The Genetic Basis of Hypertriglyceridemia

Targeting apolipoprotein C-III: a game changer for pancreatitis prevention in severe hypertriglyceridemia

PURPOSE OF REVIEW

The aim of this review is to examine recent advancements in RNA-targeted therapies for the management of severe hypertriglyceridemia (sHTG) and prevention of sHTG-associated acute pancreatitis.

RECENT FINDINGS

Recent developments in RNA-targeted therapies, aimed at inhibiting apolipoprotein C-III (apoC-III), have demonstrated substantial and sustained reductions in triglyceride levels. Novel therapies, including antisense oligonucleotides (ASOs) and small interfering RNA (siRNA), such as volanesorsen, olezarsen, and plozasiran, have shown promising results in recent trials. These therapies not only effectively lower plasma triglyceride levels but also significantly reduce the incidence of acute pancreatitis.

SUMMARY

SHTG is a high-burden metabolic disorder that is associated with a significantly increased incidence and severity of acute pancreatitis. Traditional lifestyle interventions and conventional therapies, including fibrates and n-3 fatty acids, often provide only modest reductions in triglycerides and fail to prevent sHTG-associated acute pancreatitis. The emergence of novel and targeted RNA-therapies represents a potential breakthrough in the management of sHTG and acute pancreatitis prevention.

Integrating genetics and lifestyles for precision nutrition in hypertriglyceridemia: A UK Biobank and KoGES analysis

BACKGROUND

Hypertriglyceridemia is an independent risk factor for cardiovascular disease.

OBJECTIVE

This study examined the polygenic variants associated with high serum triglyceride concentration (high-TG) and their interactions with lifestyle factors using data from the UK Biobank (n = 479,300) and the Korean Genome and Epidemiology Study (KoGES; n = 57,939).

METHODS

High-TG group was categorized based on over 200 mg/dL fasting serum TG concentrations (Caucasians, UK Biobank, n = 100,543; Koreans, KoGES, n = 7211). Polygenic risk scores (PRS) were calculated using risk alleles from genetic variants identified through a genome-wide association study (GWAS) and generalized multifactor dimensionality reduction (GMDR) analyses.

RESULTS

Koreans showed higher frequencies of risk alleles in GCKR, APOA5, SIK3, and APOE genes compared to Caucasians. After adjusting for covariates, a PRS including lipoprotein lipase (LPL)_rs328, apolipoprotein A5 (APOA5)_rs2072560, and glucokinase regulator (GCKR)_rs780093 showed a 2.2-fold (UK Biobank) and 2.6-fold (KoGES) increased risk of high-TG among Caucasians and Koreans, respectively. In both cohorts, the PRS was positively associated with metabolic syndrome, serum low high-density lipoprotein (HDL)-cholesterol, and high low-density lipoprotein (LDL)-cholesterol concentrations, but inversely associated with high-TG. These variants were linked to the chylomicron and very low-density lipoprotein (VLDL) remodeling pathways in Multimarker Analysis of GenoMic Annotation (MAGMA) gene analysis. Significant interactions were observed between the PRS and lifestyle factors, namely plant-based diet (P = .0008), alcohol consumption (P = .0022), and smoking status (P < .001) in both cohorts. Additionally, in the KoGES cohort, vitamin D intake (P = .027) and the glycemic index (P = .045) interacted with the PRS to influence high-TG risk.

CONCLUSION

Similar genetic variants affected high-TG risk across populations despite ethnic differences in risk allele frequencies. The identified PRS significantly interacted with plant-based diet, alcohol consumption, and smoking status in both cohorts, with additional interactions observed with vitamin D intake and glycemic index in the Korean cohort.

Familial Combined Hyperlipidemia: Myth or Reality?

PURPOSE OF REVIEW

Familial combined hyperlipidemia (FCHL) was first described by Goldstein and co-workers in 1973 as a multiple-type hyperlipidemia in pedigrees with premature myocardial infarction. However, it can be questioned what actually defines FCHL.

