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Yip MK, Kwan EYW, Leung JYY, Lau EYF, Poon WT. Genetic Spectrum and Cascade Screening of Familial Hypercholesterolemia in Routine Clinical Setting in Hong Kong. Genes (Basel) 2023; 14:2071. [PMID: 38003014 PMCID: PMC10671696 DOI: 10.3390/genes14112071] [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: 10/31/2023] [Revised: 11/11/2023] [Accepted: 11/12/2023] [Indexed: 11/26/2023] Open
Abstract
Familial hypercholesterolemia (FH) is a prevalent but often underdiagnosed monogenic disorder affecting lipoprotein metabolism, and genetic testing for FH has not been widely conducted in Asia in the past. In this cross-sectional study of 31 probands (19 adults and 12 children) and an addition of 15 individuals (12 adults and 3 children), who underwent genetic testing and cascade screening for FH, respectively, during the period between February 2015 and July 2023, we identified a total of 25 distinct LDLR variants in 71.0% unrelated probands. Among the adult proband cohort, a higher proportion of genetically confirmed cases exhibited a positive family history of premature cardiovascular disease. Treatment intensity required to achieve an approximate 50% reduction in pretreatment low-density lipoprotein cholesterol (LDL-C) exhibited potentially better diagnostic performance compared to pretreatment LDL-C levels, Dutch Lipid Clinic Network Diagnostic Criteria (DLCNC) score, and modified DLCNC score. Adult individuals identified through cascade screening demonstrated less severe phenotypes, and fewer of them met previously proposed local criteria for FH genetic testing compared to the probands, indicating that cascade screening played a crucial role in the early detection of new cases that might otherwise have gone undiagnosed. These findings underscore the significance of genetic testing and cascade screening in the accurate identification and management of FH cases.
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Affiliation(s)
- Man-Kwan Yip
- Department of Clinical Pathology, Pamela Youde Nethersole Eastern Hospital, Chai Wan, Hong Kong, China
| | - Elaine Yin-Wah Kwan
- Department of Paediatrics and Adolescent Medicine, Pamela Youde Nethersole Eastern Hospital, Chai Wan, Hong Kong, China;
| | - Jenny Yin-Yan Leung
- Department of Medicine and Geriatrics, Ruttonjee Hospital, Wan Chai, Hong Kong, China;
| | - Emmy Yuen-Fun Lau
- Department of Medicine, Pamela Youde Nethersole Eastern Hospital, Chai Wan, Hong Kong, China
| | - Wing-Tat Poon
- Department of Clinical Pathology, Pamela Youde Nethersole Eastern Hospital, Chai Wan, Hong Kong, China
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2
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Jingxin S, Shitong C. Expanding the genetic spectrum for Chinese familial hypercholesterolemia population with six genetic mutations identified using a next-generation sequencing-based laboratory-developed screening test. Mol Genet Genomic Med 2022; 10:e2070. [PMID: 36226792 PMCID: PMC9747561 DOI: 10.1002/mgg3.2070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 09/27/2022] [Accepted: 09/30/2022] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND This study was to reveal the prevalence of definite familial hypercholesterolemia (FH) in the hospital-visiting population, determine the pathogenic mutation detection rate in clinically diagnosed definite FH patients, and expand the FH mutation spectrum in China. METHODS Blood lipid profiles of 41,803 patients visiting the hospital were investigated and 4967 patients with clinical diagnoses of other metabolic diseases were excluded. One hundred and seventy-three (0.41%) received a definite diagnosis of FH according to the Dutch Lipid Clinical Network Criteria-Chinese Revised Version (DLCN-CRV), and 18 patients subsequently agreed to undergo genetic testing. A next-generation sequencing (NGS)-based laboratory-developed test covering the exonic regions of 24 lipid metabolism-related genes was conducted alongside in silico analyses to identify possible FH mutations in 16 definite FH patients, according to the American College of Medical Genetics and Genomics (ACMG) criteria. Sanger sequencing was used to confirm mutations, and SWISS-MODEL was used to simulate the molecular structures of the confirmed protein-carrying mutations. RESULTS The FH prevalence was 0.41% for the 41,803 individuals (DLCN-CRV grade >8) and 25% of definite FH patients carried six FH pathogenic mutations (≥ACMG Class 4). All genetic variants were confirmed by Sanger sequencing. Five pathogenic variants on the LDLR gene (NM_000527: c.C1783T: p.R595W, c.T493G: p.W165G, c.G1879A: p.A627T, c.G682T: p.E228X, and exon10: c.G1432A: p.G478R) and one pathogenic variant on APOB (NM_000384: c.C10579T: p.R3527W) in 25% of the identified definite FH patients. Two pathogenic mutations, c.T493G (p.W165G) and c.C1783T (p.R595W), were added to the current genetic spectrum of FH in China. CONCLUSION This study contributes to improving the current FH detection rate and genetic screening strategies; it provides new directions for treatment, management, and drug development.
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Affiliation(s)
- Shan Jingxin
- Department of Laboratory MedicineThe First Hospital of China Medical UniversityShenyangChina
- Department of Biomedical EngineeringHE UniversityShenyangChina
| | - Cheng Shitong
- Department of Laboratory MedicineThe First Hospital of China Medical UniversityShenyangChina
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3
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Shu HY, Zhang W, Zheng CC, Gao MY, Li YC, Wang YG. Identification and Functional Characterization of a Low-Density Lipoprotein Receptor Gene Pathogenic Variant in Familial Hypercholesterolemia. Front Genet 2021; 12:650077. [PMID: 34497632 PMCID: PMC8419346 DOI: 10.3389/fgene.2021.650077] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Accepted: 06/01/2021] [Indexed: 11/13/2022] Open
Abstract
We report a single-point variant of low-density lipoprotein receptor (LDLR) in a Chinese proband with a clinical diagnosis of familial hypercholesterolemia (FH) with a comprehensive functional analysis. Target exome capture-based next-generation sequencing was used for sequencing and identification of genomic variants in the LDLR gene. The expression, cellular location, and function of the mutant LDLR were analyzed. Sequencing of LDLR in FH patients indicated a point variant of single-base substitution (G < A) at a position of 2389 in the 16th exon, which led to a loss of the 16th exon in the LDLR messenger RNA. This genomic variant was found to cause exon 16 deletion in the mutant LDLR protein. Subsequent functional analyses showed that the mutant LDLR was retained in the Golgi apparatus and rarely expressed in the cellular membranes of HepG2 cells. Accordingly, the intake ability of HepG2 cells with the mutant LDLR was significantly reduced (P < 0.05). In conclusion, our results suggest that a mutant with a single-base substitution (c. 2389G > A) in the 16th exon of the LDLR gene was associated with miscleavage of messenger RNA and the retention of mutant LDLR in the Golgi apparatus, which revealed a pathogenic variant in LDLR underlying the pathogenesis of FH.
