Background/Aims Metabolic dysfunction-associated steatotic liver disease (MASLD) may progress to liver inflammation, fibrosis, cirrhosis and hepatocellular carcinoma. So far, genome-wide association studies explain a small fraction of MASLD heritability. Methods We sought to identify novel genetic determinants of MASLD by exploring interactions between genetic variants and body mass index (BMI). First, we examined genome-wide interactions with BMI for circulating alanine aminotransferase (ALT) levels using UK Biobank data. For identified loci, we next examined associations with hepatic proton density fat fraction (PDFF) in 35,146 independent UK Biobank participants. Associations with PDFF were replicated in four independent European cohorts, followed by a phenome-wide association study. Finally, we used human liver epigenomic maps and CRISPR/Cas9 experiments in vitro and in vivo to functionally characterize the CYP7A1 locus. Results Thirteen loci interact with BMI for ALT (P<5E-8), including eight well-known genetic modulators of MASLD. Two loci—UBXN2B/CYP7A1 and GIPR—are additionally associated with PDFF. For the intronic rs34783010 in GIPR, the minor T allele is associated with lower BMI and higher HbA1c and liver triglyceride content in humans. The UBXN2B/CYP7A1 locus is associated with PDFF in four additional European cohorts. Epigenomic data and in vitro experiments in human liver cells prioritise rs10504255 and CYP7A1 as the functional effectors in this locus. Perturbation of CYP7A1 orthologues using CRISPR/Cas9 results in less liver fat in 10-day-old, metabolically challenged zebrafish larvae. Conclusions A genome-wide single nucleotide polymorphism×BMI design fuelled identification of two MASLD genes: CYP7A1 and GIPR.

Background/Aims Metabolic dysfunction-associated steatotic liver disease (MASLD) is a global epidemic. The disease has a strong genetic component, and a common missense variant (rs2642438) in the mitochondrial amidoxime-reducing component 1 (MARC1) gene confers protection against its onset and severity. However, there are contrasting results regarding the mechanisms that promote this protection. Methods We downregulated MARC1 in primary human hepatocytes (PHHs) using short interfering RNA (siRNA). We measured neutral lipid content by Oil-Red O staining and fatty acid oxidation by radiolabeled tracers. We also performed RNA-sequencing and proteomic analysis using LC-MS. Additionally, we analyzed data from 239,075 participants from the UK Biobank. Results Downregulation of MARC1 reduced neutral lipid content in PHHs homozygous for the wild type (p.A165, risk), but not for the mutant (p.T165, protective), allele. We found that this reduction was mediated by increased fatty acid utilization via β-oxidation. Consistent with these results, we found that the levels of 3-hydroxybutyrate, a by-product of β-oxidation, were higher in carriers of the rs2642438 minor allele among samples from the UK biobank, indicating higher β-oxidation in these individuals. Moreover, downregulation of the MARC1 p.A165 variant resulted in a more favorable phenotype by reducing ferroptosis and reactive oxygen species levels. Conclusions MARC1 downregulation in carriers of the risk allele results in lower hepatocyte neutral lipids content due to higher β-oxidation, while upregulating beneficial pathways involved in cell survival.

Objective :Metabolic dysfunction-associated steatotic liver disease (MASLD) is a global health concern with no effective and specific drug treatment available. The rs2642438 minor allele in mitochondrial amidoxime-reducing component 1 (MARC1) results in an aminoacidic substitution (p.Ala165Thr) and associates with protection against MASLD. However, the mechanisms behind this protective effect are unknown. In this study, we examined the consequences of this aminoacidic substitution on protein stability and subcellular localization. Methods :We overexpressed the human MARC1 A165 (wild-type) or 165T (mutant) in vivo in mice and in vitro in human hepatoma cells (HepG2 and HuH-7), generated several mutants at position 165 by in situ mutagenesis and then examined protein levels. We also generated HepG2 cells stably overexpressing MARC1 A165 or 165T to test the effect of this substitution on MARC1 subcellular localization. Results :MARC1 165T overexpression resulted in lower protein levels than A165 both in vivo and in vitro. Similarly, any mutant at position 165 showed lower protein levels compared to the wild-type protein. We showed that the 165T mutant protein is polyubiquitinated and its degradation is accelerated through lysine-48 ubiquitin-mediated proteasomal degradation. We also showed that the 165T substitution does not affect the MARC1 subcellular localization. Conclusions :This study shows that alanine at position 165 in MARC1 is crucial for protein stability, and the threonine substitution at this position leads to a hypomorphic protein variant due to lower protein levels. Our result supports the notion that lowering hepatic MARC1 protein level may be a successful therapeutic strategy for treating MASLD.

