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Talmud PJ, Futema M, Humphries SE. The genetic architecture of the familial hyperlipidaemia syndromes: rare mutations and common variants in multiple genes. Curr Opin Lipidol 2014; 25:274-81. [PMID: 24977977 DOI: 10.1097/mol.0000000000000090] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
PURPOSE OF REVIEW Genome-Wide Association Studies have provided robust identification of approximately 100 genetic loci determining plasma lipid parameters. Using these multiple common genetic lipid-determining variants in a 'gene score' has thrown new light on the mode of inheritance of familial lipid disorders. RECENT FINDINGS Different hypertriglyceridaemia states have been explained by the polygenic coinheritance of triglyceride-raising alleles. Taking this gene score approach with 12 LDL-cholesterol-raising alleles, we reported that for patients with a clinical diagnosis of familial hypercholesterolaemia, but no identified rare mutation in the familial hypercholesterolaemia-causing genes, LDL receptor, apolipoprotein B and PCSK9, the most likely explanation for their elevated LDL-C levels was a polygenic, not a monogenic, cause of the disease. SUMMARY These findings have wider implications for understanding complex disorders, and may very well explain the genetic basis of familial combined hyperlipidaemia, another familial lipid disorder in which the genetic cause(s) has remained elusive.
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Affiliation(s)
- Philippa J Talmud
- Centre for Cardiovascular Genetics, Institute of Cardiovascular Science, University College London, London, UK
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Mata P, Alonso R, Ruíz-Garcia A, Díaz-Díaz JL, González N, Gijón-Conde T, Martínez-Faedo C, Morón I, Arranz E, Aguado R, Argueso R, Perez de Isla L. [Familial combined hyperlipidemia: consensus document]. Aten Primaria 2014; 46:440-6. [PMID: 25034722 PMCID: PMC6985613 DOI: 10.1016/j.aprim.2014.04.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Revised: 04/02/2014] [Accepted: 04/22/2014] [Indexed: 01/14/2023] Open
Abstract
Familial combined hyperlipidemia (FCH) is a frequent disorder associated with premature coronary artery disease. It is transmitted in an autosomal dominant manner, although there is not a unique gene involved. The diagnosis is performed using clinical criteria, and variability in lipid phenotype and family history of hyperlipidemia are necessaries. Frequently, the disorder is associated with type2 diabetes mellitus, arterial hypertension and central obesity. Patients with FCH are considered as high cardiovascular risk and the lipid target is an LDL-cholesterol <100mg/dL, and <70mg/dL if cardiovascular disease or type 2 diabetes are present. Patients with FCH require lipid lowering treatment using potent statins and sometimes, combined lipid-lowering treatment. Identification and management of other cardiovascular risk factors as type 2 diabetes and hypertension are fundamental to reduce cardiovascular disease burden. This document gives recommendations for the diagnosis and global treatment of patients with FCH directed to specialists and general practitioners.
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Affiliation(s)
- Pedro Mata
- Fundación Hipercolesterolemia Familiar, Madrid, España.
