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Fularski P, Hajdys J, Majchrowicz G, Stabrawa M, Młynarska E, Rysz J, Franczyk B. Unveiling Familial Hypercholesterolemia-Review, Cardiovascular Complications, Lipid-Lowering Treatment and Its Efficacy. Int J Mol Sci 2024; 25:1637. [PMID: 38338916 PMCID: PMC10855128 DOI: 10.3390/ijms25031637] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2023] [Revised: 01/19/2024] [Accepted: 01/26/2024] [Indexed: 02/12/2024] Open
Abstract
Familial hypercholesterolemia (FH) is a genetic disorder primarily transmitted in an autosomal-dominant manner. We distinguish two main forms of FH, which differ in the severity of the disease, namely homozygous familial hypercholesterolemia (HoFH) and heterozygous familial hypercholesterolemia (HeFH). The characteristic feature of this disease is a high concentration of low-density lipoprotein cholesterol (LDL-C) in the blood. However, the level may significantly vary between the two mentioned types of FH, and it is decidedly higher in HoFH. A chronically elevated concentration of LDL-C in the plasma leads to the occurrence of certain abnormalities, such as xanthomas in the tendons and skin, as well as corneal arcus. Nevertheless, a significantly more severe phenomenon is leading to the premature onset of cardiovascular disease (CVD) and its clinical implications, such as cardiac events, stroke or vascular dementia, even at a relatively young age. Due to the danger posed by this medical condition, we have investigated how both non-pharmacological and selected pharmacological treatment impact the course of FH, thereby reducing or postponing the risk of clinical manifestations of CVD. The primary objective of this review is to provide a comprehensive summary of the current understanding of FH, the effectiveness of lipid-lowering therapy in FH and to explain the anatomopathological correlation between FH and premature CVD development, with its complications.
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Affiliation(s)
- Piotr Fularski
- Department of Nephrocardiology, Medical University of Lodz, ul. Zeromskiego 113, 90-549 Lodz, Poland
| | - Joanna Hajdys
- Department of Nephrocardiology, Medical University of Lodz, ul. Zeromskiego 113, 90-549 Lodz, Poland
| | - Gabriela Majchrowicz
- Department of Nephrocardiology, Medical University of Lodz, ul. Zeromskiego 113, 90-549 Lodz, Poland
| | - Magdalena Stabrawa
- Department of Nephrocardiology, Medical University of Lodz, ul. Zeromskiego 113, 90-549 Lodz, Poland
| | - Ewelina Młynarska
- Department of Nephrocardiology, Medical University of Lodz, ul. Zeromskiego 113, 90-549 Lodz, Poland
| | - Jacek Rysz
- Department of Nephrology, Hypertension and Family Medicine, Medical University of Lodz, ul. Zeromskiego 113, 90-549 Lodz, Poland
| | - Beata Franczyk
- Department of Nephrocardiology, Medical University of Lodz, ul. Zeromskiego 113, 90-549 Lodz, Poland
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Abstract
Atherosclerotic cardiovascular disease is the leading cause of death globally. Despite its important risk of premature atherosclerosis and cardiovascular disease, familial hypercholesterolemia (FH) is still largely underdiagnosed worldwide. It is one of the most frequently inherited diseases due to mutations, for autosomal dominant forms, in either of the LDLR, APOB, and PCSK9 genes or possibly a few mutations in the APOE gene and, for the rare autosomal forms, in the LDLRAP1 gene. The discovery of the genes implicated in the disease has largely helped to improve the diagnosis and treatment of FH from the LDLR by Brown and Goldstein, as well as the introduction of statins, to PCSK9 discovery in FH by Abifadel et al., and the very rapid availability of PCSK9 inhibitors. In the last two decades, major progress has been made in clinical and genetic diagnostic tools and the therapeutic arsenal against FH. Improving prevention, diagnosis, and treatment and making them more accessible to all patients will help reduce the lifelong burden of the disease.
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Affiliation(s)
- Marianne Abifadel
- UMR1148, Inserm, Hôpital Bichat-Claude Bernard, 46 rue Henri Huchard, F-75018 Paris, France.,Laboratory of Biochemistry and Molecular Therapeutics (LBTM), Faculty of Pharmacy, Pôle Technologie-Santé, Saint Joseph University of Beirut, Beirut, Lebanon
| | - Catherine Boileau
- UMR1148, Inserm, Hôpital Bichat-Claude Bernard, 46 rue Henri Huchard, F-75018 Paris, France.,Département de Génétique, AP-HP, Hôpital Bichat-Claude Bernard, Paris, France
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3
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Izar MCDO, Giraldez VZR, Bertolami A, Santos Filho RDD, Lottenberg AM, Assad MHV, Saraiva JFK, Chacra APM, Martinez TLR, Bahia LR, Fonseca FAH, Faludi AA, Sposito AC, Chagas ACP, Jannes CE, Amaral CK, Araújo DBD, Cintra DE, Coutinho EDR, Cesena F, Xavier HT, Mota ICP, Giuliano IDCB, Faria Neto JR, Kato JT, Bertolami MC, Miname MH, Castelo MHCG, Lavrador MSF, Machado RM, Souza PGD, Alves RJ, Machado VA, Salgado Filho W. Update of the Brazilian Guideline for Familial Hypercholesterolemia - 2021. Arq Bras Cardiol 2021; 117:782-844. [PMID: 34709306 PMCID: PMC8528358 DOI: 10.36660/abc.20210788] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Affiliation(s)
| | - Viviane Zorzanelli Rocha Giraldez
- Instituto do Coração (InCor) da Faculdade de Medicina da Universidade de São Paulo (FMUSP), São Paulo, SP - Brasil
- Grupo Fleury, São Paulo, SP - Brasil
| | | | | | - Ana Maria Lottenberg
- Hospital Israelita Albert Einstein (HIAE) - Faculdade Israelita de Ciências da Saúde Albert Einstein (FICSAE), São Paulo, SP - Brasil
- Faculdade de Medicina da Universidade de São Paulo, Laboratório de Lípides (LIM10), São Paulo, São Paulo, SP - Brasil
| | | | | | - Ana Paula M Chacra
- Instituto do Coração (InCor) da Faculdade de Medicina da Universidade de São Paulo (FMUSP), São Paulo, SP - Brasil
| | | | | | | | | | - Andrei C Sposito
- Universidade Estadual de Campinas (UNICAMP), Campinas, SP - Brasil
| | | | - Cinthia Elim Jannes
- Instituto do Coração (InCor) da Faculdade de Medicina da Universidade de São Paulo (FMUSP), São Paulo, SP - Brasil
| | | | | | | | | | - Fernando Cesena
- Hospital Israelita Albert Einstein (HIAE), São Paulo, SP - Brasil
| | | | | | | | | | | | | | - Marcio Hiroshi Miname
- Instituto do Coração (InCor) da Faculdade de Medicina da Universidade de São Paulo (FMUSP), São Paulo, SP - Brasil
| | - Maria Helane Costa Gurgel Castelo
- Universidade Federal do Ceará (UFC), Fortaleza, CE - Brasil
- Hospital do Coração de Messejana, Fortaleza, CE - Brasil
- Professora da Faculdade Unichristus, Fortaleza, CE - Brasil
| | - Maria Sílvia Ferrari Lavrador
- Hospital Israelita Albert Einstein (HIAE) - Faculdade Israelita de Ciências da Saúde Albert Einstein (FICSAE), São Paulo, SP - Brasil
| | - Roberta Marcondes Machado
- Faculdade de Medicina da Universidade de São Paulo, Laboratório de Lípides (LIM10), São Paulo, São Paulo, SP - Brasil
| | - Patrícia Guedes de Souza
- Hospital Universitário Professor Edgard Santos da Universidade Federal da Bahia (UFBA), Salvador, BA - Brasil
| | | | | | - Wilson Salgado Filho
- Instituto do Coração (InCor) da Faculdade de Medicina da Universidade de São Paulo (FMUSP), São Paulo, SP - Brasil
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4
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Moradi A, Maleki M, Ghaemmaghami Z, Khajali Z, Noohi F, Moghadam MH, Kalyinia S, Mowla SJ, Seidah NG, Malakootian M. Mutational Spectrum of LDLR and PCSK9 Genes Identified in Iranian Patients With Premature Coronary Artery Disease and Familial Hypercholesterolemia. Front Genet 2021; 12:625959. [PMID: 33732287 PMCID: PMC7959244 DOI: 10.3389/fgene.2021.625959] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Accepted: 01/11/2021] [Indexed: 12/12/2022] Open
Abstract
Familial hypercholesterolemia (FH) is a common, yet underdiagnosed, genetic disorder characterized by lifelong elevated low-density lipoprotein cholesterol levels, which can increase the risk of early-onset coronary artery disease (CAD). In the present study, we screened the nucleotide variations of the LDLR and PCSK9 genes, as well as a part of the APOB gene, in Iranian patients with FH and premature CAD to find the genetic cause of the disorder. Fifteen unrelated individuals with a clinical diagnosis of FH and premature CAD were recruited. Direct DNA sequencing was applied to screen the whole coding exons and exon-intron boundaries of the LDLR and PCSK9 genes and the main parts of their introns, together with exon 26 of the APOB gene. The pathogenicity of the identified mutations was investigated via either segregation analyses in the family or in silico predictive software. Six different point mutations (p.Cys148Tyr, p.Cys216Tyr, p.Cys302Trp, p.Cys338Trp, p.Leu479Gln, and p.G593Afs∗72) in LDLR and a double mutation (p.Asp172His and p.Ala53Val) in both LDLR and PCSK9 genes were identified in seven families with clinically diagnosed FH (43%), whereas no pathogenic mutations were found in eight families with clinically diagnosed FH. This study is the first to identify 1 pathogenic mutation in the LDLR gene (c.1014C > G [p.Cys338Trp]) and to cosegregate it from the affected individual in the family. No mutations were found in the APOB gene, whereas several silent mutations/polymorphisms were identified in the LDLR and PCSK9 genes. Genetic testing and reports on nucleotide alterations in the Iranian population are still limited. Our findings not only further confirm the significant role of FH in the incidence of premature CAD but also enlarge the spectrum of LDLR and PCSK9 variations and exhibit the heterogeneity of FH in Iranians. In patients with no mutation in the examined genes, the disease could be begotten either by a polygenic cause or by gene defects occurring in other related genes and regions not targeted in this study.
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Affiliation(s)
- Arman Moradi
- Department of Molecular Genetics, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran
| | - Majid Maleki
- Cardiogenetic Research Center, Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Zahra Ghaemmaghami
- Cardiogenetic Research Center, Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Zahra Khajali
- Cardiogenetic Research Center, Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Feridoun Noohi
- Cardiogenetic Research Center, Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Maryam Hosseini Moghadam
- Cardiogenetic Research Center, Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Samira Kalyinia
- Cardiogenetic Research Center, Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Seyed Javad Mowla
- Department of Molecular Genetics, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran
| | - Nabil G. Seidah
- Laboratory of Biochemical Neuroendocrinology, Montreal Clinical Research Institute, University of Montreal, Montreal, QC, Canada
| | - Mahshid Malakootian
- Cardiogenetic Research Center, Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, Iran
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Familial Hypercholesterolaemia in 2020: A Leading Tier 1 Genomic Application. Heart Lung Circ 2019; 29:619-633. [PMID: 31974028 DOI: 10.1016/j.hlc.2019.12.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2019] [Revised: 11/26/2019] [Accepted: 12/03/2019] [Indexed: 12/15/2022]
Abstract
Familial hypercholesterolaemia (FH) is caused by a major genetic defect in the low-density lipoprotein (LDL) clearance pathway. Characterised by LDL-cholesterol elevation from birth, FH confers a significant risk for premature coronary artery disease (CAD) if overlooked and untreated. With risk exposure beginning at birth, early detection and intervention is crucial for the prevention of CAD. Lowering LDL-cholesterol with lifestyle and statin therapy can reduce the risk of CAD. However, most individuals with FH will not reach guideline recommended LDL-cholesterol targets. FH has an estimated prevalence of approximately 1:250 in the community. Multiple strategies are required for screening, diagnosing and treating FH. Recent publications on FH provide new data for developing models of care, including new therapies. This review provides an overview of FH and outlines some recent advances in the care of FH for the prevention of CAD in affected families. The future care of FH in Australia should be developed within the context of the National Health Genomics Policy Framework.