Steatotic liver disease (SLD) prevails as the most common chronic liver disease yet lack approved treatments due to incomplete understanding of pathogenesis. Recently, elevated hepatic and circulating interleukin 32 (IL -32) levels were found in individuals with severe SLD. However, the mechanistic link between IL -32 and intracellular triglyceride metabolism remains to be elucidated. We demonstrate in vitro that incubation with IL -32b protein leads to an increase in intracellular triglyceride synthesis, while downregulation of IL32 by small interfering RNA leads to lower triglyceride synthesis and secretion in organoids from human primary hepatocytes. This reduction requires the upregulation of Phospholipase A2 group IIA (PLA2G2A). Furthermore, downregulation of IL32 results in lower intracellular type I collagen levels in di -lineage human primary hepatic organoids. Finally, we identify a genetic variant of IL32 (rs76580947) associated with lower circulating IL -32 and protection against SLD measured by non-invasive tests. These data suggest that IL32 downregulation may be beneficial against SLD.

BACKGROUND:ANGPTL3 (angiopoietin-like protein 3) is a circulating protein with a key role in maintaining lipoprotein homeostasis. A monoclonal antibody against ANGPTL3 is an approved and well-tolerated treatment to reduce lipoproteins in familial hypercholesterolemia homozygotes. However, the reduction of hepatic ANGPTL3 synthesis using an antisense oligonucleotide unexpectedly resulted in a dose-dependent increase in liver lipid content and circulating transaminases, resulting in the termination of the clinical trial. Meanwhile, the use of silencing RNAs remains an area of active investigation. Our study sought to investigate whether intracellular downregulation of ANGPTL3 may lead to a primary increase in neutral lipids within the hepatocyte. METHODS:We downregulated ANGPTL3 by silencing RNA in primary human hepatocytes 3-dimensional spheroids, HepG2/LX-2 3-dimensional spheroids, and in HepG2, Hep3B2, and Huh7 cultured in 2 dimensions. RESULTS:ANGPTL3 downregulation increased neutral lipids in all models investigated. Interestingly, ANGPTL3 induced lower intracellular deiodinase type 1 protein levels resulting in a reduction in beta-oxidation and causing an increase in triglycerides stored in lipid droplets. CONCLUSIONS:In conclusion, intracellular ANGPTL3 downregulation by silencing RNA led to an increase in triglycerides content due to a reduction in energy substrate utilization resembling a primary intracellular hepatocyte hypothyroidism.

In the submitted and accepted version of this paper, five author names were omitted in error. These authors were: Ville Männistö, Jussi Pihlajamäki, Sami Qadri, Hannele Yki-Järvinen, Stefano Romeo. The correct author and affilitation list is provided in this corrigendum. We apologise for any inconvenience caused.