RECENT FINDINGS

Although initially regarded as an autosomal dominant disorder, quantitative trait linkage analyses have revealed multiple genes that are associated with the FCHL phenotype. With the advent of genome-wide association studies and next generation sequencing it has been confirmed that FCHL is a polygenic disorder and the associated gene variants, mostly with a triglyceride-raising effect, are not unique to FCHL. Furthermore, epidemiological studies have demonstrated that the multiple-type hyperlipidemia is also not specifically confined to FCHL. This review provides a historical overview of the metabolic and genetic abnormalities that characterize FCHL. Integration of these findings with recent population-based, genetic studies results in a new pathophysiological concept of FCHL. This model provides practical guidance on how to approach an individual patient with an 'FCHL phenotype'.

Genetic Variants in Severe Hypertriglyceridemia Among Taiwanese Participants - Insights From Genome-Wide Association and Whole-Exome Sequencing Analyses

BACKGROUND

There are limited data on the use of whole-exome sequencing (WES) to diagnose severe hypertriglyceridemia. Our aim was to identify candidate genes linked to triglyceride levels via a genome-wide association study (GWAS) and to recruit participants with severe hypertriglyceridemia for WES to assess allelic variants in the candidate genes.

METHODS AND RESULTS

A GWAS was conducted involving 120,140 participants to identify lead loci associated with blood triglyceride levels. Following the identification of these lead loci, WES was performed on DNA samples from 29 participants with hypertriglyceridemia whose triglyceride levels exceeded 800 mg/dL to assess variations in the corresponding genes. In the GWAS of 120,140 participants, the apolipoprotein A5 (APOA5) locus on chromosome 11 showed the strongest association with blood triglyceride levels (lead single nucleotide polymorphism [SNP] rs2075291; P=3.07×10-108), along with 5 independent SNPs (most significant P=7.84×10-167). Other key loci included BUD13 homolog (BUD13; P=2.73×10-62), glucokinase regulator (GCKR; P=2.63×10-24), and lipoprotein lipase (LPL; P=1.50×10-11). WES in 29 hypertriglyceridemia patients identified additional genes, including ALDH1A2, APOC1, LPL, RGS7, and SIK3, showing significant allele frequency variations and potential roles in lipid metabolism.

CONCLUSIONS

Our study confirms the role of known genetic loci in triglyceride metabolism and hypertriglyceridemia while uncovering novel loci, offering new perspectives on lipid regulation and potential avenues for therapeutic advancements.

The role of lipase maturation factor 1 in hypertriglyceridaemia and atherosclerosis: An update

Lipase maturation factor 1 is an endoplasmic reticulum-resident transmembrane protein, which acts as a critical chaperone necessary for the folding, dimerisation, and secretion of lipases. In this review, we summarise data about the recently revealed role of lipase maturation factor 1 in endoplasmic reticulum redox homeostasis, its novel interaction partners among oxidoreductases and lectin chaperones, and the identification of fibronectin and the low-density lipoprotein receptor as novel non-lipase client proteins of lipase maturation factor 1. Additionally, the role of lipase maturation factor 1-derived circular RNA in atherosclerosis progression via the miR-125a-3p/vascular endothelial growth factor A\Fibroblast Growth Factor 1 axis is discussed. Finally, we focus on the causative role of lipase maturation factor 1 variants in the development of hypertriglyceridaemia - a type of dyslipidaemia that significantly contributes to the development of atherosclerosis and other cardiovascular diseases via different mechanisms.