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Porntadavity S, Jeenduang N. Structure–Function Relationships of LDL Receptor Missense Mutations Using Homology Modeling. Protein J 2019; 38:447-462. [DOI: 10.1007/s10930-019-09860-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Escate R, Padro T, Borrell-Pages M, Suades R, Aledo R, Mata P, Badimon L. Macrophages of genetically characterized familial hypercholesterolaemia patients show up-regulation of LDL-receptor-related proteins. J Cell Mol Med 2016; 21:487-499. [PMID: 27680891 PMCID: PMC5323824 DOI: 10.1111/jcmm.12993] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Accepted: 08/18/2016] [Indexed: 12/28/2022] Open
Abstract
Familial hypercholesterolaemia (FH) is a major risk for premature coronary heart disease due to severe long‐life exposure to high LDL levels. Accumulation of LDL in the vascular wall triggers atherosclerosis with activation of the innate immunity system. Here, we have investigated (i) gene expression of LDLR and LRPs in peripheral blood cells (PBLs) and in differentiated macrophages of young FH‐patients; and (ii) whether macrophage from FH patients have a differential response when exposed to high levels of atherogenic LDL. PBLs in young heterozygous genetically characterized FH patients have higher expression of LRP5 and LRP6 than age‐matched healthy controls or patients with secondary hypercholesterolaemia. LRP1 levels were similar among groups. In monocyte‐derived macrophages (MACs), LRP5 and LRP1 transcript levels did not differ between FHs and controls in resting conditions, but when exposed to agLDL, FH‐MAC showed a highly significant up‐regulation of LRP5, while LRP1 was unaffected. PBL and MAC cells from FH patients had significantly lower LDLR expression than control cells, independently of the lipid‐lowering therapy. Furthermore, exposure of FH‐MAC to agLDL resulted in a reduced expression of CD163, scavenger receptor with anti‐inflammatory and atheroprotective properties. In summary, our results show for first time that LRPs, active lipid‐internalizing receptors, are up‐regulated in innate immunity cells of young FH patients that have functional LDLR mutations. Additionally, their reduced CD163 expression indicates less atheroprotection. Both mechanisms may play a synergic effect on the onset of premature atherosclerosis in FH patients.
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Affiliation(s)
- Rafael Escate
- Cardiovascular Research Center (CSIC-ICCC), IIB-Sant Pau, Barcelona, Spain
| | - Teresa Padro
- Cardiovascular Research Center (CSIC-ICCC), IIB-Sant Pau, Barcelona, Spain
| | | | - Rosa Suades
- Cardiovascular Research Center (CSIC-ICCC), IIB-Sant Pau, Barcelona, Spain
| | - Rosa Aledo
- Cardiovascular Research Center (CSIC-ICCC), IIB-Sant Pau, Barcelona, Spain
| | | | - Lina Badimon
- Cardiovascular Research Center (CSIC-ICCC), IIB-Sant Pau, Barcelona, Spain.,Cardiovascular Research Chair, UAB, Barcelona, Spain
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Brautbar A, Leary E, Rasmussen K, Wilson DP, Steiner RD, Virani S. Genetics of familial hypercholesterolemia. Curr Atheroscler Rep 2015; 17:491. [PMID: 25712136 DOI: 10.1007/s11883-015-0491-z] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Familial hypercholesterolemia (FH) is a genetic disorder characterized by elevated low-density lipoprotein (LDL) cholesterol and premature cardiovascular disease, with a prevalence of approximately 1 in 200-500 for heterozygotes in North America and Europe. Monogenic FH is largely attributed to mutations in the LDLR, APOB, and PCSK9 genes. Differential diagnosis is critical to distinguish FH from conditions with phenotypically similar presentations to ensure appropriate therapeutic management and genetic counseling. Accurate diagnosis requires careful phenotyping based on clinical and biochemical presentation, validated by genetic testing. Recent investigations to discover additional genetic loci associated with extreme hypercholesterolemia using known FH families and population studies have met with limited success. Here, we provide a brief overview of the genetic determinants, differential diagnosis, genetic testing, and counseling of FH genetics.
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Affiliation(s)
- Ariel Brautbar
- Division of Genetics, Cook Children's Medical Center, Fort Worth, TX, USA,
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Huijgen R, Vissers MN, Defesche JC, Lansberg PJ, Kastelein JJP, Hutten BA. Familial hypercholesterolemia: current treatment and advances in management. Expert Rev Cardiovasc Ther 2014; 6:567-81. [PMID: 18402545 DOI: 10.1586/14779072.6.4.567] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Roeland Huijgen
- Academic Medical Center, Department of Vascular Medicine, Meibergreef 9 (Room F4-146), 1105 AZ, Amsterdam, The Netherlands.
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ten Kate GJR, Neefjes LA, Dedic A, Nieman K, Langendonk JG, Galema-Boers AJ, Roeters van Lennep J, Moelker A, Krestin GP, Sijbrands EJ, de Feyter PJ. The effect of LDLR-negative genotype on CT coronary atherosclerosis in asymptomatic statin treated patients with heterozygous familial hypercholesterolemia. Atherosclerosis 2013; 227:334-41. [DOI: 10.1016/j.atherosclerosis.2012.12.016] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Revised: 12/11/2012] [Accepted: 12/13/2012] [Indexed: 10/27/2022]
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Tichý L, Freiberger T, Zapletalová P, Soška V, Ravčuková B, Fajkusová L. The molecular basis of familial hypercholesterolemia in the Czech Republic: spectrum of LDLR mutations and genotype-phenotype correlations. Atherosclerosis 2012; 223:401-8. [PMID: 22698793 DOI: 10.1016/j.atherosclerosis.2012.05.014] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/28/2011] [Revised: 05/10/2012] [Accepted: 05/11/2012] [Indexed: 11/25/2022]
Abstract
BACKGROUND Familial hypercholesterolemia (FH), a major risk for coronary heart disease, is predominantly associated with mutations in the genes encoding the low-density lipoprotein receptor (LDLR) and its ligand apolipoprotein B (APOB). RESULTS In this study, we characterize the spectrum of mutations causing FH in 2239 Czech probands suspected to have FH. In this set, we found 265 patients (11.8%) with the APOB mutation p.(Arg3527Gln) and 535 patients (23.9%) with a LDLR mutation. In 535 probands carrying the LDLR mutation, 127 unique allelic variants were detected: 70.1% of these variants were DNA substitutions, 16.5% small DNA rearrangements, and 13.4% large DNA rearrangements. Fifty five variants were novel, not described in other FH populations. For lipid profile analyses, FH probands were divided into groups [patients with the LDLR mutation (LDLR+), with the APOB mutation (APOB+), and without a detected mutation (LDLR-/APOB-)], and each group into subgroups according to gender. The statistical analysis of lipid profiles was performed in 1722 probands adjusted for age in which biochemical data were obtained without FH treatment (480 LDLR+ patients, 222 APOB+ patients, and 1020 LDLR-/APOB- patients). Significant gradients in i) total cholesterol (LDLR+ patients > APOB+ patients = LDLR-/APOB- patients) ii) LDL cholesterol (LDLR+ patients > APOB+ patients = LDLR-/APOB- patients in men and LDLR+patients > APOB+ patients >LDLR-/APOB- patients in women), iii) triglycerides (LDLR-/APOB- patients > LDLR+ patients > APOB+ patients), and iv) HDL cholesterol (APOB+ patients > LDLR-/APOB- patients = LDLR+ patients) were shown. CONCLUSION Our study presents a large set of Czech patients with FH diagnosis in which DNA diagnostics was performed and which allowed statistical analysis of clinical and biochemical data.
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Affiliation(s)
- Lukáš Tichý
- Centre of Molecular Biology and Gene Therapy, University Hospital Brno, Brno, Czech Republic
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Chan DC, Watts GF. Postprandial lipoprotein metabolism in familial hypercholesterolemia: thinking outside the box. Metabolism 2012; 61:3-11. [PMID: 21945105 DOI: 10.1016/j.metabol.2011.07.014] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2011] [Revised: 07/14/2011] [Accepted: 07/26/2011] [Indexed: 10/17/2022]
Abstract
Familial hypercholesterolemia (FH) is a dominantly inherited disorder principally due to mutations in the low-density lipoprotein (LDL) receptor that classically cause markedly elevated plasma LDL cholesterol concentrations and premature coronary heart disease (CHD). However, elevated plasma LDL cholesterol alone does not fully account for the increase or variation in risk of CHD. We propose a hypothetical model for the role of postprandial dyslipoproteinemia based on the overproduction and decreased catabolism of triglyceride-rich lipoproteins, which may be a consequence of LDL receptor deficiency. Expression of postprandial dyslipoproteinemia in FH may also depend on the type of pathogenic gene variants and on coexistent conditions, particularly obesity and insulin resistance. Further research is required to investigate our model proposed and to test whether treating postprandial dyslipoproteinemia decreases CHD risk in FH incremental to standard therapy.
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Affiliation(s)
- Dick C Chan
- Metabolic Research Centre, School of Medicine and Pharmacology, University of Western Australia, Perth, Australia
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De Castro-Orós I, Pocoví M, Civeira F. The genetic basis of familial hypercholesterolemia: inheritance, linkage, and mutations. Appl Clin Genet 2010; 3:53-64. [PMID: 23776352 PMCID: PMC3681164 DOI: 10.2147/tacg.s8285] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Familial hypercholesterolemia (FH) is a genetic disorder of lipoprotein metabolism characterized by high plasma concentrations of low-density lipoprotein cholesterol (LDLc), tendon xanthomas, and increased risk of premature coronary heart disease. FH is one of the most common inherited disorders; there are 10,000,000 people with FH worldwide, mainly heterozygotes. The most common FH cause is mutations along the entire gene that encode for LDL receptor (LDLR) protein, but it has been also described that mutations in apolipoprotein B (APOB) and proprotein convertase subtilisin/kexin type 9 genes produce this phenotype. About 17%-33% of patients with a clinical diagnosis of monogenic hypercholesterolemia do not harbor any genetic cause in the known loci. Because FH has been considered as a public health problem, it is very important for an early diagnosis and treatment. Recent studies have demonstrated the influence of the LDLR mutation type in the FH phenotype, associating a more severe clinical phenotype and worse advanced carotid artherosclerosis in patients with null than those with receptor-defective mutations. Since 2004, a molecular FH diagnosis based on a genetic diagnostic platform (Lipochip(®); Progenika-Biopharma, Derio, Spain) has been developed. This analysis completes the adequate clinical diagnosis made by physicians. Our group has recently proposed new FH guidelines with the intention to facilitate the FH diagnosis. The treatment for this disease is based on the benefit of lowering LDLc and a healthy lifestyle. Actually, drug therapy is focused on using statins and combined therapy with ezetimibe and statins. This review highlights the recent progress made in genetics, diagnosis, and treatment for FH.