| | - Rodrigo Alonso
- Clínica de Lípidos, Medicina Interna, IIS-Fundación Jiménez Díaz, Madrid, España
| | - Antonio Ruíz-Garcia
- Atención Primaria, Unidad de Lípidos y Prevención Cardiovascular, Centro de Salud, Pinto, Madrid, España
| | - Jose L Díaz-Díaz
- Clínica de Lípidos, Medicina Interna, Hospital Abente y Lago, A Coruña, España
| | - Noemí González
- Departamento de Endocrinología y Nutrición, Hospital Universitario La Paz, Madrid, España
| | - Teresa Gijón-Conde
- Centro de Salud Cerro del Aire, Majadahonda, Universidad Autónoma, Majadahonda, Madrid, España
| | | | | | | | - Rocío Aguado
- Departamento de Endocrinología, Hospital Universitario de León, León, España
| | - Rosa Argueso
- Departamento de Endocrinología, Hospital de Lugo, Lugo, España
| | - Leopoldo Perez de Isla
- Unidad de Imagen Cardiovascular, Servicio de Cardiología, Hospital Clínico San Carlos, Madrid, España
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Atherosclerosis progression in patients with autosomal dominant hypercholesterolemia in clinical practice. J Clin Lipidol 2014; 8:373-80. [DOI: 10.1016/j.jacl.2014.06.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2013] [Revised: 04/14/2014] [Accepted: 06/04/2014] [Indexed: 01/25/2023]
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Aguilar-Salinas CA, Tusie-Luna T, Pajukanta P. Genetic and environmental determinants of the susceptibility of Amerindian derived populations for having hypertriglyceridemia. Metabolism 2014; 63:887-94. [PMID: 24768220 PMCID: PMC4315146 DOI: 10.1016/j.metabol.2014.03.012] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2014] [Revised: 03/22/2014] [Accepted: 03/25/2014] [Indexed: 12/31/2022]
Abstract
Here, we discuss potential explanations for the higher prevalence of hypertriglyceridemia in populations with an Amerindian background. Although environmental factors are the triggers, the search for the ethnic related factors that explain the increased susceptibility of the Amerindians is a promising area for research. The study of the genetics of hypertriglyceridemia in Hispanic populations faces several challenges. Ethnicity could be a major confounding variable to prove genetic associations. Despite that, the study of hypertriglyceridemia in Hispanics has resulted in significant contributions. Two GWAS reports have exclusively included Mexican mestizos. Fifty percent of the associations reported in Caucasians could be generalized to the Mexicans, but in many cases the Mexican lead SNP was different than that reported in Europeans. Both reports included new associations with apo B or triglycerides concentrations. The frequency of susceptibility alleles in Mexicans is higher than that found in Europeans for several of the genes with the greatest effect on triglycerides levels. An example is the SNP rs964184 in APOA5. The same trend was observed for ANGPTL3 and TIMD4 variants. In summary, we postulate that the study of the genetic determinants of hypertriglyceridemia in Amerindian populations which have major changes in their lifestyle, may prove to be a great resource to identify new genes and pathways associated with hypertriglyceridemia.
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Affiliation(s)
- Carlos A Aguilar-Salinas
- Department of Endocrinology and Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición, México City, México.
| | - Teresa Tusie-Luna
- Unit of Molecular Biology and Genomic Medicine, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México and Instituto Nacional de Ciencias Médicas y Nutrición, México City, México.
| | - Päivi Pajukanta
- Department of Human Genetics, David Geffen School of Medicine at UCLA, Los Angeles, USA; Molecular Biology Institute at UCLA, Los Angeles, USA.
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New therapies targeting apoB metabolism for high-risk patients with inherited dyslipidaemias: what can the clinician expect? Cardiovasc Drugs Ther 2014; 27:559-67. [PMID: 23913122 DOI: 10.1007/s10557-013-6479-4] [Citation(s) in RCA: 127] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Apolipoprotein B (apoB) has a key role in the assembly and secretion of very low-density lipoprotein (VLDL) from the liver. Plasma apoB concentration affects the number of circulating atherogenic particles, and serves as an independent predictor of the risk of atherosclerotic cardiovascular disease. While statins are the most potent apoB-lowering agents currently prescribed, their efficacy in achieving therapeutic targets for low-density lipoprotein cholesterol (LDL-C) in high-risk patients, such as those with familial hypercholesterolaemia (FH), is limited. Resistance and intolerance to statins also occurs in a significant number of patients, necessitating new types of lipid-lowering therapies. Monoclonal antibodies against proprotein convertase subtilisin/kexin type 9 (PCSK9; AMG 145 and REGN727), a sequence-specific antisense oligonucleotide against apoB mRNA (mipomersen) and a synthetic inhibitor of microsomal triglyceride transfer protein (MTTP; lomitapide) have been tested in phase III clinical trials, particularly in patients with FH. The trials demonstrated the efficacy of these agents in lowering apoB, LDL-C, non-high-density lipoprotein cholesterol and lipoprotein(a) by 32-55 %, 37-66 %, 38-61 % and 22-50 % (AMG 145), 21-68 %, 29-72 %, 16-60 % and 8-36 % (REGN727), 16-71 %, 15-71 %, 12-66 % and 23-49 % (mipomersen) and 24-55 %, 25-51 %, 27-50 % and 15-19 % (lomitapide), respectively. Monoclonal antibodies against PCSK9 have an excellent safety profile and may be indicated not only in heterozygous FH, but also in statin-intolerant patients and those with other inherited dyslipidemias, such as familial combined hyperlipidaemia and familial elevation in Lp(a). Mipomersen and lomitapide increase hepatic fat content and are at present indicated for treating adult patients with homozygous FH alone.