Efficacy and safety of omega-3-acid ethyl acetate 90 capsules in severe hypertriglyceridemia: A randomized, controlled, multicenter study

Omega-3-acid ethyl acetate 90 capsules (containing 465 mg of eicosapentaenoic acid and 375 mg docosahexaenoic acid) is composed of highly purified omega-3 polyunsaturated fatty acid (PUFA) ethyl esters, whose lipid-lowering effect for severe hypertriglyceridemia (HTG) treatment is unclear. This study aimed to evaluate the efficacy and safety of omega-3-acid ethyl acetate 90 capsules in patients with severe HTG. In this randomized, double-blind, placebo-controlled, multicenter study, 239 patients with severe HTG were enrolled and randomized (1:1) into omega-3 group (N = 122) and placebo group (N = 117) to receive 12-week corresponding treatments. Lipid-related indexes were obtained at treatment initiation (W0), 4 weeks (W4), W8, and W12 after treatment. Adverse events and adverse drug reactions were recorded. Triacylglycerols (TAG), total cholesterol (TC), non-high-density lipoprotein cholesterol (non-HDL-C), very-low-density lipoprotein cholesterol (VLDL-C), and apolipoprotein C-III (Apo C-III) at W4, W8, and W12 were decreased in the omega-3 group versus the placebo group (all p < 0.05). Moreover, the percentage changes of TAG, TC, non-HDL-C, and VLDL-C from W0 to W4, W8, and W12, and the percentage change of Apo C-III from W0 to W4 and W8, were more obvious in the omega-3 group compared with the placebo group (all p < 0.05). However, no difference was observed in the percentage changes of HDL-C, low-density lipoprotein cholesterol (LDL-C), and LDL-C/HDL-C ratio during follow-up between groups (all p > 0.05). Additionally, there was no discrepancy in adverse events and adverse drug reactions between groups (all p > 0.05). Omega-3-acid ethyl acetate 90 capsules exhibit satisfied lipid-lowering effect with tolerable safety profile in patients with severe HTG.

Necrotizing Pancreatitis Due to Very High Triglyceride Level: A Case Report

In the United States, acute pancreatitis is one of the most common gastrointestinal conditions that results in hospital admission. Necrotizing pancreatitis is a form of acute pancreatitis that can lead to various local and systemic complications. It is also associated with a high risk of mortality and morbidity without prompt intervention. In this case report, we discuss the case of a 33-year-old female with a history of alcoholism hospitalized with necrotizing pancreatitis due to hypertriglyceridemia. Our goal was to promptly identify the case by evaluating the signs and symptoms and intervening to prevent the associated complications. Our other objective was to change the diet and lifestyle of the patient to prevent the recurrence of necrotizing pancreatitis and readmission for the same reason.

Targeting Apolipoprotein C-III for the Management of Severe Hypertriglyceridemia: Current Research and Future Directions

Hypertriglyceridemia is characterized by elevated triglyceride levels in the blood, which increases the risk of cardiovascular disease and pancreatitis. This condition stems from multiple factors including lifestyle choices, genetics, and conditions such as diabetes and metabolic syndrome. Apolipoprotein C-III (APOC3), a protein for lipid metabolism, hinders enzymes necessary for breaking down triglycerides and thus plays a key role in hypertriglyceridemia. Variations in the APOC3 gene are associated with varying triglyceride levels among individuals. Recent genetic studies and clinical trials have shed light on the potential of targeting APOC3 as a potentially promising therapeutic modality of hypertriglyceridemia. Antisense oligonucleotides like volanesorsen have displayed effectiveness in lowering triglyceride levels in individuals with severe hypertriglyceridemia. This review article delves into how APOC3 influences triglyceride control and its potential use in targeting APOC3 to manage severe hypertriglyceridemia.