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Affiliation(s)
- Hong-Yan Shu
- Department of Endocrinology and Metabolic Diseases, Zibo Municipal Hospital, Zibo, China
| | - Wei Zhang
- Department of Endocrinology and Metabolic Diseases, Zibo Municipal Hospital, Zibo, China
| | - Cong-Cong Zheng
- Department of Endocrinology and Metabolic Diseases, Zibo Municipal Hospital, Zibo, China
| | - Man-Yun Gao
- Department of Endocrinology and Metabolic Diseases, Zibo Municipal Hospital, Zibo, China
| | - Yong-Cun Li
- Department of Endocrinology and Metabolic Diseases, Zibo Municipal Hospital, Zibo, China
| | - Yan-Gang Wang
- Department of Endocrinology and Metabolic Diseases, The Affiliated Hospital of Qingdao University, Qingdao, China
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4
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Jackson CL, Zordok M, Kullo IJ. Familial hypercholesterolemia in Southeast and East Asia. Am J Prev Cardiol 2021; 6:100157. [PMID: 34327494 PMCID: PMC8315601 DOI: 10.1016/j.ajpc.2021.100157] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 02/01/2021] [Accepted: 02/07/2021] [Indexed: 12/11/2022] Open
Abstract
Even though at least a quarter of the world's FH population lives in Southeast and East Asia, there are substantial gaps in knowledge regarding the epidemiology of FH due to low awareness, the absence of national screening programs, and limited availability of genetic testing. We discuss the most recent and relevant information available related to diagnostic criteria, prevalence, awareness, clinical characteristics, genetic epidemiology, and treatment in the FH population of Southeast and East Asia. Increasing awareness and improving the diagnosis and management of FH will reduce the burden of premature CHD in these regions of the world.
Familial hypercholesterolemia (FH) is a relatively common autosomal dominant disorder associated with a significantly increased risk of coronary heart disease (CHD). Most (~85–90%) cases are due to pathogenic variants in the LDL-receptor gene (LDLR), while the remaining are due to pathogenic variants in the apolipoprotein B (APOB) and proprotein convertase subtilisin/kexin type 9 (PCSK9) genes, though the proportion may vary depending on geographic location. Even though at least a quarter of the world's FH population lives in Southeast and East Asia, there are substantial gaps in knowledge regarding the epidemiology of FH due to low awareness, the absence of national screening programs, and limited availability of genetic testing. In this review, we discuss the most recent and relevant information available related to diagnostic criteria, prevalence, awareness, clinical characteristics, genetic epidemiology, and treatment in the FH population of Southeast and East Asia. Increasing awareness and improving the diagnosis and management of FH will reduce the burden of premature CHD in these regions of the world.
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Affiliation(s)
| | - Magdi Zordok
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN USA
| | - Iftikhar J Kullo
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN USA
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Miroshnikova VV, Romanova OV, Ivanova ON, Fedyakov MA, Panteleeva AA, Barbitoff YA, Muzalevskaya MV, Urazgildeeva SA, Gurevich VS, Urazov SP, Scherbak SG, Sarana AM, Semenova NA, Anisimova IV, Guseva DM, Pchelina SN, Glotov AS, Zakharova EY, Glotov OS. Identification of novel variants in the LDLR gene in Russian patients with familial hypercholesterolemia using targeted sequencing. Biomed Rep 2020; 14:15. [PMID: 33269076 PMCID: PMC7694592 DOI: 10.3892/br.2020.1391] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Accepted: 10/09/2020] [Indexed: 12/12/2022] Open
Abstract
Familial hypercholesterolemia (FH) is caused by mutations in various genes, including the LDLR, APOB and PSCK9 genes; however, the spectrum of these mutations in Russian individuals has not been fully investigated. In the present study, mutation screening was performed on the LDLR gene and other FH-associated genes in patients with definite or possible FH, using next-generation sequencing. In total, 59 unrelated patients were recruited and sorted into two separate groups depending on their age: Adult (n=31; median age, 49; age range, 23-70) and children/adolescent (n=28; median age, 11; age range, 2-21). FH-associated variants were identified in 18 adults and 25 children, demonstrating mutation detection rates of 58 and 89% for the adult and children/adolescent groups, respectively. In the adult group, 13 patients had FH-associated mutations in the LDLR gene, including two novel variants [NM_000527.4: c.433_434dupG p.(Val145Glyfs*35) and c.1186G>C p.(Gly396Arg)], 3 patients had APOB mutations and two had ABCG5/G8 mutations. In the children/adolescent group, 21 patients had FH-causing mutations in the LDLR gene, including five novel variants [NM_000527.4: c.325T>G p.(Cys109Gly), c.401G>C p.(Cys134Ser), c.616A>C p.(Ser206Arg), c.1684_1691delTGGCCCAA p.(Pro563Hisfs*14) and c.940+1_c.940+4delGTGA], and 2 patients had APOB mutations, as well as ABCG8 and LIPA mutations, being found in different patients. The present study reported seven novel LDLR variants considered to be pathogenic or likely pathogenic. Among them, four missense variants were located in the coding regions, which corresponded to functional protein domains, and two frameshifts were identified that produced truncated proteins. These variants were observed only once in different patients, whereas a splicing variant in intron 6 (c.940+1_c.940+4delGTGA) was detected in four unrelated individuals. Previously reported variants in the LDLR, APOB, ABCG5/8 and LIPA genes were observed in 33 patients. The LDLR p.(Gly592Glu) variant was detected in 6 patients, representing 10% of the FH cases reported in the present study, thus it may be a major variant present in the Russian population. In conclusion, the present study identified seven novel variants of the LDLR gene and broadens the spectrum of mutations in FH-related genes in the Russian Federation.