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van Greevenbroek MMJ, Stalenhoef AFH, de Graaf J, Brouwers MCGJ. Familial combined hyperlipidemia: from molecular insights to tailored therapy. Curr Opin Lipidol 2014; 25:176-82. [PMID: 24811296 DOI: 10.1097/mol.0000000000000068] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE OF REVIEW This review presents recent basic and clinical developments in familial combined hyperlipidemia (FCHL). RECENT FINDINGS A variety of experiments have contributed to the elucidation of this complex disease. They consist of dynamic and gene expression studies in adipocytes, confirming the role of dysfunctional adipose tissue in the pathogenesis of FCHL and identifying potential new pathways, such as complement activation. Whole exome sequencing and classical linkage studies in FCHL pedigrees, some conducted with new traits (e.g. plasma proprotein convertase subtilisin/kexin type 9 [PCSK9] and phospholipid transfer protein activity), have revealed new genes of interest, among which SLC25A40 and LASS4. Finally, gene expression studies in liver biopsies and liver cell culture experiments have gained further insight in the role of upstream stimulatory factor 1, one of the most replicated genes in FCHL, in its pathogenesis.On the basis of these observations and recent phase II clinical trials, PCSK9 antagonizing is the most promising lipid-lowering therapy to be added to our current arsenal of statins and fibrates in FCHL treatment. SUMMARY Ongoing basic research provides a steady growth in our knowledge on the genes that are involved in FCHL as well as their metabolic function(s). This field of research may be enhanced when data are expanded and integrated for systems biology approaches. Our growing insights in the cause of FCHL allow for better, targeted treatment of dyslipidemia and prevention of cardiovascular complications.
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Affiliation(s)
- Marleen M J van Greevenbroek
- aDepartments of Internal Medicine and Endocrinology, Maastricht University Medical Centre bCARIM School for Cardiovascular Diseases/Laboratory for Metabolism and Vascular Medicine, Maastricht University, Maastricht cDivision of Vascular Medicine, Department of Internal Medicine, Radboud University Medical Centre, Nijmegen, The Netherlands
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Bile acid synthesis precursors in familial combined hyperlipidemia: The oxysterols 24S-hydroxycholesterol and 27-hydroxycholesterol. Biochem Biophys Res Commun 2014; 446:731-5. [DOI: 10.1016/j.bbrc.2013.12.131] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Accepted: 12/25/2013] [Indexed: 11/22/2022]
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Circulating PCSK9 is a strong determinant of plasma triacylglycerols and total cholesterol in homozygous carriers of apolipoprotein ε2. Clin Sci (Lond) 2014; 126:679-84. [DOI: 10.1042/cs20130556] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Plasma PCSK9, an important determinant of LDL-receptor degradation, is strongly related to total cholesterol and triacylglycerol levels in homozygous carriers of the apolipoprotein ε2 allele. This observation provides new insight into the pathogenesis of type III hyperlipidaemia and its treatment.