Hypertriglyceridemia: Molecular and Genetic Landscapes

Lipid disorders represent one of the most worrisome cardiovascular risk factors. The focus on the impact of lipids on cardiac and vascular health usually concerns low-density lipoprotein cholesterol, while the role of triglycerides (TGs) is given poor attention. The literature provides data on the impact of higher plasma concentrations in TGs on the cardiovascular system and, therefore, on the outcomes and comorbidities of patients. The risk for coronary heart diseases varies from 57 to 76% in patients with hypertriglyceridemia. Specifically, the higher the plasma concentrations in TGs, the higher the incidence and prevalence of death, myocardial infarction, and stroke. Nevertheless, the metabolism of TGs and the exact physiopathologic mechanisms which try to explain the relationship between TGs and cardiovascular outcomes are not completely understood. The aims of this narrative review were as follows: to provide a comprehensive evaluation of the metabolism of triglycerides and a possible suggestion for understanding the targets for counteracting hypertriglyceridemia; to describe the inner physiopathological background for the relationship between vascular and cardiac damages derived from higher plasma concentrations in TGs; and to outline the need for promoting further insights in therapies for reducing TGs plasma levels.

Relation among hypertriglyceridaemia, cardiometabolic disease, and hereditary factors-design and rationale of the Stockholm hyperTRIglyceridaemia REGister study

Aims

Hypertriglyceridaemia (hTG) is associated with atherosclerotic cardiovascular disease, pancreatitis, and non-alcoholic fatty liver disease (NAFLD) in large population-based studies. The understanding of the impact of hereditary hTG and cardiometabolic disease status on the development of hTG and its associated cardiometabolic outcomes is more limited. We aimed to establish a multigenerational cohort to enable studies of the relationship between hTG, cardiometabolic disease and hereditary factors.

Methods and results

The population-based observational Stockholm hyperTRIglyceridaemia REGister (STRIREG) study includes 1 460 184 index individuals who have measured plasma triglycerides in the clinical routine in Region Stockholm, Sweden, between 1 January 2000 and 31 December 2021. The laboratory measurements also included basic haematology, blood lipid panel, liver function tests, and HbA1c. Using the Swedish Multi-Generation register, 2 147 635 parents and siblings to the indexes were identified to form the complete study cohort. Laboratory data from participants were combined with data from several national registers that provided information on the cause of death, medical diagnoses, dispensed medicines, and socioeconomic factors including country of birth, education level, and marital status.

Conclusion

The multi-generational longitudinal STRIREG cohort provides a unique opportunity to investigate different aspects of hTG as well as heredity for other metabolic diseases. Important outcome measures include mortality, cardiovascular mortality, major cardiovascular events, development of incident diabetes, and NAFLD. The STRIREG study will provide a deeper understanding of the impact of hereditary factors and associated cardiometabolic complications.

Genetic risk score in patients with the APOE2/E2 genotype as a predictor of familial dysbetalipoproteinemia

BACKGROUND

Familial dysbetalipoproteinemia (FD) is an autosomal recessive (rarely dominant) inherited disorder that is almost exclusively associated with the apolipoprotein E gene (APOE) variability. Nonetheless, only a small proportion of APOE2/E2 subjects develop the phenotype for mixed dyslipidemia; the context of other trigger metabolic or genetic factors remains unknown.

METHODS

One hundred and one patients with FD and eighty controls (all APOE2/E2 homozygotes; rs429358) were screened for 18 single-nucleotide polymorphisms (SNPs) within the genes involved in triglyceride metabolism.

RESULTS

Two SNPs were significantly associated with the FD phenotype (rs439401 within APOE; P < 0.0005 and rs964184 within ZPR1/APOA5/A4/C3/A1 gene cluster; P < 0.0001). Unweighted genetic risk scores - from these two SNPs (GRS2), and, also, additional 13 SNPs with P-value below 0.9 (GRS15) - were created as an additional tool to improve the risk estimation of FD development in subjects with the APOE2/E2 genotype. Both GRS2 and GRS15 were significantly (P < 0.0001) increased in patients and both GRSs discriminated almost identically between the groups (P = 0.86). Subjects with an unweighted GRS2 of three or more had an almost four-fold higher risk of FD development than other individuals (odds ratio (OR) 3.58, 95% confidence interva (CI): 1.78-7.18, P < 0.0005).