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Affiliation(s)
- Isabel De Castro-Orós
- Lipid Unit and Laboratorio de Investigación Molecular, Hospital Universitario Miguel Servet, Instituto Aragonés de Ciencias de la Salud (I+CS), Zaragoza, Spain
| | - Miguel Pocoví
- Departamento. Bioquímica y Biología Molecular y Celular. Universidad de Zaragoza, Instituto Aragonés de Ciencias de la Salud (I+CS), Zaragoza, Spain and Ciber de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, Spain
| | - Fernando Civeira
- Lipid Unit and Laboratorio de Investigación Molecular, Hospital Universitario Miguel Servet, Instituto Aragonés de Ciencias de la Salud (I+CS), Zaragoza, Spain
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Ejarque I, Real JT, Martinez-Hervas S, Chaves FJ, Blesa S, Garcia-Garcia AB, Millan E, Ascaso JF, Carmena R. Evaluation of clinical diagnosis criteria of familial ligand defective apoB 100 and lipoprotein phenotype comparison between LDL receptor gene mutations affecting ligand-binding domain and the R3500Q mutation of the apoB gene in patients from a South European population. Transl Res 2008; 151:162-7. [PMID: 18279815 DOI: 10.1016/j.trsl.2007.12.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2007] [Revised: 12/01/2007] [Accepted: 12/04/2007] [Indexed: 10/22/2022]
Abstract
Familial hypercholesterolemia (FH) and familial defective apoB 100 (FDB) are characterized by increased plasma low-density lipoprotein cholesterol (LDLc) levels and risk of coronary heart disease (CHD). FDB is clinically indistinguishable from FH. The aims of this study were to evaluate clinical diagnosis criteria for FDB and to compare the lipoprotein phenotype between carriers of LDL receptor (LDLR) gene mutations that affect the ligand-binding domain and subjects with the R3500Q mutation in apoB gene. We studied 213 subjects (113 probands) with FH and 19 heterozygous FDB subjects. Genetic diagnosis was determined by following a protocol based on Southern blot and polymerase chain reaction-single strand conformation polymorphism (SSCP) analysis. Thirty FH carriers of LDLR gene missense mutations that affect ligand-binding domain were matched by age, gender, and body mass index to the 19 FDB subjects (R3500Q mutation). Lipoprotein phenotype comparison was conducted between the 2 groups. FH patients showed plasma total and LDL cholesterol levels significantly higher than those in FDB patients. Three FDB showed plasma total and LDLc values in the normal range. Using the 1999 clinical Med-Ped criteria for diagnosis of genetic hypercholesterolemia, no FDB subjects had a confirmed diagnosis; it was probable in 36% of the subjects, it was possible in 32% of the subjects, and it could be excluded in the remaining 32% of the subjects. We conclude that the FDB lipoprotein phenotype was significantly less severe than that observed in FH carriers of LDLR gene missense ligand-binding domain mutations. Clinical Med-Ped diagnosis criteria tend to under-diagnose FDB.
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Affiliation(s)
- Ismael Ejarque
- Service of Endocrinology and Nutrition, Hospital Clinico Universitario, Department of Medicine, University of Valencia, Valencia, Spain
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15
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Humphries SE, Cranston T, Allen M, Middleton-Price H, Fernandez MC, Senior V, Hawe E, Iversen A, Wray R, Crook MA, Wierzbicki AS. Mutational analysis in UK patients with a clinical diagnosis of familial hypercholesterolaemia: relationship with plasma lipid traits, heart disease risk and utility in relative tracing. J Mol Med (Berl) 2005; 84:203-14. [PMID: 16389549 DOI: 10.1007/s00109-005-0019-z] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2005] [Accepted: 10/13/2005] [Indexed: 11/25/2022]
Abstract
As part of a randomised trial [Genetic Risk Assessment for Familial Hypercholesterolaemia (FH) Trial] of the psychological consequences of DNA-based and non-DNA-based diagnosis of FH, 338 probands with a clinical diagnosis of FH (46% with tendon xanthomas) were recruited. In the DNA-based testing arm (245 probands), using single-strand conformation polymorphism of all exons of the low-density lipoprotein receptor (LDLR) gene, 48 different pathogenic mutations were found in 62 probands (25%), while 7 (2.9%) of the patients had the R3500Q mutation in the apolipoprotein B (APOB) gene. Compared to those with no detected mutation, mean untreated cholesterol levels in those with the APOB mutation were similar, while in those with an LDLR mutation levels were significantly higher (None=9.15+/-1.62 vs LDLR=9.13+/-1.16 vs APOB=10.26+/-2.07 mmol/l p<0.001, respectively). Thirty seven percent of the detected mutations were in exon 3/4 of LDLR, and this group had significantly higher untreated cholesterol than those with other LDLR mutations (11.71+/-2.39 mmol/l vs 9.88+/-2.44 mmol/l, p=0.03), and more evidence of coronary disease compared to those with other LDLR or APOB mutations (36 vs 13% p=0.04). Of the probands with a detected mutation, 54 first-degree relatives were identified, of whom 27 (50%) had a mutation. Of these, 18 had untreated cholesterol above the 95th percentile for their age and gender, but there was overlap with levels in the non-carrier relatives such that 12% of subjects would have been incorrectly diagnosed on lipid levels alone. In the non-DNA-based testing arm (82 probands) only 19 of the 74 relatives identified had untreated cholesterol above the 95th percentile for their age and gender, which was significantly lower (p<0.0005) than the 50% expected for monogenic inheritance. These data confirm the genetic heterogeneity of LDLR mutations in the UK and the deleterious effect of mutations in exon 3 or 4 of LDLR on receptor function, lipids and severity of coronary heart disease. In patients with a clinical diagnosis of FH but no detectable mutation, there is weaker evidence for a monogenic cause compared with relatives of probands with LDLR mutations. This supports the usefulness of DNA testing to confirm diagnosis of FH for the treatment of hyperlipidaemia and for further cascade screening.
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Affiliation(s)
- Steve E Humphries
- Centre for Cardiovascular Genetics, British Heart Foundation Laboratories, Royal Free and University College London Medical School, Rayne Building, 5 University Street, London WC1E 6JJ, UK.
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16
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Koeijvoets KCMC, Wiegman A, Rodenburg J, Defesche JC, Kastelein JJP, Sijbrands EJG. Effect of low-density lipoprotein receptor mutation on lipoproteins and cardiovascular disease risk: a parent-offspring study. Atherosclerosis 2004; 180:93-9. [PMID: 15823280 DOI: 10.1016/j.atherosclerosis.2004.10.042] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2004] [Revised: 10/08/2004] [Accepted: 10/21/2004] [Indexed: 11/26/2022]
Abstract
Studies on the clinical consequences of different low-density lipoprotein (LDL) receptor genotypes in adult patients have yielded conflicting results. We hypothesized that children with familial hypercholesterolemia (FH) provide a better model to perform genotype-phenotype analyses than adults. We tested this hypothesis and assessed the effect of LDL receptor genotypes on lipoprotein levels and on parental risk of cardiovascular disease (CVD) in a pediatric FH cohort. We identified 75 different LDL receptor mutations in 645 children with heterozygous FH; in these children, null alleles were clearly associated with more elevated LDL cholesterol levels compared to receptor-defective mutations. Familial factors explained 50.4% of the variation in LDL cholesterol levels of this pediatric cohort compared to only 9.5% in adults. Parental CVD risk was not significantly different between carriers of null alleles and receptor-defective mutations (RR, 1.22; 95% CI, 0.76-1.95; p=0.4). The N543H/2393del9 mutation was associated with a less deteriorated lipid profile and the parents had less often CVD relative to parents with other mutations (RR, 0.39; 95% CI, 0.20-0.78; p=0.008). We could confirm that children with FH provide a better model to perform genotype-phenotype analyses. In particular, children with null alleles had significantly more elevated LDL cholesterol levels than carriers of other alleles but this was not associated with higher risk of CVD in the parents. Nonetheless, a specific LDL receptor mutation was associated with less deteriorated lipoprotein levels and a milder CVD risk.
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Affiliation(s)
- Kristel C M C Koeijvoets
- Department of Internal Medicine, Erasmus Medical Centre-D435, P.O. Box 2040, 3000 AC Rotterdam, The Netherlands
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Boswell EJ, Jeon H, Blacklow SC, Downing AK. Global defects in the expression and function of the low density lipoprotein receptor (LDLR) associated with two familial hypercholesterolemia mutations resulting in misfolding of the LDLR epidermal growth factor-AB pair. J Biol Chem 2004; 279:30611-21. [PMID: 15100232 DOI: 10.1074/jbc.m401412200] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The low density lipoprotein (LDL) receptor is a modular protein involved in the endocytosis of cholesterol-rich lipoproteins from the circulation. Mutations to the receptor result in familial hypercholesterolemia, and over 60 of these occur in the calcium-binding epidermal growth factor-like domain pair. Two selected mutations in this region (G322S and R329P) were introduced into the domain pair and analyzed by in vitro refolding. Both exhibited differing levels of protein misfolding with R329P being the most pronounced. Solution NMR studies of the mutant domain pairs after purification established that a fraction of protein maintains a native-like fold and that this fraction contains two intact calcium-binding sites. An in vivo analysis of intact receptors containing these binding sites showed significantly reduced cell-surface expression compared with the native LDL receptor levels, again with R329P showing the most severe decrease. The sum of these results suggests that either local changes in structure or domain misfolding may be associated with the mutations. There is also the possibility that the misfolding of the calcium-binding epidermal growth factor-like pair region is propagated to other regions of the intact receptor, resulting in more global defects. Surprisingly, for both mutants, those full-length receptors that fold and reach the cell surface retain the ability to bind LDL and release the ligand upon exposure to low pH. This analysis provides significant insight into the protein defect resulting from each of the two mutations and allows their classification to be 2B (partially transport-defective). The results also highlight a range of misfolding defects that may be associated with familial hypercholesterolemia and may enable the prediction of the consequences of homologous disease-causing mutations to other proteins.
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Affiliation(s)
- Emma J Boswell
- Department of Biochemistry, Division of Structural Biology, University of Oxford, South Parks Road, Oxford OX1 3QU, United Kingdom
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18
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Tremblay AJ, Lamarche B, Ruel IL, Hogue JC, Bergeron J, Gagné C, Couture P. Increased production of VLDL apoB-100 in subjects with familial hypercholesterolemia carrying the same null LDL receptor gene mutation. J Lipid Res 2004; 45:866-72. [PMID: 14967814 DOI: 10.1194/jlr.m300448-jlr200] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Early radiokinetic studies revealed that the classical metabolic defect in patients with familial hypercholesterolemia (FH) is hypocatabolism of LDL due to decreased LDL receptor activity. However, recent studies have suggested that hepatic oversecretion of apolipoprotein B-100 (apoB-100)-containing lipoproteins could also contribute to the markedly elevated plasma concentrations of LDL-cholesterol found in FH. The aim of this study was to examine the kinetics of apoB-100 labeled with a stable isotope (l-[5,5,5-D(3)] leucine) in five normolipidemic controls and in seven well-characterized FH subjects that included six FH heterozygotes and one FH homozygote carrying the same null LDL receptor gene mutation. As compared with controls, the VLDL apoB-100 production rate was increased by 50% in the FH heterozygotes and by 109% in the FH homozygote. Furthermore, FH subjects had significantly higher LDL apoB-100 pool size and lower LDL apoB-100 fractional catabolic rate than controls. These results indicate that the elevation of plasma LDL-cholesterol found in FH is attributable to both decreased clearance of LDL and increased hepatic production of apoB-100-containing lipoproteins.