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Affiliation(s)
- Valentina V Miroshnikova
- Laboratory of Human Molecular Genetics, Molecular and Radiation Biophysics Department, Petersburg Nuclear Physics Institute, National Research Center 'Kurchatov Institute', Gatchina 188300, Russian Federation
| | - Olga V Romanova
- Genetic Laboratory of City Hospital No. 40, Saint-Petersburg, 197706, Russian Federation.,Department of Genomic Medicine, D.O. Ott Research Institute of Obstetrics, Gynaecology and Reproduction, Saint-Petersburg 199034, Russian Federation
| | - Olga N Ivanova
- Laboratory of Hereditary Metabolic Diseases and Counselling Unit of Federal State Budgetary Institution 'Research Centre for Medical Genetics', Moscow 115522, Russian Federation
| | - Mikhail A Fedyakov
- Genetic Laboratory of City Hospital No. 40, Saint-Petersburg, 197706, Russian Federation
| | - Alexandra A Panteleeva
- Laboratory of Human Molecular Genetics, Molecular and Radiation Biophysics Department, Petersburg Nuclear Physics Institute, National Research Center 'Kurchatov Institute', Gatchina 188300, Russian Federation.,Kurchatov Complex of NBICS Nature-Like Technologies of National Research Center 'Kurchatov Institute', Moscow 123182, Russian Federation.,Molecular-Genetic and Nanobiological Technology Department of Scientific Research Center, Pavlov First Saint-Petersburg State Medical University, Saint-Petersburg 197022, Russian Federation.,Bioinformatics Institute, Saint-Petersburg 197342, Russian Federation
| | - Yury A Barbitoff
- Department of Genomic Medicine, D.O. Ott Research Institute of Obstetrics, Gynaecology and Reproduction, Saint-Petersburg 199034, Russian Federation.,Bioinformatics Institute, Saint-Petersburg 197342, Russian Federation
| | - Maria V Muzalevskaya
- Department for Atherosclerosis and Lipid Disorders of North-Western District Scientific and Clinical Center Named After L.G. Sokolov FMBA, Saint-Petersburg 194291, Russian Federation.,Medical Faculty of Saint-Petersburg State University, Saint-Petersburg 199034, Russian Federation
| | - Sorejya A Urazgildeeva
- Department for Atherosclerosis and Lipid Disorders of North-Western District Scientific and Clinical Center Named After L.G. Sokolov FMBA, Saint-Petersburg 194291, Russian Federation.,Medical Faculty of Saint-Petersburg State University, Saint-Petersburg 199034, Russian Federation
| | - Victor S Gurevich
- Department for Atherosclerosis and Lipid Disorders of North-Western District Scientific and Clinical Center Named After L.G. Sokolov FMBA, Saint-Petersburg 194291, Russian Federation.,Medical Faculty of Saint-Petersburg State University, Saint-Petersburg 199034, Russian Federation
| | - Stanislav P Urazov
- Genetic Laboratory of City Hospital No. 40, Saint-Petersburg, 197706, Russian Federation
| | - Sergey G Scherbak
- Genetic Laboratory of City Hospital No. 40, Saint-Petersburg, 197706, Russian Federation
| | - Andrey M Sarana
- Medical Faculty of Saint-Petersburg State University, Saint-Petersburg 199034, Russian Federation
| | - Natalia A Semenova
- Laboratory of Hereditary Metabolic Diseases and Counselling Unit of Federal State Budgetary Institution 'Research Centre for Medical Genetics', Moscow 115522, Russian Federation
| | - Inga V Anisimova
- Laboratory of Hereditary Metabolic Diseases and Counselling Unit of Federal State Budgetary Institution 'Research Centre for Medical Genetics', Moscow 115522, Russian Federation
| | - Darya M Guseva
- Laboratory of Hereditary Metabolic Diseases and Counselling Unit of Federal State Budgetary Institution 'Research Centre for Medical Genetics', Moscow 115522, Russian Federation
| | - Sofya N Pchelina
- Laboratory of Human Molecular Genetics, Molecular and Radiation Biophysics Department, Petersburg Nuclear Physics Institute, National Research Center 'Kurchatov Institute', Gatchina 188300, Russian Federation.,Kurchatov Complex of NBICS Nature-Like Technologies of National Research Center 'Kurchatov Institute', Moscow 123182, Russian Federation.,Molecular-Genetic and Nanobiological Technology Department of Scientific Research Center, Pavlov First Saint-Petersburg State Medical University, Saint-Petersburg 197022, Russian Federation
| | - Andrey S Glotov
- Genetic Laboratory of City Hospital No. 40, Saint-Petersburg, 197706, Russian Federation.,Department of Genomic Medicine, D.O. Ott Research Institute of Obstetrics, Gynaecology and Reproduction, Saint-Petersburg 199034, Russian Federation
| | - Ekaterina Y Zakharova
- Laboratory of Hereditary Metabolic Diseases and Counselling Unit of Federal State Budgetary Institution 'Research Centre for Medical Genetics', Moscow 115522, Russian Federation
| | - Oleg S Glotov
- Genetic Laboratory of City Hospital No. 40, Saint-Petersburg, 197706, Russian Federation.,Department of Genomic Medicine, D.O. Ott Research Institute of Obstetrics, Gynaecology and Reproduction, Saint-Petersburg 199034, Russian Federation
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6
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Huang CC, Charng MJ. Genetic Diagnosis of Familial Hypercholesterolemia in Asia. Front Genet 2020; 11:833. [PMID: 32793292 PMCID: PMC7393677 DOI: 10.3389/fgene.2020.00833] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Accepted: 07/09/2020] [Indexed: 12/31/2022] Open
Abstract
Familial hypercholesterolemia (FH) is a common genetic disease with an incidence of about 1 in 200-500 individuals. Genetic mutations markedly elevate low-density lipoprotein cholesterol and atherosclerotic cardiovascular disease (ASCVD) in FH patients. With advances in clinical diagnosis and genetic testing, more genetic mutations have been detected, including those in low-density lipoprotein receptor (LDLR), apolipoprotein B (APOB), proprotein convertase subtilisin/kexin type 9 (PCSK9), and so on. Globally, most FH patients remain undiagnosed, untreated, or inappropriately treated. Recently, there was a Global Call to Action by the Global Familial Hypercholesterolemia Community to reduce the health burden of FH. Asia, despite being the most populous continent with half of the global population, has low FH detection rates compared to Western countries. Therefore, we aimed to review the current status of FH genetic diagnosis in Asia to understand the gaps in FH diagnosis and management in this region.
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Affiliation(s)
- Chin-Chou Huang
- Division of Cardiology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.,Faculty of Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan.,Cardiovascular Research Center, National Yang-Ming University, Taipei, Taiwan.,Institute of Pharmacology, National Yang-Ming University, Taipei, Taiwan
| | - Min-Ji Charng
- Division of Cardiology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.,Faculty of Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan
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7
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Jin W, Zhang Q, Wang B, Pan L, Qin H, Yang D, Zhou X, Du Y, Lin L, Kutryk MJ. Cascade screening for familial hypercholesterolemia-identification of the C308Y mutation in multiple family members and relatives for the first time in mainland China. BMC MEDICAL GENETICS 2019; 20:173. [PMID: 31706281 PMCID: PMC6842482 DOI: 10.1186/s12881-019-0901-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/19/2019] [Accepted: 10/09/2019] [Indexed: 12/31/2022]
Abstract
Background Familial hypercholesterolemia (FH), an autosomal dominant genetic disorder, is underdiagnosed and undertreated. The majority of FH cases are caused by low density lipoprotein receptor (LDL-R) gene mutations. The C308Y mutation in LDL-R results in approximately 70% loss of LDL-R activity, leading to the elevation of low density lipoprotein-cholesterol (LDL-C) and an increased risk of premature coronary heart disease (CHD). The aim of this study was to identify FH cases by cascade screening in family members and relatives of a 37-year old male with premature CHD and hypercholesterolemia. Methods Clinical exam, blood lipid profiling and genomic DNA sequencing of all exons of LDL-R were performed for the proband and his 14 family members and relatives. FH diagnosis was carried out using the Dutch Lipid Clinic Network (DLCN) criteria. Results Lipid profiling showed that 9 individuals, including the proband, had hypercholesterolemia. All these 9 subjects had a G > A substitution at nucleotide 986 in exon 7 resulting in the C308Y mutation as determined by DNA sequencing, and all those carrying the mutation were diagnosed as having definite FH under the DLCN criteria. However, most (7/9) did not have suggestive clinical manifestations of CHD. Conclusions The C308Y mutation was discovered in multiple family members and relatives for the first time in mainland China. Cascade screening is key for the confirmatory diagnosis of FH. Our hypothesis that the C308Y is a common variant in the population of Southern China origin warrants further validation by screening for the C308Y mutation in a large population.