BACKGROUND/AIMS:Metabolic dysfunction-associated steatotic liver disease (MASLD) is a global epidemic. The disease has a strong genetic component, and a common missense variant (rs2642438) in the mitochondrial amidoxime-reducing component 1 (MARC1) gene confers protection against its onset and severity. However, there are contrasting results regarding the mechanisms that promote this protection. METHODS:We downregulated MARC1 in primary human hepatocytes (PHHs) using short interfering RNA (siRNA). We measured neutral lipid content by Oil-Red O staining and fatty acid oxidation by radiolabeled tracers. We also performed RNA-sequencing and proteomic analysis using LC-MS. Additionally, we analyzed data from 239,075 participants from the UK Biobank. RESULTS:Downregulation of MARC1 reduced neutral lipid content in PHHs homozygous for the wild type (p.A165, risk), but not for the mutant (p.T165, protective), allele. We found that this reduction was mediated by increased fatty acid utilization via β-oxidation. Consistent with these results, we found that the levels of 3-hydroxybutyrate, a by-product of β-oxidation, were higher in carriers of the rs2642438 minor allele among samples from the UK biobank, indicating higher β-oxidation in these individuals. Moreover, downregulation of the MARC1 p.A165 variant resulted in a more favorable phenotype by reducing ferroptosis and reactive oxygen species levels. CONCLUSION:MARC1 downregulation in carriers of the risk allele results in lower hepatocyte neutral lipids content due to higher β-oxidation, while upregulating beneficial pathways involved in cell survival.

BACKGROUND & AIMS: Noninvasive assessment of histological features of nonalcoholic fatty liver disease (NAFLD) has been an intensive research area over the last decade. Herein, we aimed to develop a simple noninvasive score using routine laboratory tests to identify, among individuals at high risk for NAFLD, those with fibrotic nonalcoholic steatohepatitis (NASH) defined as NASH, NAFLD activity score & GE;4, and fibrosis stage & GE;2.METHODS: The derivation cohort included 264 morbidly obese individuals undergoing intraoperative liver biopsy in Rome, Italy. The best predictive model was developed and internally validated using a bootstrapping stepwise logistic regression analysis (2000 bootstrap samples). Performance was estimated by the area under the receiver operating characteristic curve (AUROC). External validation was assessed in 3 independent European cohorts (Finland, n = 370; Italy, n = 947; England, n = 5368) of individuals at high risk for NAFLD. RESULTS: The final predictive model, designated as Fibrotic NASH Index (FNI), combined aspartate aminotransferase, high-density lipoprotein cholesterol, and hemoglobin A1c. The performance of FNI for fibrotic NASH was satisfactory in both derivation and external validation cohorts (AUROC = 0.78 and AUROC = 0.80-0.95, respectively). In the derivation cohort, rule-out and rule-in cutoffs were 0.10 for sensitivity & GE;0.89 (negative predictive value, 0.93) and 0.33 for specificity & GE;0.90 (positive predictive value, 0.57), respectively. In the external validation co-horts, sensitivity ranged from 0.87 to 1 (negative predictive value, 0.99-1) and specificity from 0.73 to 0.94 (positive predictive value, 0.12-0.49) for rule-out and rule-in cutoff, respectively.CONCLUSION: FNI is an accurate, simple, and affordable noninvasive score which can be used to screen for fibrotic NASH in individuals with dysmetabolism in primary health care.

Fatty liver disease (FLD) is a growing health issue with burdening unmet clinical needs. FLD has a genetic component but, despite the common variants already identified, there is still a missing heritability component. Using a candidate gene approach, we identify a locus (rs71519934) at the Pleckstrin and Sec7 domain-containing 3 ( PSD3 ) gene resulting in a leucine to threonine substitution at position 186 of the protein (L186T) that reduces susceptibility to the entire spectrum of FLD in individuals at risk. PSD3 downregulation by short interfering RNA reduces intracellular lipid content in primary human hepatocytes cultured in two and three dimensions, and in human and rodent hepatoma cells. Consistent with this, Psd3 downregulation by antisense oligonucleotides in vivo protects against FLD in mice fed a non-alcoholic steatohepatitis-inducing diet. Thus, translating these results to humans, PSD3 downregulation might be a future therapeutic option for treating FLD.