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Abstract
Familial hypercholesterolemia (FH) is a clinical definition for a remarkable increase of cholesterol serum concentration, presence of xanthomas, and an autosomal dominant trait of either increased serum cholesterol or premature coronary artery disease (CAD). The identification of the low-density lipoprotein (LDL)-receptor (LDLR) as the underlying cause and its genetic characterization in FH patients revealed more insights in the trafficking of LDL, which primarily transports cholesterol to hepatic and peripheral cells. Mutations within LDLR result in hypercholesterolemia and, subsequently, cholesterol deposition in humans to a variable degree. This confirms the pathogenetic role of LDLR and also highlights the existence of additional factors in determining the phenotype. Autosomal dominant FH is caused by LDLR deficiency and defective apolipoprotein B-100 (APOB), respectively. Heterozygosity of the LDLR is relatively common (1:500). Clinical diagnosis is highly important and genetic diagnosis may be helpful, since treatment is usually effective for this otherwise fatal disease. Very recently, mutations in PCSK9 have been also shown to cause autosomal dominant hypercholesterolemia. For autosomal recessive hypercholesterolemia, mutations within the so-called ARH gene encoding a cellular adaptor protein required for LDL transport have been identified. These insights emphasize the crucial importance of LDL metabolism intra- and extracellularly in determining LDL-cholesterol serum concentration. Herein, we focus on the published European LDLR mutation data that reflect its heterogeneity and phenotypic penetrance.
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Affiliation(s)
- George V Z Dedoussis
- Department of Science Dietetics-Nutrition, Harokopio University of Athens, Athens, Greece
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20
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Real JT, Chaves FJ, Ejarque I, García-García AB, Valldecabres C, Ascaso JF, Armengod ME, Carmena R. Influence of LDL receptor gene mutations and the R3500Q mutation of the apoB gene on lipoprotein phenotype of familial hypercholesterolemic patients from a South European population. Eur J Hum Genet 2003; 11:959-65. [PMID: 14508510 DOI: 10.1038/sj.ejhg.5201079] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Few data are available on genotype-phenotype interactions among familial hypercholesterolemia (FH) patients in South European populations and there are no data about the influence of R3500Q mutation on lipoprotein phenotype compared to low-density lipoprotein receptor (LDLR) mutations. The objective of the study is to analyze the influence of mutations in the LDLR and apolipoprotein B (apoB) genes on lipoprotein phenotype among subjects clinically diagnosed of FH living in East Spain. In all, 113 FH index patients and 100 affected relatives were studied. Genetic diagnosis was carried out following a protocol based on Southern blot and PCR-SSCP analysis. A total of 118 FH subjects could be classified into three groups according to the type of LDLR mutations (null mutations, missense mutations affecting the ligand binding 3-5 repeat, and missense mutations outside this domain). In addition, the lipoprotein phenotype of these FH groups was compared with 19 heterozygous subjects with familial ligand-defective apoB (FDB), due to R3500Q mutation. FH patients carrying missense mutations affecting the ligand binding repeat 3-5 showed total and LDL cholesterol levels significantly higher than FH patients with missense mutations in other LDLR domains or FDB patients. FH subjects carrying null mutations showed lower high-density lipoprotein cholesterol plasma values compared to FH carrying missense mutations. FDB subjects showed the lowest total and LDL cholesterol plasma values. In conclusion, the type of LDLR gene mutation and R3500Q mutation influences the lipoprotein phenotype of FH population from East Spain.
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Affiliation(s)
- José T Real
- Service of Endocrinology and Nutrition, Department of Medicine, Hospital Clínico Universitario, University of Valencia, Spain
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Vergopoulos A, Knoblauch H, Schuster H. DNA testing for familial hypercholesterolemia: improving disease recognition and patient care. AMERICAN JOURNAL OF PHARMACOGENOMICS : GENOMICS-RELATED RESEARCH IN DRUG DEVELOPMENT AND CLINICAL PRACTICE 2003; 2:253-62. [PMID: 12421096 DOI: 10.2165/00129785-200202040-00005] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Cardiovascular disease is the leading cause of death worldwide and, like most chronic diseases, it has major genetic and environmental components. Among patients with coronary heart disease onset before the age of 55, about 5% of cases are attributable to heterozygous familial hypercholesterolemia (FH), a disease following autosomal dominant inheritance. About 50% of individuals with FH die before the age of 60 due to myocardial infarction. The frequency of FH is estimated to be 1 : 500. FH is related to mutations in the low-density lipoprotein (LDL)-cholesterol LDL-receptor gene and apolipoprotein B (apoB) gene. The identification of individuals with FH has been based on lipid levels and segregation of lipid levels within the family. However, phenotypes are overlapping and family history is not always informative. Therefore, a DNA-based genetic test for FH appears to offer the best alternative. The DNA test gives a simple yes/no answer. The FH test is a definitive tool for the identification of affected family members. The approach of targeted family genetic screening to find new patients is faster and more reliable compared with a biochemical form of screening. Early identification and efficient treatment of such patients is important and highly cost effective. There is evidence to suggest that the nature of the LDL-receptor (LDLR) mutation influences the degree of cholesterol lowering achieved by HMG-CoA reductase inhibitors (statins). The observed differences in the LDL-cholesterol (LDL-C) responses to these drugs among the various LDLR gene mutations are not yet completely understood. The relationships shown between LDLR mutation types and lipid levels, and the response of lipid levels to HMG-CoA reductase inhibitor treatment, will have to be investigated within the framework of pharmacogenetic studies. The variables, which are important in determining the overall atherosclerosis risk, are the result of combined activity in a dynamic network of numerous genes and environment. Candidate genes for atherosclerosis need to be further tested and validated. Future research should be directed at determining the significance of such targets, which patients with FH are at particularly high risk of premature cardiovascular disease, and which environmental factors are effective in modulating this risk. Genetics-based diagnostics will complement identification of FH while improving cardiovascular risk prediction, prevention of disease and treatment efficacy.
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Affiliation(s)
- Athanasios Vergopoulos
- Max Delbruck Center for Molecular Medicine, University Hospital Charité, Humboldt University of Berlin, Berlin, Germany
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22
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Lind S, Rystedt E, Eriksson M, Wiklund O, Angelin B, Eggertsen G. Genetic characterization of Swedish patients with familial hypercholesterolemia: a heterogeneous pattern of mutations in the LDL receptor gene. Atherosclerosis 2002; 163:399-407. [PMID: 12052488 DOI: 10.1016/s0021-9150(02)00038-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Familial hypercholesterolemia (FH) is an autosomal codominant disease, caused by mutations in the LDL receptor gene. To characterize the distribution of genetic aberrations in Swedish FH-patients fulfilling the clinical criteria of FH, we have investigated 150 unrelated Swedish patients for mutations in the LDL receptor gene and for the most common mutation causing familial ligand defective apo B-100 (FDB). Of the patients, 77 were recruited from Huddinge University Hospital in Stockholm and 73 from Sahlgren's University Hospital in Göteborg. Screening was carried out using SSCP and Southern blotting techniques, combined with DNA sequence analysis. In total, mutations regarded as cause for disease were identified in 55 patients (37%), representing 32 different types of mutations. In the LDL receptor gene we detected four nonsense mutations, 13 missense mutations, seven splice junction mutations, and four major rearrangements. In addition, two small deletions were identified and one base exchange in the promoter region. The most common mutation (apo B3500) causing FDB was found in three patients. The most frequent mutation was FH-Helsinki, reflecting the admixture of Finnish immigrants. We further identified 15 point mutations which were not considered to affect the function of the gene, and thus were regarded as polymorphic changes. This multitude of mutations reflects a heterogeneous genetic background in our series of Swedish FH-patients and differs from the situation in the other Scandinavian countries. Future studies should aim at characterizing the importance of other genes for the development of the FH phenotype.
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Affiliation(s)
- S Lind
- Department of Medical Laboratory Sciences and Technology, Centre for Inherited Metabolic Diseases, Karolinska Institute at Huddinge University Hospital, S-141 86 Stockholm, Sweden.
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23
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Dane-Stewart CA, Watts GF, Mamo JCL, Barrett PHR, Martins IJ, Dimmitt SB, Redgrave TG. Effect of Simvastatin on markers of triglyceride-rich lipoproteins in familial hypercholesterolaemia. Eur J Clin Invest 2002; 32:493-9. [PMID: 12153549 DOI: 10.1046/j.1365-2362.2002.01012.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND We have previously shown elevated fasting plasma concentrations of intestinal remnants, as reflected by apolipoprotein (apo) B-48 and remnant-like particle-cholesterol (RLP-C) in patients with heterozygous familial hypercholesterolaemia (FH). We now investigate the effect of an HMG-CoA reductase inhibitor (simvastatin) on chylomicron remnant metabolism using the measurement of fasting apoB-48 and RLP-C in FH patients after long- and short-term simvastatin therapy and after a wash-out period. We also piloted the response of a breath test, involving the measurement of the fractional catabolic rate (FCR) of an intravenously injected chylomicron remnant-like emulsion labeled with cholesteryl (13)C-oleate. METHODS Fifteen FH patients were studied after > 6 months 40 mg day(-1) simvastatin treatment (long-term), a wash-out period (4 weeks), and 4 weeks of simvastatin treatment (short-term). Apolipoprotein B-48 was determined by SDS-PAGE and Western blotting/enhanced chemiluminescence and RLP-C by an immunoseparation assay. The FCR of the chylomicron remnant-like emulsion was determined from the appearance of (13)CO(2) in the breath and by multicompartmental mathematical modelling. RESULTS Both long- and short-term treatment with simvastatin were associated with decreases in the plasma concentration of apoB-48 (P < 0.05) and RLP-C (P < 0.001), but there was no significant change in the FCR of the emulsion. CONCLUSIONS We suggest that long- and short-term treatments with simvastatin have comparable effects in decreasing the plasma concentration of triglyceride-rich remnants in heterozygous FH, as measured by fasting apoB-48 and RLP-C. The mechanisms for this may involve decreased production of hepatic and possibly intestinal lipoproteins, and/or up-regulation of hepatic receptor clearance pathways, but these changes are apparently not associated with a change in remnant clearance as measured kinetically by the (13)CO(2) breath test.