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Affiliation(s)
- Weirong Jin
- Shanghai Human Genome Center, Shanghai, China
| | - Qiuwang Zhang
- Division of Cardiology, Keenan Research Center for Biomedical Science, St. Michael's Hospital, University of Toronto, Toronto, Ontario, Canada
| | - Bei Wang
- Department of Cardiology, the Third People's Hospital of Hainan Province, 1154 Jiefang Road, Sanya, 572000, Hainan Province, China
| | - Lili Pan
- Department of Cardiology, the Third People's Hospital of Hainan Province, 1154 Jiefang Road, Sanya, 572000, Hainan Province, China
| | - Hongyou Qin
- Shanghai Human Genome Center, Shanghai, China
| | - Daying Yang
- Department of Cardiology, the Third People's Hospital of Hainan Province, 1154 Jiefang Road, Sanya, 572000, Hainan Province, China
| | - Xiangqun Zhou
- Department of Cardiology, the Third People's Hospital of Hainan Province, 1154 Jiefang Road, Sanya, 572000, Hainan Province, China
| | - Yongcai Du
- Department of Cardiology, the Third People's Hospital of Hainan Province, 1154 Jiefang Road, Sanya, 572000, Hainan Province, China
| | - Ling Lin
- Department of Cardiology, the Third People's Hospital of Hainan Province, 1154 Jiefang Road, Sanya, 572000, Hainan Province, China.
| | - Michael J Kutryk
- Division of Cardiology, Keenan Research Center for Biomedical Science, St. Michael's Hospital, University of Toronto, Toronto, Ontario, Canada
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Abstract
PURPOSE OF REVIEW Heterozygous familial hypercholesterolemia often went unrecognized in China when population cholesterol levels were low, but rapid economic development has changed the situation. This review will discuss the current position of awareness, diagnosis, and management of familial hypercholesterolemia in Chinese populations. RECENT FINDINGS The phenotype of familial hypercholesterolemia in China and other Chinese populations has become similar to that in Western countries, although it may still be somewhat less severe. The prevalence in Chinese populations is also similar to that in other countries and it has been found in up to 7% of Chinese patients with premature coronary heart disease. Most of the mutations are in the low-density lipoprotein receptor gene but the pattern of mutations differs from that in Whites. Chinese patients may be more responsive to statins than Whites but patients with familial hypercholesterolemia are often undertreated. SUMMARY Increasing population cholesterol levels have changed the phenotype of familial hypercholesterolemia in China and Chinese patients now resemble those in Western countries. International initiatives are facilitating increased awareness and identification of cases and more effective management of the condition.
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Affiliation(s)
- Brian Tomlinson
- Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Hong Kong
| | - Miao Hu
- Bright Future Pharmaceutical Laboratories Limited, Hong Kong
| | - Elaine Chow
- Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Hong Kong
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Cheng X, Huang Y, Qiu X, Cheng X, Jin Y, Hu Y, Yang B, Zhao J, Lei Y, Zheng F. Novel compound heterozygous mutations in low density lipoprotein receptor gene causes a severe phenotype in a Chinese hypercholesterolemia family. Exp Ther Med 2018; 16:901-907. [PMID: 30112042 DOI: 10.3892/etm.2018.6205] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Accepted: 02/07/2017] [Indexed: 11/05/2022] Open
Abstract
Mutations in the low density lipoprotein receptor (LDLR) gene serve a causative role in the pathophysiology of familial hypercholesterolemia (FH), a common autosomal inherited disorder characterized by abnormal lipid metabolism. The aim of the present study was to investigate genetic defects in a Chinese family with FH. Clinical features and family histories were collected, as were the results of various laboratory tests, including determinations of serum lipid concentrations, ultrasonography and angiography results. Potential mutations in LDLR were screened using direct polymerase chain reaction (PCR) sequencing. Multiple sequence alignments, structure and hydrophobicity predictions were performed in silico. Novel compound heterozygote mutations in LDLR of the proband were identified, with a Trp577Term-bearing maternal allele and a Pro685Leu-bearing paternal allele. The proband, a 27-year-old male, had severe and diffuse coronary stenosis and non-ST segment elevation myocardial infarction, as well as multiple skin xanthomas and high serum lipid levels. The allele-dosage-dependent clinical features, including hypercholesterolemia and peripheral arterial atherosclerosis, were observed in the proband and the other heterozygous patients. Therefore, the coexistence of Pro685Leu and Trp577Term mutations in LDLR is a novel compound heterozygosis in Chinese patients and may lead to a severe FH phenotype. The explanation for the existence of compound heterozygous mutations instead of homozygous mutations in this particular family requires further study.
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Affiliation(s)
- Xinyao Cheng
- Cardiovascular Division, Zhongnan Hospital, Wuhan University, Wuhan, Hubei 430071, P.R. China
| | - Yifang Huang
- Center for Gene Diagnosis, Zhongnan Hospital, Wuhan University, Wuhan, Hubei 430071, P.R. China
| | - Xueping Qiu
- Center for Gene Diagnosis, Zhongnan Hospital, Wuhan University, Wuhan, Hubei 430071, P.R. China
| | - Xiaohuan Cheng
- Center for Gene Diagnosis, Zhongnan Hospital, Wuhan University, Wuhan, Hubei 430071, P.R. China
| | - Yalei Jin
- Geriatrics Division, Zhongnan Hospital, Wuhan University, Wuhan, Hubei 430071, P.R. China
| | - Yafei Hu
- Ultrasonography Division, Enshi Center Hospital, Enshi, Hubei 445000, P.R. China
| | - Bing Yang
- Ultrasonography Division, Enshi Center Hospital, Enshi, Hubei 445000, P.R. China
| | - Jingbo Zhao
- Ultrasonography Division, Enshi Center Hospital, Enshi, Hubei 445000, P.R. China
| | - Yuhua Lei
- Ultrasonography Division, Enshi Center Hospital, Enshi, Hubei 445000, P.R. China
| | - Fang Zheng
- Center for Gene Diagnosis, Zhongnan Hospital, Wuhan University, Wuhan, Hubei 430071, P.R. China
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10
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Validation of LDLr Activity as a Tool to Improve Genetic Diagnosis of Familial Hypercholesterolemia: A Retrospective on Functional Characterization of LDLr Variants. Int J Mol Sci 2018; 19:ijms19061676. [PMID: 29874871 PMCID: PMC6032215 DOI: 10.3390/ijms19061676] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2018] [Revised: 05/28/2018] [Accepted: 06/04/2018] [Indexed: 12/11/2022] Open
Abstract
Familial hypercholesterolemia (FH) is an autosomal dominant disorder characterized by high blood-cholesterol levels mostly caused by mutations in the low-density lipoprotein receptor (LDLr). With a prevalence as high as 1/200 in some populations, genetic screening for pathogenic LDLr mutations is a cost-effective approach in families classified as ‘definite’ or ‘probable’ FH and can help to early diagnosis. However, with over 2000 LDLr variants identified, distinguishing pathogenic mutations from benign mutations is a long-standing challenge in the field. In 1998, the World Health Organization (WHO) highlighted the importance of improving the diagnosis and prognosis of FH patients thus, identifying LDLr pathogenic variants is a longstanding challenge to provide an accurate genetic diagnosis and personalized treatments. In recent years, accessible methodologies have been developed to assess LDLr activity in vitro, providing experimental reproducibility between laboratories all over the world that ensures rigorous analysis of all functional studies. In this review we present a broad spectrum of functionally characterized missense LDLr variants identified in patients with FH, which is mandatory for a definite diagnosis of FH.