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Verkest KR. Is the metabolic syndrome a useful clinical concept in dogs? A review of the evidence. Vet J 2014; 199:24-30. [DOI: 10.1016/j.tvjl.2013.09.057] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2013] [Revised: 09/08/2013] [Accepted: 09/22/2013] [Indexed: 02/08/2023]
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Loria P, Marchesini G, Nascimbeni F, Ballestri S, Maurantonio M, Carubbi F, Ratziu V, Lonardo A. Cardiovascular risk, lipidemic phenotype and steatosis. A comparative analysis of cirrhotic and non-cirrhotic liver disease due to varying etiology. Atherosclerosis 2014; 232:99-109. [PMID: 24401223 DOI: 10.1016/j.atherosclerosis.2013.10.030] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Revised: 10/23/2013] [Accepted: 10/24/2013] [Indexed: 02/08/2023]
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APOE p.Leu167del mutation in familial hypercholesterolemia. Atherosclerosis 2013; 231:218-22. [DOI: 10.1016/j.atherosclerosis.2013.09.007] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Revised: 08/28/2013] [Accepted: 09/11/2013] [Indexed: 12/24/2022]
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Alves AC, Etxebarria A, Soutar AK, Martin C, Bourbon M. Novel functional APOB mutations outside LDL-binding region causing familial hypercholesterolaemia. Hum Mol Genet 2013; 23:1817-28. [DOI: 10.1093/hmg/ddt573] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
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Abstract
The three major pathways of lipoprotein metabolism provide a superb paradigm to delineate systematically the familial dyslipoproteinemias. Such understanding leads to improved diagnosis and treatment of patients. In the exogenous (intestinal) pathway, defects in LPL, apoC-II, APOA-V, and GPIHBP1 disrupt the catabolism of chylomicrons and hepatic uptake of their remnants, producing very high TG. In the endogenous (hepatic) pathway, six disorders affect the activity of the LDLR and markedly increase LDL. These include FH, FDB, ARH, PCSK9 gain-of-function mutations, sitosterolemia and loss of 7 alpha hydroxylase. Hepatic overproduction of VLDL occurs in FCHL, hyperapoB, LDL subclass pattern B, FDH and syndrome X, often due to insulin resistance and resulting in high TG, elevated small LDL particles and low HDL-C. Defects in APOB-100 and loss-of-function mutations in PCSK9 are associated with low LDL-C, decreased CVD and longevity. An absence of MTP leads to marked reduction in chylomicrons and VLDL, causing abetalipoproteinemia. In the reverse cholesterol pathway, deletions or nonsense mutations in apoA-I or ABCA1 transporter disrupt the formation of the nascent HDL particle. Mutations in LCAT disrupt esterification of cholesterol in nascent HDL by LCAT and apoA-1, and formation of spherical HDL. Mutations in either CETP or SR-B1 and familial high HDL lead to increased large HDL particles, the effect of which on CVD is not resolved. The major goal is to prevent or ameliorate the major complications of many familial dyslipoproteinemias, namely, premature CVD or pancreatitis. Dietary and drug treatment specific for each inherited disorder is reviewed.
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Affiliation(s)
- Peter O Kwiterovich
- Lipid Research Atherosclerosis Center, Helen Taussig Center, The Johns Hopkins University School of Medicine, David Rubenstein Building, Suite 3093, 200 N Wolfe St, Baltimore, MD 21287, USA.