Background & Aims: Sirtuin 5, encoded by the SIRT5 gene, is a NAD+ -dependent deacylase that modulates mitochondrial metabolic processes through post-translational modifications. In this study, we aimed to examine the impact of the SIRT5 rs12216101 T>G non-coding single nucleotide polymorphism on disease severity in patients with non-alcoholic fatty liver disease (NAFLD). Methods: The rs12216101 variant was genotyped in 2,606 consecutive European patients with biopsy-proven NAFLD. Transcriptomic analysis, expression of mitochondrial complexes and oxidative stress levels were measured in liver samples from a subset of bariatric patients. Effects of SIRT5 pharmacological inhibition were evaluated in HepG2 cells exposed to excess free fatty acids. Mitochondrial energetics in vitro were investigated by high-performance liquid chromatography. Results: In the whole cohort, the frequency distribution of SIRT5 rs12216101 TT, TG and GG genotypes was 47.0%, 42.3% and 10.7%, respectively. At multivariate logistic regression analysis adjusted for sex, age >50 years, diabetes, and PNPLA3 rs738409 status, the SIRT5 rs12216101 T>G variant was associated with the presence of non-alcoholic steatohepatitis (odds ratio 1.20, 95% CI 1.03-1.40) and F2-F4 fibrosis (odds ratio 1.18; 95% CI 1.00-1.37). Transcriptomic analysis showed that the SIRT5 rs12216101 T>G variant was associated with upregulation of transcripts involved in mitochondrial metabolic pathways, including the oxidative phosphorylation system. In patients carrying the G allele, western blot analysis confirmed an upregulation of oxidative phosphorylation complexes III, IV, V and consistently higher levels of reactive oxygen species, reactive nitrogen species and malondialdehyde, and lower ATP levels. Administration of a pharmacological SIRT5 inhibitor preserved mitochondrial energetic homeostasis in HepG2 cells, as evidenced by restored ATP/ADP, NAD+/NADH, NADP+/NADPH ratios and glutathione levels. Conclusions: The SIRT5 rs12216101 T>G variant, heightening SIRT5 activity, is associated with liver damage, mitochondrial dysfunction, and oxidative stress in patients with NAFLD. (c) 2023 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.

The ultrasound‐based controlled attenuation parameter (CAP) is a non‐invasive tool widely validated for assessing liver steatosis across different etiologies. However, few studies, with liver biopsy available, have investigated its performance in individuals with morbid obesity. Herein, we aimed to evaluate the diagnostic accuracy of CAP in participants with morbid obesity from the MAFALDA study before bariatric surgery.

Background & Aims: Non-alcoholic fatty liver disease (NAFLD) is the leading cause of liver disorders and has a strong heritable component. The aim of this study was to identify new loci that contribute to severe NAFLD by examining rare variants.Methods: We performed whole-exome sequencing in in-dividuals with NAFLD and advanced fibrosis or hepatocellular carcinoma (n = 301) and examined the enrichment of likely pathogenic rare variants vs. the general population. This was followed by validation at the gene level.Results: In patients with severe NAFLD, we observed an enrichment of the p.P426L variant (rs143545741 C>T; odds ratio [OR] 5.26, 95% CI 2.1-12.6; p = 0.003) of autophagy-related 7 (ATG7), which we characterized as a loss-of-function, vs. the general population, and an enrichment in rare variants affecting the catalytic domain (OR 13.9; 95% CI 1.9-612; p = 0.002). In the UK Biobank cohort, loss-of-function ATG7 variants increased the risk of cirrhosis and hepatocellular carcinoma (OR 3.30; 95% CI 1.1-7.5 and OR 12.30, 95% CI 2.6-36, respectively; p <0.001 for both). The low-frequency loss-of-function p.V471A variant (rs36117895 T>C) was also associated with severe NAFLD in the clinical cohort (OR 1.7; 95% CI 1.2-2.5; p = 0.003), predisposed to hepatocellular ballooning (p = 0.007) evolving to fibrosis in the Liver biopsy cohort (n = 2,268), and was associated with liver injury in the UK Biobank (aspartate aminotransferase levels, p <0.001), with a larger effect in severely obese in-dividuals in whom it was linked to hepatocellular carcinoma (p = 0.009). ATG7 protein localized to periportal hepatocytes, particularly in the presence of ballooning. In the Liver Tran-scriptomic cohort (n = 125), ATG7 expression correlated with suppression of the TNFa pathway, which was conversely upregulated in p.V471A carriers.Conclusions: We identified rare and low-frequency ATG7 loss-of -function variants that promote NAFLD progression by impairing autophagy and facilitating ballooning and inflammation.Lay summary: We found that rare mutations in a gene called autophagy-related 7 (ATG7) increase the risk of developing severe liver disease in individuals with dysmetabolism. These mutations cause an alteration in protein function and impairment of self -renewal of cellular content, leading to liver damage and inflammation.(c) 2022 The Authors. Published by Elsevier B.V. on behalf of European Association for the Study of the Liver. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/ licenses/by-nc-nd/4.0/).