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11
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Ma Y, Gong Y, Garg A, Zhou H. Compound heterozygous familial hypercholesterolemia in a Chinese boy with a de novo and transmitted low-density lipoprotein receptor mutation. J Clin Lipidol 2018; 12:230-235.e6. [DOI: 10.1016/j.jacl.2017.10.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Revised: 09/19/2017] [Accepted: 10/10/2017] [Indexed: 01/23/2023]
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Bourbon M, Alves AC, Sijbrands EJ. Low-density lipoprotein receptor mutational analysis in diagnosis of familial hypercholesterolemia. Curr Opin Lipidol 2017; 28:120-129. [PMID: 28169869 DOI: 10.1097/mol.0000000000000404] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
PURPOSE OF REVIEW To present up to date evidence on the pathogenicity of low-density lipoprotein receptor (LDLR) variants and to propose a strategy that is suitable for implementation in the clinical work-up of familial hypercholesterolaemia. RECENT FINDINGS More than 1800 variants have been described in the LDLR gene of patients with a clinical diagnosis of familial hypercholesterolaemia; however, less than 15% have functional evidence of pathogenicity. SUMMARY The spectrum of variants in the LDLR identified in patients with clinical familial hypercholesterolaemia is increasing as novel variants are still being reported. However, over 50% of all LDLR variants need further evidence before they can be confirmed as mutations causing disease. Even with applying the recent American College of Medical Genetics variant classification, a large number of variants are still considered variants of unknown significance. Before obtaining an undisputable confirmation of the effect on the expression and activity of the LDLR, reporting these variants as part of a clinical diagnosis to the patient holds the risk that it might need to be withdrawn in a later stage. An investment should be made to develop functional assays to characterize LDLR variants of unknown significance for a better patient diagnosis and to prevent confusion in the physician's office.
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Affiliation(s)
- Mafalda Bourbon
- aUnidade de I&D, Grupo de Investigação Cardiovascular, Departamento de Promoção da Saúde e Prevenção de Doenças Não Transmissíveis, Instituto Nacional de Saúde Doutor Ricardo Jorge bBioISI - Biosystems & Integrative Sciences Institute, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal cDepartment of internal Medicine, Erasmus University Rotterdam, Rotterdam, the Netherlands
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Widhalm K, Benke IM, Fritz M, Geiger H, Helk O, Fritsch M, Hoermann G, Kostner G. Homozygous familial hypercholesterolemia: Summarized case reports. Atherosclerosis 2017; 257:86-89. [PMID: 28126585 DOI: 10.1016/j.atherosclerosis.2017.01.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Revised: 11/28/2016] [Accepted: 01/11/2017] [Indexed: 01/24/2023]
Abstract
BACKGROUND AND AIMS Homozygous familial hypercholesterolemia (hoFH) is a rare genetic disorder with potential severe atherosclerosis in the pediatric age. METHODS We report on 9 patients with hoFH, who had been diagnosed within the last 30 years and who were consequently treated with apheresis and drugs. RESULTS Two deaths occurred: one at age 36 years and the other at age four and a half years before effective treatment was commenced. All other patients are still in good clinical condition today, although four of them have proven aortic stenosis or arterial plaques. CONCLUSIONS Our case report highlights that adequate treatment should start as early as possible to delay the onset of clinical manifestations of atherosclerosis. It can be assumed that the introduction of new drugs can improve the outcome and possibly lengthen the life expectancy of patients affected by hoFH.
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Affiliation(s)
- Kurt Widhalm
- Department of Pediatrics and Adolescent Medicine, Medical University of Vienna, Austria.
| | - Ina Michel Benke
- Department of Pediatrics and Adolescent Medicine, Medical University of Vienna, Austria
| | - Michael Fritz
- Hospital Feldkirch, Department of Pediatrics, Austria
| | | | - Oliver Helk
- Institute for Medical Sciences, University of Aberdeen, UK
| | - Maria Fritsch
- Department of Pediatrics and Adolescent Medicine, Medical University of Vienna, Austria
| | - Gregor Hoermann
- Department of Laboratory Medicine, Medical University of Vienna, Austria
| | - Gerhard Kostner
- Department of Biochemistry, Medical University of Graz, Austria
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Leigh S, Futema M, Whittall R, Taylor-Beadling A, Williams M, den Dunnen JT, Humphries SE. The UCL low-density lipoprotein receptor gene variant database: pathogenicity update. J Med Genet 2016; 54:217-223. [PMID: 27821657 PMCID: PMC5502305 DOI: 10.1136/jmedgenet-2016-104054] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Accepted: 10/06/2016] [Indexed: 12/04/2022]
Abstract
Background Familial hypercholesterolaemia (OMIM 143890) is most frequently caused by variations in the low-density lipoprotein receptor (LDLR) gene. Predicting whether novel variants are pathogenic may not be straightforward, especially for missense and synonymous variants. In 2013, the Association of Clinical Genetic Scientists published guidelines for the classification of variants, with categories 1 and 2 representing clearly not or unlikely pathogenic, respectively, 3 representing variants of unknown significance (VUS), and 4 and 5 representing likely to be or clearly pathogenic, respectively. Here, we update the University College London (UCL) LDLR variant database according to these guidelines. Methods PubMed searches and alerts were used to identify novel LDLR variants for inclusion in the database. Standard in silico tools were used to predict potential pathogenicity. Variants were designated as class 4/5 only when the predictions from the different programs were concordant and as class 3 when predictions were discordant. Results The updated database (http://www.lovd.nl/LDLR) now includes 2925 curated variants, representing 1707 independent events. All 129 nonsense variants, 337 small frame-shifting and 117/118 large rearrangements were classified as 4 or 5. Of the 795 missense variants, 115 were in classes 1 and 2, 605 in class 4 and 75 in class 3. 111/181 intronic variants, 4/34 synonymous variants and 14/37 promoter variants were assigned to classes 4 or 5. Overall, 112 (7%) of reported variants were class 3. Conclusions This study updates the LDLR variant database and identifies a number of reported VUS where additional family and in vitro studies will be required to confirm or refute their pathogenicity.