CONCLUSIONS

We identified several SNPs that are individual additive factors influencing FD development. The use of unweighted GRS2 is a simple and clinically relevant tool that further improves the prediction of FD in APOE2/E2 homozygotes with corresponding biochemical characteristics.

The Intersection of Genetic Factors, Aberrant Nutrient Metabolism and Oxidative Stress in the Progression of Cardiometabolic Disease

Cardiometabolic disease (CMD), which encompasses metabolic-associated fatty liver disease (MAFLD), chronic kidney disease (CKD) and cardiovascular disease (CVD), has been increasing considerably in the past 50 years. CMD is a complex disease that can be influenced by genetics and environmental factors such as diet. With the increased reliance on processed foods containing saturated fats, fructose and cholesterol, a mechanistic understanding of how these molecules cause metabolic disease is required. A major pathway by which excessive nutrients contribute to CMD is through oxidative stress. In this review, we discuss how oxidative stress can drive CMD and the role of aberrant nutrient metabolism and genetic risk factors and how they potentially interact to promote progression of MAFLD, CVD and CKD. This review will focus on genetic mutations that are known to alter nutrient metabolism. We discuss the major genetic risk factors for MAFLD, which include Patatin-like phospholipase domain-containing protein 3 (PNPLA3), Membrane Bound O-Acyltransferase Domain Containing 7 (MBOAT7) and Transmembrane 6 Superfamily Member 2 (TM6SF2). In addition, mutations that prevent nutrient uptake cause hypercholesterolemia that contributes to CVD. We also discuss the mechanisms by which MAFLD, CKD and CVD are mutually associated with one another. In addition, some of the genetic risk factors which are associated with MAFLD and CVD are also associated with CKD, while some genetic risk factors seem to dissociate one disease from the other. Through a better understanding of the causative effect of genetic mutations in CMD and how aberrant nutrient metabolism intersects with our genetics, novel therapies and precision approaches can be developed for treating CMD.

Intracranial Aneurysms and Lipid Metabolism Disorders: From Molecular Mechanisms to Clinical Implications

Many vascular diseases are linked to lipid metabolism disorders, which cause lipid accumulation and peroxidation in the vascular wall. These processes lead to degenerative changes in the vessel, such as phenotypic transformation of smooth muscle cells and dysfunction and apoptosis of endothelial cells. In intracranial aneurysms, the coexistence of lipid plaques is often observed, indicating localized lipid metabolism disorders. These disorders may impair the function of the vascular wall or result from it. We summarize the literature on the relationship between lipid metabolism disorders and intracranial aneurysms below.

Comprehensive review on the pathogenesis of hypertriglyceridaemia-associated acute pancreatitis

It is well known, that the inflammatory process that characterizes acute pancreatitis (AP) can lead to both pancreatic damage and systemic inflammatory response syndrome (SIRS). During the last 20 years, there has been a growing incidence of episodes of acute pancreatitis associated with hypertriglyceridaemia (HTAP). This review provides an overview of triglyceride metabolism and the potential mechanisms that may contribute to developing or exacerbating HTAP. The article comprehensively discusses the various pathological roles of free fatty acid, inflammatory response mechanisms, the involvement of microcirculation, serum calcium overload, oxidative stress and the endoplasmic reticulum, genetic polymorphism, and gut microbiota, which are known to trigger or escalate this condition. Future perspectives on HTAP appear promising, with ongoing research focused on developing more specific and effective treatment strategies.