BACKGROUND & AIMS:Fatty liver disease (FLD) is a growing epidemic that is expected to be the leading cause of end-stage liver disease within the next decade. Both environmental and genetic factors contribute to the susceptibility of FLD. Several genetic variants contributing to FLD have been identified in exome-wide association studies. However, there is still a missing hereditability indicating that other genetic variants are yet to be discovered.METHODS:To find genes involved in FLD, we first examined the association of missense and nonsense variants with alanine aminotransferase at an exome-wide level in 425,671 participants from the UK Biobank. We then validated genetic variants with liver fat content in 8930 participants in whom liver fat measurement was available, and replicated 2 genetic variants in 3 independent cohorts comprising 2621 individuals with available liver biopsy.RESULTS:We identified 190 genetic variants independently associated with alanine aminotransferase after correcting for multiple testing with Bonferroni method. The majority of these variants were not previously associated with this trait. Among those associated, there was a striking enrichment of genetic variants influencing lipid metabolism. We identified the variants rs2792751 in GPAM/GPAT1, the gene encoding glycerol-3-phosphate acyltransferase, mitochondrial, and rs429358 in APOE, the gene encoding apolipoprotein E, as robustly associated with liver fat content and liver disease after adjusting for multiple testing. Both genes affect lipid metabolism in the liver.CONCLUSIONS:We identified 2 novel genetic variants in GPAM and APOE that are robustly associated with steatosis and liver damage. These findings may help to better elucidate the genetic susceptibility to FLD onset and progression.

Abstract Abstract: Non-alcoholic fatty liver disease (NAFLD) is currently the most common liver disease worldwide, paralleling the epidemic of obesity and type 2 diabetes. Despite the high prevalence of NAFLD, only a minority of patients progress to NASH and advanced fibrosis. The reasons for this inter-individual variability are not completely understood but can be partially accounted for by genetic risk factors (1). Although several common genetic variants associated with liver disease have been identified, there is still a proportion of NAFLD heritability that remains unknown. The rare rs143545741 C>T variant in the autophagy related 7 (ATG7) gene (P426L) has been associated with a higher risk of progressive NAFLD (2). Interestingly, ATG7 encodes a E1-like ubiquitin activating enzyme which is involved in hepatic lipophagy (3). We hypothesized that the unknown heritability of NAFLD might be partially explained by rare genetic variants, therefore not identified in the GWAS studies. Moreover, we assumed that loss-of-function variants in ATG7 might confer an increased susceptibility to NAFLD by reducing autophagic catabolism of lipid droplets in the liver. To examine the underlying mechanism of the low-frequency V471A variant and the rare T86I, L127I, Q170E, and P426L variants in ATG7, we performed in vitro experiments of HepaRG cells overexpressing the human V5-tagged ATG7. We observed a reduction in intracellular lipid content in HepaRG cells overexpressing the ATG7 wild type and the 86I mutant protein (p=0.029, n=4) but not the 127I, 170E, 426L, and 471A mutant proteins. Cells with the ATG7 127I, 170E, 426L, and 471A mutants had higher intracellular lipid content compared to cells overexpressing the wild type protein (p=0.029, n=4). Our data suggested that the low-frequency V471A variant and the rare L127I, Q170E, and P426L variants in ATG7 are loss-of-function, resulting in defective lipophagy, reduced hepatocellular lipid droplets turnover, and excessive lipid accumulation. More experiments are needed to clarify the underlying mechanism of the T86I variant. In conclusion, we highlighted a role for ATG7 in reducing hepatocellular lipid content. Furthermore, we provided evidence showing non-synonymous variants in ATG7 increase the risk of NAFLD and that these variants are loss-of-function. We speculate that ATG7 might be a new susceptibility risk genetic locus for liver disease development and progression. References: (1) Eslam et al. J Hepatol. 2018;68(2):268–279. (2) Baselli et al. The Liver Meeting 2018 - AASLD. Hepatology. October 2018. Volume 68, Issue S1. (3) Martinez-Lopez and Singh. Annu Rev Nutr. 2015;35:215–37.