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Affiliation(s)
- Sarah Leigh
- Centre for Cardiovascular Genetics, Institute of Cardiovascular Sciences, University College London, London, UK
| | - Marta Futema
- Centre for Cardiovascular Genetics, Institute of Cardiovascular Sciences, University College London, London, UK
| | - Ros Whittall
- Centre for Cardiovascular Genetics, Institute of Cardiovascular Sciences, University College London, London, UK
| | | | - Maggie Williams
- Bristol Genetics Laboratory, Pathology Sciences, Blood Sciences and Bristol Genetics, Southmead Hospital, Bristol, UK
| | - Johan T den Dunnen
- Clinical Genetics and Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Steve E Humphries
- Centre for Cardiovascular Genetics, Institute of Cardiovascular Sciences, University College London, London, UK
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Setia N, Saxena R, Arora A, Verma IC. Spectrum of mutations in homozygous familial hypercholesterolemia in India, with four novel mutations. Atherosclerosis 2016; 255:31-36. [PMID: 27816806 DOI: 10.1016/j.atherosclerosis.2016.10.028] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Revised: 10/10/2016] [Accepted: 10/13/2016] [Indexed: 11/30/2022]
Abstract
BACKGROUND AND AIMS Homozygous familial hypercholesterolemia (FH) is a rare but serious, inherited disorder of lipid metabolism characterized by very high total and LDL cholesterol levels from birth. It presents as cutaneous and tendon xanthomas since childhood, with or without cardiac involvement. FH is commonly caused by mutations in three genes, i.e. LDL receptor (LDLR), apolipoprotein B (ApoB) and PCSK9. We aimed to determine the spectrum of mutations in cases of homozygous FH in Asian Indians and evaluate if there was any similarity to the mutations observed in Caucasians. METHODS Sixteen homozygous FH subjects from eleven families were analyzed for mutations by Sanger sequencing. Large rearrangements in LDLR gene were evaluated by multiplex ligation probe dependent amplification (MLPA) technique. RESULTS Ten mutations were observed in LDLR gene, of which four mutations were novel. No mutation was detected in ApoB gene and common PCSK9 mutation (p.D374Y). Fourteen cases had homozygous mutations; one had compound heterozygous mutation, while no mutation was detected in one clinically homozygous case. We report an interesting "Triple hit" case with features of homozygous FH. CONCLUSIONS The spectrum of mutations in the Asian Indian population is quite heterogeneous. Of the mutations identified, 40% were novel. No mutation was observed in exons 3, 9 and 14 of LDLR gene, which are considered to be hot spots in studies done on Asian Indians in South Africa. Early detection followed by aggressive therapy, and cascade screening of extended families has been initiated to reduce the morbidity and mortality in these patients.
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Affiliation(s)
- Nitika Setia
- Institute of Medical Genetics and Genomics, Sir Ganga Ram Hospital, New Delhi, 110060, India.
| | - Renu Saxena
- Institute of Medical Genetics and Genomics, Sir Ganga Ram Hospital, New Delhi, 110060, India
| | - Anjali Arora
- Hyperlipidemia Prevention Clinic, Department of Cardiology, Sir Ganga Ram Hospital, New Delhi, 110060, India
| | - Ishwar C Verma
- Institute of Medical Genetics and Genomics, Sir Ganga Ram Hospital, New Delhi, 110060, India
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16
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Genetic diagnosis of familial hypercholesterolemia in Han Chinese. J Clin Lipidol 2016; 10:490-6. [DOI: 10.1016/j.jacl.2016.01.009] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2015] [Revised: 01/22/2016] [Accepted: 01/26/2016] [Indexed: 12/26/2022]
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Hu M, Hooper AJ, Bockxmeer FMV, Watts GF, Chan JCN, Tomlinson B. Management of Familial Hypercholesterolemia in Hong Kong. J Atheroscler Thromb 2016; 23:520-31. [DOI: 10.5551/jat.34314] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Affiliation(s)
- Miao Hu
- Department of Medicine and Therapeutics, The Chinese University of Hong Kong
| | - Amanda J Hooper
- Department of Core Clinical Pathology & Biochemistry, Royal Perth Hospital; School of Medicine and Pharmacology, University of Western Australia; School of Pathology & Laboratory Medicine, University of Western Australia
| | | | - Gerald F Watts
- School of Medicine and Pharmacology, University of Western Australia; Lipid Disorders Clinic, Department of Cardiology, Royal Perth Hospital
| | - Juliana CN Chan
- Department of Medicine and Therapeutics, The Chinese University of Hong Kong
| | - Brian Tomlinson
- Department of Medicine and Therapeutics, The Chinese University of Hong Kong
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The distribution and characteristics of LDL receptor mutations in China: A systematic review. Sci Rep 2015; 5:17272. [PMID: 26608663 PMCID: PMC4660303 DOI: 10.1038/srep17272] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Accepted: 10/28/2015] [Indexed: 01/05/2023] Open
Abstract
Familial hypercholesterolemia (FH) is a common and serious dominant genetic disease, and its main pathogenic gene is the low-density lipoprotein receptor (LDLR) gene. This study aimed to perform a systematic review of LDLR mutations in China. Using PubMed, Embase, Wanfang (Chinese), the Chinese National Knowledge Infrastructure (Chinese), and the Chinese Biological and Medical database (Chinese), public data were limited to December 2014. The Medical Subject Headings terms and the following key words were used: “familial hypercholesterolemia”, “Chinese”, “China”, “Hong Kong”, and “Taiwan”. A total of 74 studies including 295 probands with 131 LDLR mutations were identified. Most of the mutations were located in exon 4 of LDLR and approximately 60% of the mutations were missense mutations. Thirty new mutations that were not recorded in the LDLR databases were found. In silico analysis revealed that most of the mutations were pathogenic. The primary LDLR mutations were C308Y, H562Y, and A606T, and all of the mutations had functional significance. Prevalence data suggest that there are nearly 3.8 million FH patients in China, although reported numbers are much smaller, suggesting that FH is widely misunderstood. This systematic review provides information that is specific to China for inclusion in the international FH database.
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Novel mutations of low-density lipoprotein receptor gene in China patients with familial hypercholesterolemia. Appl Biochem Biotechnol 2015; 176:101-9. [PMID: 25846081 DOI: 10.1007/s12010-015-1554-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Accepted: 02/22/2015] [Indexed: 12/30/2022]
Abstract
Familial hypercholesterolaemia (FH) is an autosomal dominant genetic disorder, associated with elevated level of serum low-density lipoprotein-cholesterol (LDL-C), which can lead to premature cardiovascular disease (CVD). Mutations in low density lipoprotein receptor (LDLR) and proprotein convertase subtilisin/kexin type 9 (PCSK9) have been identified to be the underlying cause of this disease. Genetic research of FH has already been extensively studied all over the world. However, reports of FH mutations in the Chinese population are still limited. In this paper, 20 unrelated FH families were enrolled to detect the candidate gene variants in Chinese FH population by DNA direct sequencing. We identified 12 LDLR variants in 13 FH probands. Importantly, we first reported two unique mutations (c.2000_2000 delG/p.C667LfsX6 and c.605T>C/p.F202S) in LDLR gene. Our discoveries expand the spectrum of LDLR mutations and contribute to the genetic diagnosis and counseling for FH patients.