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24
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Real JT, Ascaso JF, Chaves FJ, González C, Puig O, Armengod ME, Carmena R. [Influence of plasma lipids, APOE genotype and type of LDL receptor gene mutations on myocardial infarction in subjects with familial hypercholesterolemia]. Med Clin (Barc) 2002; 118:681-5. [PMID: 12042130 DOI: 10.1016/s0025-7753(02)72496-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
BACKGROUND Our goal was to analyze the relationship of lipids and lipoproteins, APOE genotype and mutations of the LDL receptor gene with the prevalence of myocardial infarction (MI) in patients with familial hypercholesterolemia (FH) from a Southern European FH population. PATIENTS AND METHOD We studied 108 heterozygous FH subjects aged > 35 years (41 males). It was a cross-sectional study comparing individuals with FH and MI with individuals with FH without MI. In 88 FH subjects, a mutation of the LDL receptor gene was detected. These FH subjects were divided in carriers of null mutation or no null mutations. We compared lipids and lipoproteins and prevalences of LDL receptor type mutation and APOE genotype. RESULTS Parameters associated with MI were: age, presence of xanthomas and arcus cornealis, plasma concentrations of total cholesterol (TC), LDLc, TC/HDLc ratio > 5.3 and *4 genotype of the APOE gene. Odds ratio for MI were as follows: presence of xanthomas and arcus cornealis, 1.36 (CI 95%, 1.08-1.71; P = 0.01), age > 54 years (50 th of FH group), 1.56 (CI 95%, 1.19-2.04; P = 0.001) and plasma TC values > 332 mg/dl (50 th of FH group), 1.34 (CI 95%, 1.05-1.71; P = 0.019). In the logistic regression model, only age and TC were significantly associated with MI. CONCLUSIONS In FH subjects aged over 35 years from a Southern European population, MI is associated with age, plasma TC and LDLc values, TC/HDLc ratio and the *4 genotype. In addition, MI is related with age and TC plasma levels on an independent basis.
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Affiliation(s)
- José T Real
- Servicio de Endocrinología y Nutrición, Hospital Clínico Universitario, Departamento de Medicina, Universidad de Valencia, Spain
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25
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Barrett PHR, Watts GF. Shifting the LDL-receptor paradigm in familial hypercholesterolemia: novel insights from recent kinetic studies of apolipoprotein B-100 metabolism. ATHEROSCLEROSIS SUPP 2002; 2:1-4. [PMID: 11923121 DOI: 10.1016/s1567-5688(01)00012-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
Familial hypercholesterolemia (FH) is a dominantly inherited disorder associated with elevated plasma cholesterol concentrations and premature cardiovascular disease. In addition to impaired low density lipoprotein (LDL) receptor-mediated clearance of low density lipoproteins in FH, evidence from in vitro and in vivo studies suggests that hepatic oversecretion of apoB may contribute to the hypercholesterolemia. The proposed association between apoB secretion and FH may, however, be a function of the class of LDL receptor defect. Hepatic cholesterol pools appear to regulate apoB secretion and LDL receptor activity. Therefore, therapeutic regulation of cholesterogenesis in FH may have the dual effect of reducing hepatic apoB secretion and upregulating the LDL receptor. These effects may also be genetically determined.
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Affiliation(s)
- P Hugh R Barrett
- Department of Medicine, West Australian Heart Research Institute, Royal Perth Hospital, University of Western Australia, GPO Box X2213, Perth, WA 6847, Australia.
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Chaves FJ, Real JT, García-García AB, Civera M, Armengod ME, Ascaso JF, Carmena R. Genetic diagnosis of familial hypercholesterolemia in a South European outbreed population: influence of low-density lipoprotein (LDL) receptor gene mutations on treatment response to simvastatin in total, LDL, and high-density lipoprotein cholesterol. J Clin Endocrinol Metab 2001; 86:4926-32. [PMID: 11600564 DOI: 10.1210/jcem.86.10.7899] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The aims of this study were to examine the presence of mutations in the low-density lipoprotein receptor gene among subjects clinically diagnosed with familial hypercholesterolemia and to analyze whether the molecular diagnosis helps to predict the response to simvastatin treatment in our familial hypercholesterolemia population. Fifty-five probands and 128 related subjects with familial hypercholesterolemia were studied. Genetic diagnosis was carried out following a three-step protocol based on Southern blot and PCR-single strand conformational polymorphism analysis. A randomized clinical trial with simvastatin was conducted in 42 genetically diagnosed subjects with familial hypercholesterolemia classified as carriers of null mutations (n = 22) and of defective mutations (n = 20). A mutation-causing familial hypercholesterolemia was identified in 46 probands (84%). In 41 of them (89%), a total of 28 point mutations were detected, 13 of which have not been previously described. The remaining five probands (11%) were carriers of large rearrangements. Familial hypercholesterolemia with null mutations showed a poor response to simvastatin treatment. The mean percentage reduction of plasma total and low-density lipoprotein cholesterol levels in these subjects were significantly lower (24.8 +/- 10.3 vs. 34.8 +/- 10.9, P = 0.04 and 30.0 +/- 39.8 vs. 46.1 +/- 18.2, P = 0.02, respectively) than in subjects with defective mutations. Baseline and posttreatment high-density lipoprotein cholesterol plasma values were significantly lower in subjects with familial hypercholesterolemia with null mutations (P < 0.001). In an outbreed Caucasian population, a three-step protocol for genetic screening detected a mutation in the low-density lipoprotein receptor gene in a high percentage (84%) of subjects with familial hypercholesterolemia. Subjects with familial hypercholesterolemia with null mutations (class I) showed lower plasma high-density lipoprotein cholesterol values and a poor low-density lipoprotein cholesterol response to simvastatin treatment.
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Affiliation(s)
- F J Chaves
- Institute of Cytological Research, Service of Endocrinology and Nutrition, Hospital Clínico Universitario, University of Valencia, Avda. Blasco Ibáñez 17, E-46010 Valencia, Spain
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27
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Rukavina AS, Topić RZ, Ferencak G, Sucic M. A novel missense mutation C127R (FH Zagreb) in the LDL-receptor gene. Clin Chem Lab Med 2001; 39:505-8. [PMID: 11506462 DOI: 10.1515/cclm.2001.084] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
We employed the analysis of single-strand conformation polymorphisms to identify mutations in exon 4 of the low density lipoprotein receptor gene causing familial hypercholesterolemia. Three familial hypercholesterolemia heterozygotes had abnormal single-strand conformation polymorphism patterns. DNA sequencing revealed that the abnormal pattern of exon 4A was due to heterozygosity (T/C) at nucleotide 442. Nucleotide 442 is the first base of codon 127, and the T-->C mutation (C127R) changes this codon from CysTGT to ArgCGT. Abnormal patterns of exon 4B were due to heterozygosity (A/G) at nucleotide 662: nucleotide 662 is the second base of codon 200, and the A-->G mutation (D200G) changes this codon from AspGAC to GlyGGC. Mutation D200G was previously described as FH Padova, but mutation C127R (FH Zagreb) has not been reported previously. This novel mutation was confirmed by restriction endonuclease analysis with Dsa I. The screening of 420 familial hypercholesterolemia heterozygotes suggests that C127R and D200G account for about 0.7% of mutations causing familial hypercholesterolemia in Croatia.
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Affiliation(s)
- A S Rukavina
- Clinical Institute of Laboratory Diagnosis, Zagreb University School of Medicine and Clinical Hospital Center, Croatia.
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Chaves FJ, Real JT, García-García AB, Puig O, Ordovas JM, Ascaso JF, Carmena R, Armengod ME. Large rearrangements of the LDL receptor gene and lipid profile in a FH Spanish population. Eur J Clin Invest 2001; 31:309-17. [PMID: 11298777 DOI: 10.1046/j.1365-2362.2001.00823.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Familial hypercholesterolemia (FH) is an autosomal dominant disease caused by mutations in the low-density lipoprotein receptor (LDLR) gene. To date, there has not been a systematic survey of the frequency of gross mutations in the LDLR gene in the Spanish population. The objective of our study was to investigate large rearrangements in the Spanish FH population and the relation between the kind of large rearrangement and the phenotype in carrier families. MATERIALS AND METHODS The LDLR gene was screened to detect major rearrangements in a sample of 89 probands. Southern blot, long polymerase chain reaction (PCR), reverse transcription (RT) -PCR and DNA sequencing were used to detect and characterize the mutations. RESULTS Five large rearrangements were found in six probands. Two mutations were due to duplications of internal regions of the gene, whereas the rest were caused by partial deletions, which eliminated the promoter region in two cases. The internal rearrangements, two duplications and one deletion, were apparently caused by recombination between ALU sequences and the study of their mRNA indicated that the reading frame was maintained. The analysis of the lipid profile between patients with similar characteristics (age, sex, body mass index, etc.) but carrying mutations that either eliminated the promoter region or produced internal rearrangements showed significant differences (total cholesterol: 366.6 +/- 81.8 vs. 304.6 +/- 25.1 P = 0.023, and LDL cholesterol: 317.7 +/- 65.1 vs. 249.2 +/- 27.4 P = 0.003). CONCLUSIONS The frequency of large mutations in a Spanish FH sample was close to 7% and at least four of the mutations found had not been described in other populations. Mutations that eliminate the promoter region originate more severe hypercholesterolemia than defective mutations, which suggests that the absence of the promoter region and transcription of the LDLR gene is worse compensated than the synthesis of a defective LDL receptor.
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Affiliation(s)
- F J Chaves
- Fundación Valenciana de Investigaciones Biomédicas, Valencia, Spain
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Slimane MN, Lestavel S, Sun X, Maatouk F, Soutar AK, Ben Farhat MH, Clavey V, Benlian P, Hammami M. Fh-Souassi: a founder frameshift mutation in exon 10 of the LDL-receptor gene, associated with a mild phenotype in Tunisian families. Atherosclerosis 2001; 154:557-65. [PMID: 11257256 DOI: 10.1016/s0021-9150(00)00572-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Familial hypercholesterolemia (FH) has a higher prevalence in central Tunisia together with a milder clinical expression than in western countries. The molecular basis of FH in Tunisia remains unknown. Our aim was to identify FH-causing mutations in three unrelated families (21 subjects) from the area of Souassi (central Tunisia). In probands with a presentation of homozygous FH, the promoter and 18 exons of the low density lipoprotein (LDL)-receptor gene were sequenced in both orientations. A novel complex frameshift mutation was identified in exon 10, nucleotides 1477-1479 (TCT) at Serine 472 were replaced by an insertion of seven nucleotides (AGAGACA), producing a premature termination codon 43 amino acids downstream. Binding of 125I-labelled LDL at 4 degrees C to cultured fibroblasts from two probands showed <2% normal LDL-receptor activity. AvaII digestion of PCR amplified genomic DNA identified this unique mutation in all families; homozygotes n=11, heterozygotes n=10. All mutation carriers shared the same haplotype (7 RFLPs), suggesting that they had a common ancestor. Despite high plasma LDL levels (m=16.0+/-3.0 mmol/l) and extravascular cholesterol deposits, most homozygotes were diagnosed after puberty and had a delayed onset of cardiovascular complications. Moreover, most heterozygotes were free of clinical signs and had plasma LDL cholesterol in the normal range (4.7+/-1.3 mmol/l) without taking any lipid-lowering medication. This mild clinical phenotype which contrasted with the severity of the mutation, could not be explained by specific apolipoprotein E or lipoprotein lipase alleles.
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Affiliation(s)
- M N Slimane
- Laboratoire de Biochimie, Faculté de Médecine de Monastir, 5019, Monastir, Tunisia.