Chronic liver disease, with viral or non-viral etiology, is endemic in many countries and is a growing burden in Asia. Among the Asian countries, Pakistan has the highest prevalence of chronic liver disease. Despite this, the genetic susceptibility to chronic liver disease in this country has not been investigated. We performed a comprehensive analysis of the most robustly associated common genetic variants influencing chronic liver disease in a cohort of individuals from Pakistan. A total of 587 subjects with chronic liver disease and 68 healthy control individuals were genotyped for the HSD17B13 rs7261356, MBOAT7 rs641738, GCKR rs1260326, PNPLA3 rs738409, TM6SF2 rs58542926 and PPP1R3B rs4841132 variants. The variants distribution between case and control group and their association with chronic liver disease were tested by chi-square and binary logistic analysis, respectively. We report for the first time that HSD17B13 variant results in a 50% reduced risk for chronic liver disease; while MBOAT7; GCKR and PNPLA3 variants increase this risk by more than 35% in Pakistani individuals. Our genetic analysis extends the protective role of the HSD17B13 variant against chronic liver disease and disease risk conferred by the MBOAT7; GCKR and PNPLA3 variants in the Pakistani population.

OBJECTIVE:Nonalcoholic fatty liver disease (NAFLD) is becoming a leading cause of advanced chronic liver disease. The progression of NAFLD, including nonalcoholic steatohepatitis (NASH), has a strong genetic component, and the most robust contributor is the patatin-like phospholipase domain-containing 3 (PNPLA3) rs738409 encoding the 148M protein sequence variant. We hypothesized that suppressing the expression of the PNPLA3 148M mutant protein would exert a beneficial effect on the entire spectrum of NAFLD. METHODS:We examined the effects of liver-targeted GalNAc3-conjugated antisense oligonucleotide (ASO)-mediated silencing of Pnpla3 in a knock-in mouse model in which we introduced the human PNPLA3 I148M mutation. RESULTS:ASO-mediated silencing of Pnpla3 reduced liver steatosis (p = 0.038) in homozygous Pnpla3 148M/M knock-in mutant mice but not in wild-type littermates fed a steatogenic high-sucrose diet. In mice fed a NASH-inducing diet, ASO-mediated silencing of Pnpla3 reduced liver steatosis score and NAFLD activity score independent of the Pnpla3 genotype, while reductions in liver inflammation score (p = 0.018) and fibrosis stage (p = 0.031) were observed only in the Pnpla3 knock-in 148M/M mutant mice. These responses were accompanied by reduced liver levels of Mcp1 (p = 0.026) and Timp2 (p = 0.007) specifically in the mutant knock-in mice. This may reduce levels of chemokine attracting inflammatory cells and increase the collagenolytic activity during tissue regeneration. CONCLUSION:This study provides the first evidence that a Pnpla3 ASO therapy can improve all features of NAFLD, including liver fibrosis, and suppress the expression of a strong innate genetic risk factor, Pnpla3 148M, which may open up a precision medicine approach in NASH.