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20
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Komarova TY, Korneva VA, Kuznetsova TY, Golovina AS, Vasilyev VB, Mandelshtam MY. Familial hypercholesterolemia mutations in Petrozavodsk: no similarity to St. Petersburg mutation spectrum. BMC MEDICAL GENETICS 2013; 14:128. [PMID: 24373485 PMCID: PMC3877960 DOI: 10.1186/1471-2350-14-128] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Accepted: 12/19/2013] [Indexed: 01/26/2023]
Abstract
Background Familial hypercholesterolemia (FH) is a human monogenic disease induced by a variety of mutations with striking genetic diversity. Despite this variability recurrent mutations occur in each population studied, which allows both elucidating prevalent mutations and developing DNA diagnostic tools for the disease. Recent research of FH in St. Petersburg, Moscow and Novosibirsk (major cities in Russia) demonstrates that each megapolis has its own FH mutation spectrum sharing only small part of mutations with other populations in Russia and Europe. In order to optimize molecular-genetic diagnostic protocols for FH in Russia we studied mutation spectrum in other regions including Petrozavodsk, a smaller town in relatively close proximity to St. Petersburg. Methods The principal method was automated detection of single-strand conformation polymorphism followed by direct PCR amplified DNA sequencing. Results Twelve different mutations of the low density lipoprotein (LDL) receptor gene were detected in the Petrozavodsk sample (80 patients). Out of these twelve mutations, seven have never been described before (c.192_201delinsGGACTTCA, c. 195_196insT, c. 618 T > G, c. 1340C > G, c. 1686_1693delinsT, c. 1936C > A, c. 2191delG). Other five mutations (c. 58G > A, c. 925_931del, c. 1194C > T, c. 1532 T > C, c. 1920C > T) were previously characterized elsewhere. All new mutations are considered to be a probable cause of the FH in their carriers. Direct evidence of the neutral character of c.58G > A or p. (Gly20Arg) is provided for the first time. Each pathogenic mutation was a trait of its own unique pedigree and so far has not been found in other patients. Conclusions Strikingly, out of twelve mutations characterized in the Petrozavodsk sample only one mutation, c. 925_931del, has previously been found in patients from St. Petersburg and Finland (most closely located studied populations), suggesting some common roots in origin of these populations in the past or limited gene exchange between them nowadays. No recurrent mutations were detected.
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Affiliation(s)
| | | | | | | | | | - Michail Yu Mandelshtam
- Department of Molecular Genetics, Institute for Experimental Medicine, NW Branch of Russian Academy of Medical Sciences, Pavlov Street, 12, St,Petersburg 197376, Russia.
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Heterozygous familial hypercholesterolemia in Hong Kong Chinese. Study of 252 cases. Int J Cardiol 2013; 167:762-7. [DOI: 10.1016/j.ijcard.2012.03.048] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/16/2012] [Accepted: 03/03/2012] [Indexed: 01/30/2023]
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22
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Chiou KR, Charng MJ. Common mutations of familial hypercholesterolemia patients in Taiwan: Characteristics and implications of migrations from southeast China. Gene 2012; 498:100-6. [DOI: 10.1016/j.gene.2012.01.092] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2011] [Accepted: 01/29/2012] [Indexed: 10/14/2022]
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23
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Waluś-Miarka M, Sanak M, Idzior-Waluś B, Miarka P, Witek P, Małecki MT, Czarnecka D. A novel mutation (Cys308Phe) of the LDL receptor gene in families from the South-Eastern part of Poland. Mol Biol Rep 2011; 39:5181-6. [PMID: 22160468 PMCID: PMC3310989 DOI: 10.1007/s11033-011-1314-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2011] [Accepted: 11/30/2011] [Indexed: 11/30/2022]
Abstract
The purpose of this investigation was to characterize a new mutation in the LDL-receptor (LDLR) gene in three families with clinically diagnosed familial hypercholesterolemia (FH) from the South-Eastern part of Poland. Mutational screening with exon by exon sequencing analysis was performed in all probands. The novel mutation c986G>T (Cys308Phe) in the exon 7 of LDLR gene was found in three apparently unrelated probands with FH. Analysis of the receptor activity of peripheral blood lymphocytes by binding and uptake of DiL-LDL showed a significant reduction (by 24% versus healthy control) of the fluorescent label in the lymphocytes of patients heterozygous for this mutation. Concentrations of serum LDL-C in probands before treatment were between 9.5 and 10.5 mmol/l. All patients had corneal arcus and tendon xanthoma. Clinically, families were characterized by premature coronary artery disease. This mutation occurred relatively frequently in our group of patients with FH, but this could be explained by a founder effect since we demonstrated their common ancestors.
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Affiliation(s)
- Małgorzata Waluś-Miarka
- Department of Metabolic Diseases, Jagiellonian University, Medical School, Kopernika 15, 31-501, Kraków, Poland.
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Shawar SM, Al-Drees MA, Ramadan AR, Ali NH, Alfadhli SM. The Arabic allele: a single base pair substitution activates a 10-base downstream cryptic splice acceptor site in exon 12 of LDLR and severely decreases LDLR expression in two unrelated Arab families with familial hypercholesterolemia. Atherosclerosis 2011; 220:429-36. [PMID: 22129472 DOI: 10.1016/j.atherosclerosis.2011.10.045] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2011] [Revised: 10/14/2011] [Accepted: 10/30/2011] [Indexed: 10/15/2022]
Abstract
Familial hypercholesterolemia (FH) is a monogenic autosomal dominant disorder caused by defects in LDLR. Few reports describe FH mutations among Arabs. We describe a mutation in LDLR of two unrelated Arab families. We investigated 19 patients using DNA sequencing, RFLP, and real-time (RT) PCR. DNA sequencing showed a base pair substitution (c.1706-2 A>T) in the splice acceptor site of LDLR intron 11. Our results were confirmed by RFLP on 2% agarose gel. In silico analysis predicted a new cryptic splice site downstream of the original position generating a 10-base deletion from the beginning of exon 12; (c.1706-1715del.ATCTCCTCAG). cDNA sequencing of exon 12 confirmed the computational analysis. The deletion was visualized on 4% agarose gel. The deletion generates a frameshift and a premature termination codon (c.1991-1993; p.(Asp569Valfs*93). RT-PCR revealed that LDLR mRNA is 9.3%±6.5 and 17.9%±8.0 for FH homozygote and heterozygote individuals respectively, compared to a healthy family control. We predict a class II LDLR mutation that leads to a truncated receptor missing exons 14-18. We called this mutation "the Arabic allele". We expect a significant contribution of this mutation to the prevalence of FH among Arabs. Also, we propose that the severe down regulation of LDLR mRNA expression is due to nonsense-mediated-decay.
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Affiliation(s)
- Said M Shawar
- Biotechnology Program, Arabian Gulf University, Manama, Bahrain.