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30
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Dane-Stewart CA, Watts GF, Mamo JC, Dimmitt SB, Barrett PH, Redgrave TG. Elevated apolipoprotein B-48 and remnant-like particle-cholesterol in heterozygous familial hypercholesterolaemia. Eur J Clin Invest 2001; 31:113-7. [PMID: 11168448 DOI: 10.1046/j.1365-2362.2001.00785.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Apolipoprotein B-48 (apoB-48) is a marker of triglyceride-rich lipoprotein (TRL) remnants of intestinal origin. Chylomicron remnants are causally related to atherosclerosis. We have shown previously that fasting plasma apoB-48 may predict postprandial lipaemia. Remnant-like particle-cholesterol (RLP-C) may also reflect TRL remnants. We aimed to determine whether subjects with heterozygous familial hypercholesterolaemia (FH) had an accumulation of remnants of intestinal origin, as reflected by fasting plasma apoB-48 and RLP-C levels. The fasting plasma concentrations of apoB-48 and RLP-C were measured in 15 subjects with heterozygous FH and 15 age- and sex-matched, normolipidaemic subjects. ApoB-48 was determined using SDS-PAGE and a western blotting/enhanced chemi-luminescence technique. RLP-C was measured using an immuno-separation assay. Serum apolipoprotein B-100 (apoB-100) levels were measured using immunonephelometry; lipids were assayed enzymatically. Compared with controls, FH subjects had significantly elevated plasma concentrations of apoB-48 (29.3 median, 16.7-45.1 mg L-1 range vs. 12.8, 7.3-28.6; P < 0.001) and RLP-C (16.2, 1.5-114.3 mg dL-1 vs. 8.5, 5.0-13.5; P = 0.003), as well as serum total apoB-100 (1.9, 1.3-2.6 g L-1 vs. 1.0, 0.3-1.3; P < 0.001), LDL-cholesterol (8.1, 4.6-10.4 mmol L-1 vs. 3.5, 2.4-4.4; P < 0.001) and triglyceride (1.5, 0.6-5.6 mmol L-1 vs. 1.0, 0.4-1.8; P = 0.018). There was no significant difference in HDL cholesterol. The findings suggest that patients with heterozygous FH have elevated plasma concentrations of TRL remnants, including those of intestinal origin. This may be a consequence of decreased clearance of these particles by the LDL-receptor.
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31
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Real JT, Chaves FJ, Civera M, García-García AB, Ascaso JF, Armengod ME, Carmena R. [Influence of FH Valencia 1 and 2 mutations of the LDL receptor gene on the response to simvastatin in subjects with molecularly defined heterozygous familial hypercholesterolemia in Spain]. Med Clin (Barc) 2001; 116:81-5. [PMID: 11181283 DOI: 10.1016/s0025-7753(01)71731-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
BACKGROUND To analyse whether the molecular diagnosis in FH patients is useful to predict the response to treatment with simvastatin in a south European population. SUBJECTS AND METHOD A randomised clinical trial with no control group, with 20 mg/day of simvastatin was conducted in 27 genetically diagnosed FH subjects (11 male) from 8 FH families, randomly selected from 30 FH families with a molecular diagnosis. Clinical features and lipid parameters at baseline and after simvastatin treatment were compared between subjects classified as null mutations (FH Valencia 1 and 2; n = 11) and defective mutations (n = 16). RESULTS FH with null mutations (FH Valencia 1 and 2) have a poor response to simvastatin treatment. The mean reduction of plasma LDLc levels in subjects with null mutations were significantly lower (32.6% [9.5] vs 42.8% [12.2]; p = 0.03) than in subjects with defective mutations. Baseline and after treatment plasma HDLc values were also significantly lower in FH group with null mutations. No statistically significant differences were found at baseline, after treatment and in the response to treatment between males and females. CONCLUSIONS FH subjects with null alleles (FH Valencia 1 and 2) showed a poor response to simvastatin treatment. The type of LDL receptor gene mutation could predict the response to simvastatin in our south European FH population.
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Affiliation(s)
- J T Real
- Servicio de Endocrinología y Nutrición. Hospital Clínico Universitario. Departamento de Medicina. Universidad de Valencia
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32
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Weiss N, Binder G, Keller C. Mutations in the low-density-lipoprotein receptor gene in German patients with familial hypercholesterolaemia. J Inherit Metab Dis 2000; 23:778-90. [PMID: 11196104 DOI: 10.1023/a:1026704517598] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Familial hypercholesterolaemia (FH) is an autosomal dominant disorder of lipid metabolism characterized by elevated low-density lipoproteins (LDL), the formation of tendon and skin xanthomata and the development of premature coronary atherosclerosis. It is caused by a defect in the receptor-mediated hepatic uptake of LDL due to mutations in the LDL receptor. In 25 FH families with a total of 160 members and in two individuals without available relatives, all of German origin, we identified LDL receptor mutations by a multiplex-PCR-based single-strand conformation polymorphism method followed by direct sequencing. Of the 24 mutations found, 15 are missense mutations, 2 are nonsense mutations, 4 are small deletions or insertions leading to frameshifts, 2 are an in-frame insertion and deletion, respectively, and one is a splice site mutation. Propositi carrying mutations that are known to completely abolish receptor function (nonsense and frameshift mutations, missense mutation V480M) had significantly higher untreated total and LDL-cholesterol levels compared to those patients carrying missense and in-frame insertion mutations of unknown functional consequence, which may lead to either reduced or completely abolished receptor function (11.30+/-1.64 vs 9.76+/-1.50 mmol/L, and 9.39+/-1.23 vs 7.99+/-1.45 mmol/L, respectively). These results confirm the clinical and molecular heterogeneity of FH and the influence of different functional classes of mutations on lipid values.
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Affiliation(s)
- N Weiss
- Medizinische Poliklinik, University of Munich, Germany *.
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33
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Day IN, Whittall RA, O'Dell SD, Haddad L, Bolla MK, Gudnason V, Humphries SE. Spectrum of LDL receptor gene mutations in heterozygous familial hypercholesterolemia. Hum Mutat 2000; 10:116-27. [PMID: 9259195 DOI: 10.1002/(sici)1098-1004(1997)10:2<116::aid-humu4>3.0.co;2-i] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Familial hypercholesterolemia by usual definition reflects mutations of the LDL-receptor gene. Extensive molecular characterization of mutations ascertained mainly through homozygotes (the Dallas collection) has been presented by Hobbs et al. (Hum Mutat 1:445-446, 1992). This paper catalogues a spectrum of 134 mutations (27 novel mutations in 45 patients, 24 previously described mutations in 89 patients) ascertained through heterozygotes from the analysis of 791 patients with definite, probable, or possible FH, mainly from the UK, using high-throughput modifications of the single-strand conformation polymorphism technique. From a composite database of LDL receptor gene mutations complied from these two sets and from the literature, deductions are made about ascertainment bias, mutation rates, and molecular heterogeneity. Calculations suggest that there may be a large number of rare amino acid variants in the general population not causing classic FH. Approaches to, and feasibility of, molecular diagnostics are considered.
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Affiliation(s)
- I N Day
- Department of Medicine, Rayne Institute, University College of London Medical School, UK
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34
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Assouline L, Leitersdorf E, Lambert M, Reshef A, Feoli-Fonseca JC, Levy E. Identification of two novel LDL receptor gene defects in French-Canadian pediatric population: mutational analysis and biochemical studies. Hum Mutat 2000; 9:555-62. [PMID: 9195230 DOI: 10.1002/(sici)1098-1004(1997)9:6<555::aid-humu9>3.0.co;2-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Familial hypercholesterolemia (FH) is at least twofold more prevalent in French Canadians from Québec than in most Western populations. Although our recent data confirmed this high frequency of heterozygous FH in our pediatric population with hypercholesterolemia, none of the five established molecular defects for the French-Canadian population was detected in 29% of the unrelated French-Canadian children characterized by a persistent increase in LDL (low density lipoprotein receptor) cholesterol and a positive parental history of hyperlipidemia (Assouline et al., 1995). To probe for new mutations, six of these molecularly undiagnosed children were investigated as index patients. By using single-strand conformation polymorphism analysis and DNA sequencing, two novel mutations were identified in two of these subjects: (1) 7-base pair (bp) duplication following nucleotide 681 (according to the cDNA sequence) in exon 4 (681ins7), which causes a frameshift, the introduction of a stop at codon 208, and premature chain termination, and (2) A to G change in exon 8 substituting a tyrosine for a cysteine at amino acid 354 (Y354C). A third subject carried the recently reported exon 10 mutation (Y468X), whereas the remaining three patients demonstrated various known polymorphisms with no effect on gene product. Rapid molecular assays were developed to detect the two new mutations as well as the Y468X mutation. Screening of our cohort showed heterozygosity in 1/88, in 2/88, and in 2/88 of patients for the 681ins7, the Y354C, and the Y468X mutations, respectively.
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Affiliation(s)
- L Assouline
- Department of Nutrition, Hôpital Ste-Justine, Université de Montreal, Québec, Canada
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35
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Gudnason V, Sigurdsson G, Nissen H, Humphries SE. Common founder mutation in the LDL receptor gene causing familial hypercholesterolaemia in the Icelandic population. Hum Mutat 2000; 10:36-44. [PMID: 9222758 DOI: 10.1002/(sici)1098-1004(1997)10:1<36::aid-humu5>3.0.co;2-k] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Haplotype analysis in 18 apparently unrelated families with familial hypercholesterolaemia (FH) in Iceland has identified at least five different chromosomes cosegregating with hypercholesterolaemia. The most common haplotype was identified in 11 of the 18 families, indicating a responsible for FH in the Icelandic population. By using single-strand conformation polymorphism (SSCP) and direct sequencing of amplified DNA, we identified a novel mutation (a T to a C) in the second nucleotide in the 5' part of intron 4 in the LDL receptor gene. This mutation was present in approximately 60% of the FH families (10/18), supporting the prediction of a common founder. These families could be traced to a common ancestor in half of the cases by going back no further than the eighteenth century. The mutation was predicted to affect correct splicing of exon 4, and analysis at the cellular level demonstrated an abnormal mRNA containing intron 4 sequence in lymphoblastoid cells from a patient carrying this mutation. Translation of the mRNA would lead to a premature stop codon and a truncated nonfunctional protein of 285 amino acids. The novel sequence change created a new restriction site for the restriction endonuclease NlaIII, and using this assay, 29 unrelated individuals with possible FH attending a lipid clinic for treatment were examined for this mutation. Two individuals in this group of patients were found to be carriers of this mutation, supporting the suggestion of a founder mutation. Using this assay for the detection of FH in the Icelandic population should identify > 60% of these individuals.
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Affiliation(s)
- V Gudnason
- Department of Medicine, University College London Medical School, Rayne Institute, UK
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36
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Sijbrands EJ, Westendorp RG, Paola Lombardi M, Havekes LM, Frants RR, Kastelein JJ, Smelt AH. Additional risk factors influence excess mortality in heterozygous familial hypercholesterolaemia. Atherosclerosis 2000; 149:421-5. [PMID: 10729393 DOI: 10.1016/s0021-9150(99)00336-6] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Life expectancy of patients with familial hypercholesterolaemia is decreased. Some untreated patients reach a normal life span and, therefore, additional risk factors and the type of mutation in the low-density lipoprotein (LDL) receptor gene are likely to influence the clinical outcome. We determined all cause mortality in kindreds with the disorder, who were untreated, in order to study (a) additional risk factors for coronary artery disease (CAD) and (b) the types of LDL receptor gene mutations that may contribute to a poor prognosis. The mortality in all 855 first-degree relatives of 113 unrelated patients was compared to the Dutch population after standardisation for age, gender, and calendar period. Analyses restricted to affected relatives could have underestimated the mortality risk due to lack of information about severe cases, who died prematurely. Therefore, all first-degree relatives were analysed and as a result the standardised mortality ratios (SMRs) exhibit only 50% of the excess mortality from familial hypercholesterolaemia. We observed 190 deaths in 32048 person-years leading to an overall SMR of 1.34 (95% confidence interval (CI) 1. 16-1.55, P=0.001). High excess mortality occurred in males between age 40 and 54 (SMR 2.34, 95% CI 1.60-3.31, P<0.001). The excess mortality decreased during the last decades. This change of mortality over calendar time shows that additional risk factors modulate the mortality from the disorder. The SMR of 62 families referred with premature CAD was 1.62 (95% CI 1.32-1.93, P<0.001) and the SMR was 1.10 (95% CI 0.86-1.34, P=0.4) in 51 families without premature CAD. The mortality risk of kindreds with null alleles was similar to that of kindreds with other mutations. In conclusion, the burden of the untreated disorder occurred mainly among middle-aged males and was not influenced by the type of mutation. Additional risk factors increased excess mortality significantly and are highlighted by the presence of premature CAD among first-degree relatives. This underscores the need for active identification of all hypercholesterolaemic relatives of such patients.
