and total triglycerides (TG) and their high frequency (MAF0.25). These SNPs were genotyped in 214 FCHL individuals from 83 families and in 103 controls and the corresponding haplotypes were reconstructed.No association between individual SNPs and the FCHL trait was observed. However, two PNPLA2 haplotypes were associated with lower risk of FCHL (P0.004 after Bonferroni's correction). Compared to the others, these haplotypes were related to lower TG (118.9 ± 66.8 vs. 197.1 ± 114.7 mg/dl; P=0.001) and higher HDL-C (62.3 ± 15.8 vs. 51.0 ± 15.0 mg/dl; P0.005). In a subgroup of studied subjects (n=63) protective haplotypes were also associated with lower FFA levels (0.33 ± 0.11 vs. 0.46 ± 0.18 mEq/L; P0.05). These effects were independent from age, BMI and HOMA(IR).These data demonstrate that variants within PNPLA2 may modulate the TG component of FCHL trait, thus implicating PNPLA2 as modifier gene in this lipid disorder. They also suggest a potential role of PNPLA2 in the metabolism of TG-rich lipoproteins.

Background A significant proportion of individuals clinically diagnosed with familial hypercholesterolemia (FH), but without any disease-causing mutation, are likely to have polygenic hypercholesterolemia. We evaluated the distribution of a polygenic risk score, consisting of 12 low-density lipoprotein cholesterol (LDL-C)-raising variants (polygenic LDL-C risk score), in subjects with a clinical diagnosis of FH. Methods and Results Within the Lipid Transport Disorders Italian Genetic Network (LIPIGEN) study, 875 patients who were FH-mutation positive (women, 54.75%; mean age, 42.47±15.00 years) and 644 patients who were FH-mutation negative (women, 54.21%; mean age, 49.73±13.54 years) were evaluated. Patients who were FH-mutation negative had lower mean levels of pretreatment LDL-C than patients who were FH-mutation positive (217.14±55.49 versus 270.52±68.59 mg/dL, P