Current Data and New Insights into the Genetic Factors of Atherogenic Dyslipidemia Associated with Metabolic Syndrome

Atherogenic dyslipidemia plays a critical role in the development of metabolic syndrome (MetS), being one of its major components, along with central obesity, insulin resistance, and hypertension. In recent years, the development of molecular genetics techniques and extended analysis at the genome or exome level has led to important progress in the identification of genetic factors (heritability) involved in lipid metabolism disorders associated with MetS. In this review, we have proposed to present the current knowledge related to the genetic etiology of atherogenic dyslipidemia, but also possible challenges for future studies. Data from the literature provided by candidate gene-based association studies or extended studies, such as genome-wide association studies (GWAS) and whole exome sequencing (WES,) have revealed that atherogenic dyslipidemia presents a marked genetic heterogeneity (monogenic or complex, multifactorial). Despite sustained efforts, many of the genetic factors still remain unidentified (missing heritability). In the future, the identification of new genes and the molecular mechanisms by which they intervene in lipid disorders will allow the development of innovative therapies that act on specific targets. In addition, the use of polygenic risk scores (PRS) or specific biomarkers to identify individuals at increased risk of atherogenic dyslipidemia and/or other components of MetS will allow effective preventive measures and personalized therapy.

Gene transfer and genome editing for familial hypercholesterolemia

Familial hypercholesterolemia (FH) is an autosomal dominant inherited disease characterized by high circulating low-density lipoprotein (LDL) cholesterol. High circulating LDL cholesterol in FH is due to dysfunctional LDL receptors, and is mainly expressed by hepatocytes. Affected patients rapidly develop atherosclerosis, potentially leading to myocardial infarction and death within the third decade of life if left untreated. Here, we introduce the disease pathogenesis and available treatment options. We highlight different possible targets of therapeutic intervention. We then review different gene therapy strategies currently under development, which may become novel therapeutic options in the future, and discuss their advantages and disadvantages. Finally, we briefly outline the potential applications of some of these strategies for the more common acquired hypercholesterolemia disease.

Current and Emerging Therapies for Atherosclerotic Cardiovascular Disease Risk Reduction in Hypertriglyceridemia

Hypertriglyceridemia (HTG) is a prevalent medical condition in patients with cardiometabolic risk factors and is associated with an increased risk of atherosclerotic cardiovascular disease (ASCVD), if left undiagnosed and undertreated. Current guidelines identify HTG as a risk-enhancing factor and, as a result, recommend clinical evaluation and lifestyle-based interventions to address potential secondary causes of elevated triglyceride (TG) levels. For individuals with mild to moderate HTG at risk of ASCVD, statin therapy alone or in combination with other lipid-lowering medications known to decrease ASCVD risk are guideline-endorsed. In addition to lifestyle modifications, patients with severe HTG at risk of acute pancreatitis may benefit from fibrates, mixed formulation omega-3 fatty acids, and niacin; however, evidence does not support their use for ASCVD risk reduction in the contemporary statin era. Novel therapeutics including those that target apoC-III and ANGPTL3 have shown to be safe, well-tolerated, and effective for lowering TG levels. Given the growing burden of cardiometabolic disease and risk factors, public health and health policy strategies are urgently needed to enhance access to effective pharmacotherapies, affordable and nutritious food options, and timely health care services.

FABP4 Expression in Subcutaneous Adipose Tissue Is Independently Associated with Circulating Triglycerides in Obesity

Hypertriglyceridemia (HTG) has been associated with an increased risk of pancreatitis and cardiovascular disease. Adipose tissue plays a major role in lipid metabolism, mobilization and distribution. We have compared the histological and transcriptomic profiles of the subcutaneous (SAT) and visceral (VAT) adipose tissues from subjects with severe obesity undergoing bariatric surgery with (Ob-HTG, n = 37) and without HTG (Ob-NTG, n = 67). Mean age and BMI were 51.87 ± 11.21 years, 45.78 ± 6.96 kg/m² and 50.03 ± 10.17 years, 44.04 ± 4.69 kg/m², respectively. The Ob-HTG group showed higher levels of glycosylated hemoglobin, fasting plasma glucose, high-sensitivity C-reactive protein and prevalence of hypertension. The degree of fibrosis was increased by 14% in SAT from the Ob-HTG group (p = 0.028), while adipocyte size distribution was comparable. Twenty genes were found differentially expressed in SAT and VAT between study groups. Among them, only SAT expression of FABP4 resulted significantly associated with circulating triglyceride levels after adjusting for other covariates and independently explained 5% of the variance in triglyceride levels in the combined model. This relationship was not found in the cohort of lean or overweight patients with normotriglyceridemia (non-Ob, n = 21). These results emphasize the contribution of SAT to triglyceride concentrations in obesity and indicate that FABP4 may be a potential drug target for the treatment of HTG.