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Affiliation(s)
- E J Sijbrands
- Department of General Internal Medicine, Leiden University Medical Center, Leiden, The Netherlands.
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37
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Raungaard B, Jensen HK, Brorholt-Petersen JU, Heath F, Faergeman O. Functional characterization of two low density lipoprotein receptor gene mutations by fluorescence flow cytometric assessment of receptor activity in stimulated human T-lymphocytes. Clin Genet 2000; 57:110-5. [PMID: 10735631 DOI: 10.1034/j.1399-0004.2000.570204.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
We report a functional characterization of the W23X and W66G low density lipoprotein (LDL) receptor gene mutations. The authors used two-color fluorescence flow cytometry to measure LDL receptor activity in stimulated T-lymphocytes, prepared from patients heterozygous for the W23X or W66G mutation, and compared the results with measurements of LDL receptor activity in stimulated T-lymphocytes prepared from unrelated healthy control subjects. It was found that the W23X mutation significantly reduced LDL receptor expression and LDL binding and internalization, and that the W66G mutation significantly reduced LDL receptor expression and LDL binding. LDL internalization in patients heterozygous for the W66G mutation was not significantly reduced. The data support the concepts that the W23X mutation prevents production of LDL receptors (class I) and that the W66G mutation produces LDL receptors unable to recycle normally in cells (class V).
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Affiliation(s)
- B Raungaard
- Department of Internal Medicine and Cardiology, Aarhus Amtssygehus University Hospital, Denmark.
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38
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Heath KE, Gudnason V, Humphries SE, Seed M. The type of mutation in the low density lipoprotein receptor gene influences the cholesterol-lowering response of the HMG-CoA reductase inhibitor simvastatin in patients with heterozygous familial hypercholesterolaemia. Atherosclerosis 1999; 143:41-54. [PMID: 10208479 DOI: 10.1016/s0021-9150(98)00274-3] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
In a genetically heterogeneous group of 109 patients with a clinical diagnosis of heterozygous familial hypercholesterolaemia (FH), the influence of gender, apolipoprotein (apo) E genotype and the type of molecular defect in the LDL-receptor (LDLR) gene on the reduction of plasma LDL-cholesterol levels to treatment with a HMG-CoA reductase inhibitor (simvastatin) were studied. Response was determined as the percentage fall in LDL-cholesterol from untreated levels and as the proportion of patients where levels fell below 4.9 or 4.1 mmol/l. Of the patients, 86 individuals had tendon xanthomata (TX+) and a diagnosis of 'definite' FH and these individuals presented with a significantly higher untreated LDL-cholesterol compared to the 23 individuals who did not have xanthomas (TX-) and a diagnosis of 'probable' FH (8.14+/-0.19 vs. 6.81+/-0.25, P= 0.001). Overall, HMG-CoA reductase inhibitor doses of 10, 20 or 40 mg/day resulted in a significant fall of LDL-cholesterol levels of 29, 39 and 49%, but at all doses those with TX had significantly higher levels than those without, and significantly fewer TX + patients achieved LDL-cholesterol levels below 4.9 or 4.1 mmol/l than the TX - group (P < 0.05 at each dose). In the TX+ group the response to treatment was of similar magnitude in men and women and in patients with different apoE genotype. In the 'probable' FH probands only three mutations were identified (detection rate 13%), one in the LDLR gene and two in the APOB gene, a detection rate significantly lower (P= 0.02) than in the 'definite' FH probands where 28 mutations were detected (detection rate 37%). In the TX + patients where no mutation was detected, treatment resulted in a greater proportion achieving LDL-cholesterol levels below 4.9 and 4.1 mmol/l compared to those with any LDLR mutation, this difference was close to statistical significance at the 4.9 mmol/l threshold at 10 mg/day (41 vs. 13%, P = 0.058). For the 14 patients with an LDLR mutation that was predicted to be 'severe', fewer achieved LDL-cholesterol levels below 4.9 or 4.1 mmol/l at each dosage compared to the 16 individuals with 'mild' mutations, and this difference was statistically significant at the maximal dosage of 40 mg/day (P = 0.018). Thus although characterisation of the molecular defect in FH patients may not be relevant to their immediate clinical management, those with a particular mutation may need more aggressive lipid-lowering treatment to reach LDL-cholesterol levels recommended to reduce the risk of coronary heart disease (CHD).
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Affiliation(s)
- K E Heath
- Centre for Genetics of Cardiovascular Disorders, Department of Medicine, The Rayne Institute, University College London Medical School, UK.
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39
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Tonstad S, Joakimsen O, Stensland-Bugge E, Ose L, Bønaa KH, Leren TP. Carotid intima-media thickness and plaque in patients with familial hypercholesterolaemia mutations and control subjects. Eur J Clin Invest 1998; 28:971-9. [PMID: 9893006 DOI: 10.1046/j.1365-2362.1998.00399.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND In individuals with familial hypercholesterolaemia (FH), ultrasonographic measurement of carotid intima-media thickness (IMT) and plaque may provide a non-invasive assessment of cardiovascular risk. METHODS We examined carotid artery IMT and its determinants in 79 non-smoking, normotensive, treated men and women with FH aged 26-46 years, and in 79 non-smoking, normotensive sex-, age- and body mass index-matched control subjects. FH was verified by molecular genetic analyses. The underlying mutation in the low-destiny lipoprotein receptor gene included a splice-site mutation, mutations predicted or shown to lead to class 2B mutations or other mutations that probably represent class I mutations (null alleles). RESULTS The carotid bifurcation and common carotid artery IMT was increased in men with FH compared with control subjects (0.81 +/- 0.15 mm vs. 0.74 +/- 0.19 mm and 0.61 +/- 0.13 mm vs. 0.55 +/- 0.14 mm respectively; P < 0.05). The carotid bifurcation IMT was increased in women with FH compared with control subjects (0.74 +/- 0.17 vs. 0. 66 +/- 0.15; P = 0.005). More subjects with FH had carotid plaque (54% vs. 14%; P = 0.0001). In multivariate analysis, male gender, level of low-density lipoprotein-cholesterol, cholesterol-years score and xanthoma were associated with IMT and plaque in subjects with FH. FH subjects with class 2B mutations had lower cholesterol levels than subjects with mutations belonging to the other classes. They also had a tendency towards a decreased common carotid artery IMT. CONCLUSION These findings confirm the importance of gender, xanthoma and lifetime cholesterol levels in relation to carotid atherosclerosis in FH. Whether the type of mutation causing FH modulates carotid artery IMT and plaque requires further study.
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40
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Abstract
It is now possible to identify the specific gene defect in the majority of patients with familial hypercholesterolaemia. A potential benefit of this knowledge, in addition to helping with family screens, is to be able to predict the future clinical course. In order to do this, detailed genotype/phenotype correlation studies are required.
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Affiliation(s)
- P Nicholls
- Department of Medicine, Royal Victoria Hospital, Belfast, UK
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41
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Lee WK, Haddad L, Macleod MJ, Dorrance AM, Wilson DJ, Gaffney D, Dominiczak MH, Packard CJ, Day IN, Humphries SE, Dominiczak AF. Identification of a common low density lipoprotein receptor mutation (C163Y) in the west of Scotland. J Med Genet 1998; 35:573-8. [PMID: 9678702 PMCID: PMC1051368 DOI: 10.1136/jmg.35.7.573] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Familial hypercholesterolaemia (FH) is an autosomal codominant disorder characterised by high levels of LDL cholesterol and a high incidence of coronary artery disease. Our aims were to track the low density lipoprotein receptor (LDLR) gene in individual families with phenotypic FH and to identify and characterise any mutations of the LDLR gene that may be common in the west of Scotland FH population using single strand conformational polymorphism analysis (SSCP). Patient samples consisted of 80 heterozygous probands with FH, 200 subjects who were related to the probands, and a further 50 normal, unrelated control subjects. Tracking of the LDLR gene was accomplished by amplification of a 19 allele tetranucleotide microsatellite that is tightly linked to the LDLR gene locus. Primers specific for exon 4 of the LDLR gene were used to amplify genomic DNA and used for SSCP analysis. Any PCR products with different migration patterns as assessed by SSCP were then sequenced directly. In addition to identifying probands with a common mutation, family members were screened using a forced restriction site assay and analysed using microplate array diagonal gel electrophoresis (MADGE). Microsatellite D19S394 analysis was informative in 20 of 23 families studied. In these families there was no inconsistency with segregation of the FH phenotype with the LDLR locus. Of the FH probands, 15/80 had a mutant allele as assessed by SSCP using three pairs of primers covering the whole of exon 4 of the LDLR gene. Direct DNA sequencing showed that 7/15 of the probands had a C163Y mutation. Using a PCR induced restriction site assay for the enzyme RsaI and MADGE, it was determined that the C163Y mutation cosegregated with the FH phenotype in family members of the FH probands. This mutant allele was not present in any of the control subjects. Microsatellite analysis has proven useful in tracking the LDLR gene and could be used in conjunction with LDL cholesterol levels to diagnose FH, especially in children and young adults where phenotypic diagnosis can be difficult.
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Affiliation(s)
- W K Lee
- Department of Medicine and Therapeutics, Gardiner Institute, Western Infirmary, Glasgow, UK
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42
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Sijbrands EJ, Lombardi MP, Westendorp RG, Leuven JA, Meinders AE, Van der Laarse A, Frants RR, Havekes LM, Smelt AH. Similar response to simvastatin in patients heterozygous for familial hypercholesterolemia with mRNA negative and mRNA positive mutations. Atherosclerosis 1998; 136:247-54. [PMID: 9543095 DOI: 10.1016/s0021-9150(97)00216-5] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
In patients heterozygous for familial hypercholesterolemia, the low-density lipoprotein (LDL) cholesterol lowering effect of beta-hydroxy-beta-methylglutaryl coenzyme A reductase inhibitors may depend on the nature of the mutation in the LDL receptor gene. To test this hypothesis, we compared the response to simvastatin, 20 mg daily for 9 weeks, between heterozygous carriers of functionally different classes of mutations, i.e. mRNA negative or mRNA positive mutations. Out of 116 consecutive, unrelated patients with familial hypercholesterolemia, 27 patients were selected for molecular analyses: 14 patients with mRNA negative and 13 with mRNA positive mutations. Before simvastatin treatment, patients with mRNA negative mutations had higher levels of LDL cholesterol, lower levels of high-density lipoprotein (HDL) cholesterol and significantly more often tendon xanthomas, compared to patients with mRNA positive mutations. Simvastatin reduced the mean fasting LDL cholesterol levels to a similar percentage in the mRNA negative and mRNA positive patients (37, 36%, respectively, 95% CI of difference--8 to 5%, P = 0.2). This effect was similar to the 37% decrease observed in our total series of patients with familial hypercholesterolemia (n = 116). The increase in mean concentration of HDL cholesterol was greater in the mRNA negative group than in the mRNA positive group (16, 0%, respectively, 95%, CI of difference 8-25%, P = 0.002) independent of the response of total triglycerides to simvastatin. The percentage LDL cholesterol lowering response varied among multiple carriers of the same mutation, even in the case of mRNA negative mutations. We conclude that the percentage LDL lowering response to simvastatin treatment was similar in patients with mRNA negative and mRNA positive mutations. Moreover, variation of this response within multiple carriers of the same mutation suggests an influence of additional factors.