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Brouwers MCGJ, Konrad RJ, van Himbergen TM, Isaacs A, Otokozawa S, Troutt JS, Schaefer EJ, van Greevenbroek MMJ, Stalenhoef AFH, de Graaf J. Plasma proprotein convertase subtilisin kexin type 9 levels are related to markers of cholesterol synthesis in familial combined hyperlipidemia. Nutr Metab Cardiovasc Dis 2013; 23:1115-1121. [PMID: 23333725 DOI: 10.1016/j.numecd.2012.11.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2012] [Revised: 10/13/2012] [Accepted: 11/24/2012] [Indexed: 02/05/2023]
Abstract
BACKGROUND AND AIMS Two recent independent studies showed that patients with familial combined hyperlipidemia (FCHL) have elevated plasma levels of proprotein convertase subtilisin kexin type 9 (PCSK9) and markers of cholesterol synthesis. Both PCSK9 expression and cholesterol synthesis are downstream effects of hepatic activation of sterol regulatory element binding protein 2 (SREBP2). The present study was conducted to study the relationship between plasma PCSK9 and markers of cholesterol synthesis in FCHL. METHODS AND RESULTS Markers of cholesterol synthesis (squalene, desmosterol, lathosterol), cholesterol absorption (campesterol, sitosterol, cholestanol) and PCSK9 were measured in plasma of FCHL patients (n = 103) and their normolipidemic relatives (NLR; n = 240). Plasma PCSK9, lathosterol and desmosterol levels were higher in FCHL patients than their NLR (p < 0.001, age and sex adjusted). Heritability calculations demonstrated that 35% of the variance in PCSK9 levels could be explained by additive genetic effects (p < 0.001). Significant age- and sex-adjusted correlations were observed for the relationship between PCSK9 and lathosterol, both unadjusted and adjusted for cholesterol, in the overall FCHL population (both p < 0.001). Multivariate regression analyses, with PCSK9 as the dependent variable, showed that the regression coefficient for FCHL status decreased by 25% (from 0.8 to 0.6) when lathosterol was included. Nevertheless, FCHL status remained an independent contributor to plasma PCSK9 (p < 0.001). CONCLUSIONS The present study confirms the previously reported high and heritable PCSK9 levels in FCHL patients. Furthermore, we now show that high PCSK9 levels are, in part, explained by plasma lathosterol, suggesting that SREBP2 activation partly accounts for elevated PCSK9 levels in FCHL.
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Affiliation(s)
- M C G J Brouwers
- Department of Internal Medicine, divisions of General Internal Medicine and Endocrinology, Cardiovascular Research Institute Maastricht, Maastricht University Medical Centre, PO Box 5800, 6202 AZ Maastricht, The Netherlands.
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Genetic influence in liver steatosis prevalence and proatherothrombotic/inflammatory profile in familial combined hyperlipoproteinemia. Int J Cardiol 2013; 168:536-9. [DOI: 10.1016/j.ijcard.2013.01.250] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Accepted: 01/13/2013] [Indexed: 12/29/2022]
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Brahm A, Hegele RA. Hypertriglyceridemia. Nutrients 2013; 5:981-1001. [PMID: 23525082 PMCID: PMC3705331 DOI: 10.3390/nu5030981] [Citation(s) in RCA: 92] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2013] [Revised: 03/14/2013] [Accepted: 03/15/2013] [Indexed: 12/20/2022] Open
Abstract
Hypertriglyceridemia (HTG) is commonly encountered in lipid and cardiology clinics. Severe HTG warrants treatment because of the associated increased risk of acute pancreatitis. However, the need to treat, and the correct treatment approach for patients with mild to moderate HTG are issues for ongoing evaluation. In the past, it was felt that triglyceride does not directly contribute to development of atherosclerotic plaques. However, this view is evolving, especially for triglyceride-related fractions and variables measured in the non-fasting state. Our understanding of the etiology, genetics and classification of HTG states is also evolving. Previously, HTG was considered to be a dominant disorder associated with variation within a single gene. The old nomenclature includes the term "familial" in the names of several hyperlipoproteinemia (HLP) phenotypes that included HTG as part of their profile, including combined hyperlipidemia (HLP type 2B), dysbetalipoproteinemia (HLP type 3), simple HTG (HLP type 4) and mixed hyperlipidemia (HLP type 5). This old thinking has given way to the idea that genetic susceptibility to HTG results from cumulative effects of multiple genetic variants acting in concert. HTG most is often a "polygenic" or "multigenic" trait. However, a few rare autosomal recessive forms of severe HTG have been defined. Treatment depends on the overall clinical context, including severity of HTG, concomitant presence of other lipid disturbances, and the patient's global risk of cardiovascular disease. Therapeutic strategies include dietary counselling, lifestyle management, control of secondary factors, use of omega-3 preparations and selective use of pharmaceutical agents.
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Affiliation(s)
- Amanda Brahm
- Department of Medicine, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada.
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