Genetic Testing for Hypertriglyceridemia in Academic Lipid Clinics: Implications for Precision Medicine-Brief Report

BACKGROUND

Severe hypertriglyceridemia is often caused by variants in genes of triglyceride metabolism. These variants include rare, heterozygous pathogenic variants (PVs), or multiple common, small-effect single nucleotide polymorphisms that can be quantified using a polygenic risk score (PRS). The role of genetic testing to examine PVs and PRS in predicting risk for pancreatitis and severity of hypertriglyceridemia is unknown.

METHODS

We examined the relationship of PVs and PRSs associated with hypertriglyceridemia with the highest recorded plasma triglyceride level and risk for acute pancreatitis in 363 patients from 3 academic lipid clinics who underwent genetic testing (GBinsight's Dyslipidemia Comprehensive Panel). Categories of hypertriglyceridemia included: normal triglyceride (<200 mg/dL), moderate (200-499 mg/dL), severe (500-999 mg/dL), or very severe (≥1000 mg/dL).

RESULTS

PVs and high PRSs were identified in 37 (10%) and 59 (16%) individuals, respectively. Patients with both had increased risk for very severe hypertriglyceridemia compared with those with neither genetic risk factor. Risk for acute pancreatitis was also increased in individuals with both genetic risk factors (odds ratio, 5.1 [P=0.02] after controlling for age, race, sex, body mass index, and highest triglyceride level), but not in individuals with PV or high PRS alone.

CONCLUSIONS

The presence of both PV and high PRS significantly increased risk for very severe hypertriglyceridemia and acute pancreatitis, whereas PV or PRS alone only modestly increased risk. Genetic testing may help identify patients with hypertriglyceridemia who have the greatest risk for developing pancreatitis and may derive the greatest benefit from novel triglyceride-lowering therapies.

Hypertriglyceridemia

Mild to moderate hypertriglyceridemia usually results from multiple small-effect variants in genes that control triglyceride metabolism. Hypertriglyceridemia is a critical component of the metabolic syndrome but can also occur secondary to several other conditions or drugs. Hypertriglyceridemia frequently is associated with an increased risk of cardiovascular disease (CVD). Statins are the mainstay of CVD prevention in hypertriglyceridemia, but eicosapentaenoic ethyl esters should be added in very-high-risk individuals. Although fibrates lower triglyceride levels, their role in CVD prevention remains unclear. Familial partial lipodystrophy is another relatively rare cause, although its true incidence is unknown.

A homozygous variant in the GPIHBP1 gene in a child with severe hypertriglyceridemia and a systematic literature review

Background: Due to nonspecific symptoms, rare dyslipidaemias are frequently misdiagnosed, overlooked, and undertreated, leading to increased risk for severe cardiovascular disease, pancreatitis and/or multiple organ failures before diagnosis. Better guidelines for the recognition and early diagnosis of rare dyslipidaemias are urgently required.

Methods: Genomic DNA was isolated from blood samples of a Pakistani paediatric patient with hypertriglyceridemia, and from his parents and siblings. Next-generation sequencing (NGS) was performed, and an expanded dyslipidaemia panel was employed for genetic analysis.