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Affiliation(s)
- E J Sijbrands
- Department of General Internal Medicine, Medical Faculty, Leiden, The Netherlands.
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43
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Jensen HK, Jensen LG, Hansen PS, Faergeman O, Gregersen N. The Trp23-Stop and Trp66-Gly mutations in the LDL receptor gene: common causes of familial hypercholesterolemia in Denmark. Atherosclerosis 1996; 120:57-65. [PMID: 8645371 DOI: 10.1016/0021-9150(95)05680-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Mutations in the gene for the low density lipoprotein (LDL) receptor cause the autosomal dominant disease familial hypercholesterolemia (FH), the prevalence of which is about 0.2% in most populations. By PCR-SSCP analysis and direct sequencing, we identified the receptor-negative Trp23-Stop LDL receptor mutation (FH Cincinnati-5) in 10 of 63 FH probands and the receptor-defective Trp66-Gly LDL receptor mutation (FH French Canadian-4) in another 10 of the 63 FH probands. These two mutations thus account for 30% of diagnosed FH families in Denmark. Comparison of the mean lipid concentrations (unadjusted and adjusted for age), including serum total cholesterol and LDL-cholesterol, showed no significant differences between the two groups of FH heterozygote probands (cholesterol: 10.7 mmol/l vs. 10.7 mmol/l) and between the probands and 16 and 22 non-proband family members with the Trp23-stop (cholesterol: 10.1 mmol/l) ad Trp66-Gly (cholesterol: 10.7 mmol/l) mutations, respectively.
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Affiliation(s)
- H K Jensen
- Center for Medical Molecular Biology, Skejby Sygehus University Hospital, Arhus N, Denmark
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Gudnason V, Muller DP, Lloyd JK, Humphries SE. Response to drugs and diet in a compound heterozygote for familial hypercholesterolaemia. Arch Dis Child 1995; 73:538-40. [PMID: 8546515 PMCID: PMC1511462 DOI: 10.1136/adc.73.6.538] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
A boy with a total plasma cholesterol concentration of 20.9 mmol/l which fell significantly with a low fat diet, cholestyramine and simvastatin, was shown to have two different mutations in the low density lipoprotein receptor gene, demonstrating that some patients with homozygous familial hypercholesterolaemia show a good lipid lowering response to treatment.
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Affiliation(s)
- V Gudnason
- Department of Medicine, Rayne Institute, University College of London Medical School
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Sass C, Giroux LM, Lussier-Cacan S, Davignon J, Minnich A. Unexpected consequences of deletion of the first two repeats of the ligand-binding domain from the low density lipoprotein receptor. Evidence from a human mutation. J Biol Chem 1995; 270:25166-71. [PMID: 7559651 DOI: 10.1074/jbc.270.42.25166] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Heterozygosity for a 5-kilobase (kb) deletion of the first two ligand-binding repeats (exons 2 and 3) of the low density lipoprotein (LDL) receptor (R) gene (LDL-R delta 5kb) confers familial hypercholesterolemia (FH). The FH phenotype is unexpected based on previous site-directed mutagenesis showing that deletion of exons 2 and 3 resulted in little or no defect in LDL-R activity. In the present study, we took unique advantage of the ability to distinguish the LDL-R delta 5kb from the normal receptor on the basis of size, in order to resolve this apparent discrepancy. Fibroblasts from heterozygotes for the LDL-R delta 5kb displayed 50% of normal capacity to bind LDL and beta-VLDL, apparently due to lower receptor number. Cellular mRNA for the delta 5kb allele was at least as abundant as that for the normal allele. Immunoblotting and cell binding assays with anti-LDL-R antibody IgG-4A4 demonstrated normal synthesis and transport of the delta 5kb receptor. Ligand blotting demonstrated that the delta 5kb receptor displayed minimal or no ability to bind LDL or beta-VLDL. Thus, in contrast to transfected cell lines, in human fibroblasts, the first two cysteine rich repeats of the LDL-R appear functionally necessary. These characteristics of the LDL-R delta 5kb in human fibroblasts explain the in vivo phenotype of carriers.
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Affiliation(s)
- C Sass
- Department of Medicine, University of Montreal, Quebec, Canada
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Humphries SE, Peacock RE, Talmud PJ. The genetic determinants of plasma cholesterol and response to diet. BAILLIERE'S CLINICAL ENDOCRINOLOGY AND METABOLISM 1995; 9:797-823. [PMID: 8593126 DOI: 10.1016/s0950-351x(95)80161-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
In general, risk factors for multifactorial disorders such as atherosclerosis and hyperlipidaemia show a continuous distribution in the population, and this is the result of both interaction between genetic variation at genetic loci, and genetic and environmental interaction. Therefore, the investigation of the genetics of intermediate phenotypes such as levels of plasma lipid traits is likely to be particularly informative. Once the genes involved in determining the levels of these phenotypes have been identified, it should be possible to use the information to obtain a better understanding of the way these genetic variations determine the clinical end points. In the population it will be possible to identify a number of polygenes that are having a small effect on determining the trait, but for a particular individual, or the relatives of that individual, only a subset of all these polygenes will determine the level of the trait and therefore the risk of developing the disorder. In general, mutations with a large effect on the trait are rare in the population, By contrast, polymorphisms with a small effect on the trait may be common, such as is found with the effect of the apoE alleles and variation at the apoB gene locus on lipid levels. In the field of hyperlipidaemia and atherosclerosis research, molecular techniques have already given a great deal of information on how specific sequence variations in some of the candidate genes are involved in determining levels of plasma apoproteins, lipoproteins and lipids. As more mutations and sequence variations are identified, this will not only aid our understanding of the underlying pathology, but should be useful for identifying individuals who are at risk of developing atherosclerosis because of their particular genotype or combination of genotypes.
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Affiliation(s)
- S E Humphries
- Department of Medicine, University College London Medical School, Rayne Institute, UK
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Day IN, O'Dell SD, Cash ID, Humphries SE, Weavind GP. Electrophoresis for genotyping: temporal thermal gradient gel electrophoresis for profiling of oligonucleotide dissociation. Nucleic Acids Res 1995; 23:2404-12. [PMID: 7630718 PMCID: PMC307044 DOI: 10.1093/nar/23.13.2404] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Traditional use of an oligonucleotide probe to determine genotype depends on perfect base pairing to a single-stranded target which is stable to a higher temperature than when imperfect binding occurs due to a mismatch in the target sequence. Bound oligonucleotide is detected at a predetermined single temperature 'snapshot' of the melting profile, allowing the distinction of perfect from imperfect base pairing. In heterozygotes, the presence of the alternative sequence must be verified with a second oligonucleotide complementary to the variant. Here we describe a system of real-time variable temperature electrophoresis during which the oligonucleotide dissociates from its target. In 20% polyacrylamide the target strand has minimal mobility and released oligonucleotide migrates extremely quickly so that the 'freed' rather than the 'bound' is displayed. The full profile of oligonucleotide dissociation during gel electrophoresis is represented along the gel track, and a single oligonucleotide is sufficient to confirm heterozygosity, since the profile displays two separate peaks. Resolution is great, with use of short track lengths enabling analysis of dense arrays of samples. Each gel track can contain a different target or oligonucleotide and the temperature gradient can accommodate oligonucleotides of different melting temperatures. This provides a convenient system to examine the interaction of many different oligonucleotides and target sequences simultaneously and requires no prior knowledge of the mutant sequence(s) nor of oligonucleotide melting temperatures. The application of the technique is described for screening of a hotspot for mutations in the LDL receptor gene in patients with familial hypercholesterolaemia.
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Affiliation(s)
- I N Day
- Department of Medicine, University College London Medical School, Rayne Institute, UK
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Whittall R, Gudnason V, Weavind GP, Day LB, Humphries SE, Day IN. Utilities for high throughput use of the single strand conformational polymorphism method: screening of 791 patients with familial hypercholesterolaemia for mutations in exon 3 of the low density lipoprotein receptor gene. J Med Genet 1995; 32:509-15. [PMID: 7562961 PMCID: PMC1050541 DOI: 10.1136/jmg.32.7.509] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
We have modified several aspects of the single strand conformational polymorphism (SSCP) method to increase the speed with which the technique can be used for mutation detection. The methods attain high resolution of small mobility differences using long (30 cm) gels and use a modified polymerase reaction to maximise detection sensitivity using a minimised quantity of 32P. By using custom cut "sharktooth" combs (4.5 mm between teeth) as the slot formers, commercially available multichannel pipettes (9 mm tip to tip) can be used to load eight or 12 samples at a time from standard microtitre plates. PCR products that have been prepared and radiolabelled using simplified protocols are loaded on to the gel, and after a precalculated time of electrophoresis another set of samples can be loaded, either with combs moved across 2.25 mm or onto the same gel tracks. The run conditions are calculated so that there is no overlap between the bands produced by the two loadings, thus doubling the amount of information that can be gained from one gel. A computer program has been developed to solve equations to determine suitable timings for repetitive loadings. Finally, a modification of the gel pouring system is described so that two gels can be poured between three standard glass plates, with both gels run simultaneously. Of the order of 1000 PCR reactions can be prepared and analysed in 24 man hours using five 40 cm x 30 cm gel tanks. The application of these techniques is described to detect SSCPs in exon 3 of the low density lipoprotein receptor (LDLR) gene in 791 patients with familial hypercholesterolaemia (FH). Eight different SSCP patterns were seen, one of which was caused by the previously described E80K mutation, which was present in 11 patients (1.4%). In total, 32 patients (4%) were identified with exon 3 mutations.
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Affiliation(s)
- R Whittall
- Department of Medicine, Rayne Institute, University College of London Medical School, UK
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Soutar AK. Familial hypercholesterolaemia: Mutations in the gene for the low-density-lipoprotein receptor. ACTA ACUST UNITED AC 1995; 1:90-7. [PMID: 17607901 DOI: 10.1016/s1357-4310(95)92412-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Familial hypercholesterolaemia is a co-dominant inherited disorder of lipoprotein metabolism, in which defects in the gene for the low-density-lipoprotein (LDL) receptor result in a twofold increase in the plasma concentration of cholesterol and moderate-to-severe premature coronary heart disease. Many mutations in the gene for the LDL receptor that have different effects on the structure and function of this multifunctional protein have been found, but it is not yet clear whether the nature of the mutation determines the severity of the disorder. This question is being answered by comparing patients with well-characterized mutations, and recent work suggests that other genetic or environmental factors may be important in modulating the effect of the defect in LDL-receptor function in patients who are heterozygous for the disorder.
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Affiliation(s)
- A K Soutar
- Lipoprotein Team, MRC Clinical Sciences Centre, Royal Postgraduate Medical School, Hammersmith Hospital, Du Cane Road, London, UK.
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Affiliation(s)
- M J Halpern
- Instituto Superior de Ciências da Saúde-Sul, Quinta da Granja, Monte de Caparica, Portugal
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