The precursors of atherogenic dyslipidemia (AD) are not well defined. Therefore, we investigated 62 non-obese, non-diabetic AD and 221 normolipemic children. Anthropometric parameters, blood pressure and biochemical measures were obtained in index children, their parents and all available siblings. The heritability (h2) of anthropometric and biochemical traits was estimated by SOLAR. Rare and common variants in APOA1 and LPL genes were screened by re-sequencing. Compared to normolipemic, AD children showed increased body mass index, waist circumference, plasma glucose, insulin, ApoB, HOMA-IR, hs-CRP and lower adiponectin (p<0.001 for all). Metabolic syndrome was present in 40% of AD while absent in controls. All traits (except adiponectin and hs-CRP) showed a strong familial aggregation, with plasma glucose having the highest heritability (89%). Overall, 4 LPL loss-of-function mutations were detected (p.Asp9Asn, p.Ser45Asn, p.Asn291Ser, p.Leu365Val) and their cumulative prevalence was higher in AD than in control children (0.073 vs. 0.026; P=0.038). The LPL p.S447* gain-of-function mutation, resulted to be less frequent in AD than in control children (0.064 vs. 0.126; P=0.082). No variant in the APOA1 gene was found. Our data indicate that AD is a rather common dyslipidemia in childhood; it associates with metabolic abnormalities typical of insulin resistant state and shows a strong familial aggregation. LPL variants may contribute to the development of AD phenotype.

[This corrects the article DOI: 10.1371/journal.pone.0120099.].

Familial combined hypolipidemia (FHBL2, OMIM #605019) is a recently identified low-cholesterol syndrome characterized by a peculiar lipid profile where both pro-atherogenic [very low density (VLDL) and low density (LDL)] and anti-atherogenic [high density (HDL)] lipoproteins are reduced [ [1] Musunuru K. Pirruccello J.P. Do R. et al. Exome sequencing, ANGPTL3 mutations, and familial combined hypolipidemia. N Engl J Med. 2010; 363: 2220-2227 Crossref PubMed Scopus (489) Google Scholar ]. It is caused by loss-of-function (LOF) mutations in the ANGPTL3 gene determining the absence or the marked reduction of ANGPTL3 protein in the plasma [ 2 Pisciotta L. Favari E. Magnolo A.L. et al. Characterization of three kindred with familial combined hypolipidemia due to loss of function mutations of ANGPTL3. Cardiovasc Genet. 2012; 5: 42-50 Crossref PubMed Scopus (99) Google Scholar , 3 Noto D. Cefalù A.B. Valenti V. et al. Prevalence of ANGPTL3 and APOB gene mutations in subjects with combined hypolipidemia. Arterioscler Thromb Vasc Biol. 2012; 32: 805-809 Crossref PubMed Scopus (65) Google Scholar , 4 Martín-Campos J.M. Roig R. Mayoral C. et al. Identification of a novel mutation in the ANGPTL3 gene in two families diagnosed of familial hypobetalipoproteinemia without APOB mutation. Clin Chim Acta. 2012; 413: 552-555 Crossref PubMed Scopus (49) Google Scholar , 5 Minicocci I. Montali A. Robciuc M.R. et al. Mutations in the ANGPTL3 gene and familial combined hypolipidemia: a clinical and biochemical characterization. J Clin Endocrinol Metab. 2012; 97: E1266-E1275 Crossref PubMed Scopus (94) Google Scholar ]. The simultaneous reduction of pro- and anti-atherogenic lipoproteins raises the question whether FHBL2 affects the risk of atherosclerosis. Previous observations in apoE-deficient mice suggested that the reduction of ANGPTL3 protects against atherosclerosis [ [6] Ando Y. Shimizugawa T. Takeshita S. et al. A decreased expression of angiopoietin-like 3 is protective against atherosclerosis in apoE-deficient mice. J Lipid Res. 2003; 44: 1216-1223 Crossref PubMed Scopus (75) Google Scholar ], but no data are available in FHBL2. This leaves the issue of role of ANGPTL3 in atherogenesis in humans still open. Nevertheless, FHBL2 offers the unique opportunity to evaluate the impact on the vasculature of life-long exposure to low HDL in the context of unusually low levels of apoB-containing (VLDL and LDL) atherogenic lipoproteins.