Results: The NGS revealed the presence of a homozygous missense pathogenic variant c.230G>A (NM_178172.6) in exon 3 of the GPIHBP1 (glycosylphosphatidylinositol-anchored high-density lipoprotein-binding protein 1) gene resulting in amino acid change p.Cys77Tyr (NP_835466.2). The patient was 5.5 years old at the time of genetic diagnosis. The maximal total cholesterol and triglyceride levels were measured at the age of 10 months (850.7 mg/dl, 22.0 mmol/L and 5,137 mg/dl, 58.0 mmol/L, respectively). The patient had cholesterol deposits at the hard palate, eruptive xanthomas, lethargy, poor appetite, and mild splenomegaly. Both parents and sister were heterozygous for the familial variant in the GPIHBP1 gene. Moreover, in the systematic review, we present 62 patients with pathogenic variants in the GPIHBP1 gene and clinical findings, associated with hyperlipoproteinemia.

Conclusion: In a child with severe hypertriglyceridemia, we identified a pathogenic variant in the GPIHBP1 gene causing hyperlipoproteinemia (type 1D). In cases of severe elevations of plasma cholesterol and/or triglycerides genetic testing for rare dyslipidaemias should be performed as soon as possible for optimal therapy and patient management.

Hypertriglyceridaemia in pregnancy: an unexpected diagnosis and its management

A woman in her 30s with gestational diabetes presented at 36 weeks’ gestation with reduced fetal movements and diminishing insulin requirements. In view of her gestation, she was induced and incidentally found to have profound hyponatraemia. Further biochemical investigations confirmed severe hypertriglyceridaemia and hypercholesterolaemia. This raises the possibility of secondary causes such as familial dysbetalipoproteinemia and polygenetic hypertriglyceridaemia. She was successfully managed by aggressive dietary modification. This involved a supervised fast followed by a fat-free diet. A fenofibrate was proposed but declined due to our patient’s wish to breastfeed. Management required considerable input from the multidisciplinary team. Treatment options to consider are aggressive dietary restriction of fat or the addition of a cholesterol-lowering medication, such as a fibrate. In refractory cases, a supervised fast may be required or, in cases where complications have arisen, apheresis. The patient and her baby made a good recovery with no long-lasting health implications.

Approach to patients with hypertriglyceridemia

Elevated triglyceride levels increase the risk of arteriosclerotic cardiovascular disease (ASCVD) and severely elevated triglyceride levels also increase the risk of triglyceride-induced pancreatitis. Although substantially reducing triglyceride levels will prevent pancreatitis, whether lowering triglycerides per se will reduce CVD risk is unclear. In this review, we outline several principles that will help in deciding who and how to treat patients with elevated triglyceride levels in order to prevent both ASCVD and pancreatitis. Using these principles will help in making decisions regarding the treatment of elevated triglyceride levels.

Familial combined hyperlipidemia is a polygenic trait

PURPOSE OF REVIEW

: Familial combined hyperlipidemia (FCH), defined by concurrently elevated plasma triglyceride (TG) and low-density lipoprotein (LDL) cholesterol, has long been investigated to characterize its genetic basis. Despite almost half a century of searching, a single gene cause for the phenotype has not yet been identified.

RECENT FINDINGS

: Recent studies using next-generation genetic analytic methods confirm that FCH has a polygenic basis, with a clear large contribution from the accumulation of small-to-moderate effect common single nucleotide polymorphisms (SNPs) throughout the genome that is associated with raising TG, and probably also those raising LDL cholesterol. On the other hand, rare monogenic variants, such as those causing familial hypercholesterolemia, play a negligible role, if any. Genetic profiling suggests that patients with FCH and hypertriglyceridemia share a strong polygenic basis and show a similar profile of multiple TG-raising common SNPs.

SUMMARY

: Recent progress in genomics has shown that most if not all of the genetic susceptibility to FCH is polygenic in nature. Future research should include larger cohort studies, with wider ancestral diversity, ancestry-specific polygenic scores, and investigation of epigenetic and lifestyle factors to help further elucidate the causative agents at play in cases where the genetic etiology remains to be defined.