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An APEX-based genotyping microarray for the screening of 168 mutations associated with familial hypercholesterolemia. Atherosclerosis 2011; 216:139-45. [DOI: 10.1016/j.atherosclerosis.2011.01.023] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2010] [Revised: 01/03/2011] [Accepted: 01/10/2011] [Indexed: 12/20/2022]
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Hu M, Mak VWL, Tomlinson B. Simvastatin-induced myopathy, the role of interaction with diltiazem and genetic predisposition. J Clin Pharm Ther 2010; 36:419-25. [DOI: 10.1111/j.1365-2710.2010.01184.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Hopkins PN. Encouraging appropriate treatment for familial hypercholesterolemia. ACTA ACUST UNITED AC 2010. [DOI: 10.2217/clp.10.22] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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28
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Tomlinson B, Hu M, Lee VWY, Lui SSH, Chu TTW, Poon EWM, Ko GTC, Baum L, Tam LS, Li EK. ABCG2 polymorphism is associated with the low-density lipoprotein cholesterol response to rosuvastatin. Clin Pharmacol Ther 2010; 87:558-62. [PMID: 20130569 DOI: 10.1038/clpt.2009.232] [Citation(s) in RCA: 106] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The ATP-binding cassette G2 (ABCG2) c.421C>A (rs2231142) polymorphism influences the pharmacokinetics of rosuvastatin. We examined whether this polymorphism influences the low-density lipoprotein cholesterol (LDL-C)-lowering efficacy of the drug. In 305 Chinese patients with hypercholesterolemia who were treated with rosuvastatin at a dosage of 10 mg daily, the c.421A variant was found to be significantly associated with greater reduction in LDL-C level, in a gene-dose-dependent manner. As compared with subjects with the c.421CC genotype, those with the c.421AA genotype showed a 6.9% greater reduction in LDL-C level, which would be equivalent to the effect obtained by doubling the dose of rosuvastatin.
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Affiliation(s)
- B Tomlinson
- Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong.
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Guardamagna O, Restagno G, Rolfo E, Pederiva C, Martini S, Abello F, Baracco V, Pisciotta L, Pino E, Calandra S, Bertolini S. The type of LDLR gene mutation predicts cardiovascular risk in children with familial hypercholesterolemia. J Pediatr 2009; 155:199-204.e2. [PMID: 19446849 DOI: 10.1016/j.jpeds.2009.02.022] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2008] [Revised: 01/09/2009] [Accepted: 02/09/2009] [Indexed: 11/28/2022]
Abstract
OBJECTIVE To ascertain whether the molecular characterization of a defect in the low-density lipoprotein (LDL) receptor gene (LDLR) in children with heterozygous familial hypercholesterolemia (heFH) identifies subjects at greater risk of developing premature coronary artery disease (pCAD) later in life. STUDY DESIGN We investigated 264 children with heFH from 201 families, along with 148 affected parents and 100 unaffected siblings. The lipid profile was assessed before any treatment was provided, and genotype analysis was performed to characterize LDLR defects. In a subgroup of children with heFH and controls, we measured aorta and carotid intima-media thickness (aIMT and cIMT). The prevalence of pCAD in parents and/or grandparents with heFH was recorded. RESULTS The children with heFH with a family history of pCAD had higher LDL cholesterol and apolipoprotein B levels and greater aIMT and cIMT than those with negative family history. Compared with carriers of LDLR-defective mutations, carriers of LDLR-negative mutations had a more severe phenotype, in terms of plasma lipid levels and IMT, and a higher prevalence of pCAD in first-degree relatives (36% vs 6.7%; P < .001). CONCLUSIONS The study of heFH in children, in which other risk factors for CAD play a minor role, allows early identification of those at increased risk for developing pCAD, who merit more stringent clinical control and early pharmacologic treatment.
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Su P, Wang L, Lin J, Liu S, Xia J, Xu Y, Yong Q, Yang Y, Pan X, Du L, Qin Y, Wu Z. A novel mutation of the LDL receptor gene leading to familial hypercholesterolemia. EUR J LIPID SCI TECH 2009. [DOI: 10.1002/ejlt.200800196] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Pengyu Su
- Department of Atherosclerosis, Beijing Institute of Heart Lung and Blood Vessel Diseases, Beijing Anzhen Hospital, Capital Medical University, Beijing, China
| | - Luya Wang
- Department of Atherosclerosis, Beijing Institute of Heart Lung and Blood Vessel Diseases, Beijing Anzhen Hospital, Capital Medical University, Beijing, China
| | - Jie Lin
- Department of Atherosclerosis, Beijing Institute of Heart Lung and Blood Vessel Diseases, Beijing Anzhen Hospital, Capital Medical University, Beijing, China
| | - Shu Liu
- Department of Atherosclerosis, Beijing Institute of Heart Lung and Blood Vessel Diseases, Beijing Anzhen Hospital, Capital Medical University, Beijing, China
| | - Junhui Xia
- Department of Atherosclerosis, Beijing Institute of Heart Lung and Blood Vessel Diseases, Beijing Anzhen Hospital, Capital Medical University, Beijing, China
| | - Yingjie Xu
- Department of Atherosclerosis, Beijing Institute of Heart Lung and Blood Vessel Diseases, Beijing Anzhen Hospital, Capital Medical University, Beijing, China
| | - Qiang Yong
- Department of Atherosclerosis, Beijing Institute of Heart Lung and Blood Vessel Diseases, Beijing Anzhen Hospital, Capital Medical University, Beijing, China
| | - Ya Yang
- Department of Atherosclerosis, Beijing Institute of Heart Lung and Blood Vessel Diseases, Beijing Anzhen Hospital, Capital Medical University, Beijing, China
| | - Xiaodong Pan
- Department of Atherosclerosis, Beijing Institute of Heart Lung and Blood Vessel Diseases, Beijing Anzhen Hospital, Capital Medical University, Beijing, China
| | - Lanping Du
- Department of Atherosclerosis, Beijing Institute of Heart Lung and Blood Vessel Diseases, Beijing Anzhen Hospital, Capital Medical University, Beijing, China
| | - Yanwen Qin
- Department of Atherosclerosis, Beijing Institute of Heart Lung and Blood Vessel Diseases, Beijing Anzhen Hospital, Capital Medical University, Beijing, China
| | - Zhaosu Wu
- Department of Atherosclerosis, Beijing Institute of Heart Lung and Blood Vessel Diseases, Beijing Anzhen Hospital, Capital Medical University, Beijing, China
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Wang L, Lin J, Liu S, Cao S, Liu J, Yong Q, Yang Y, Wu B, Pan X, Du L, Wu C, Qin Y, Chen B. Mutations in the LDL receptor gene in four Chinese homozygous familial hypercholesterolemia phenotype patients. Nutr Metab Cardiovasc Dis 2009; 19:391-400. [PMID: 19073363 DOI: 10.1016/j.numecd.2008.07.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2008] [Revised: 07/13/2008] [Accepted: 07/14/2008] [Indexed: 11/30/2022]
Abstract
BACKGROUND AND AIMS Familial hypercholesterolemia (FH) is an autosomal dominant disorder of lipoprotein metabolism caused by mutations in the low-density lipoprotein receptor (LDL-R) gene, leading to elevated levels of cholesterol and an increased risk of coronary heart disease. In this article, from four homozygous FH phenotype probands we identified disease causing mutations and analyzed the relationship between genotype and phenotype. METHODS AND RESULTS DNA sequencing identified five LDL-R point mutations in four unrelated families. We found a novel homozygous mutation (C210R), a homozygous mutation at W462X, a compound heterozygous mutation of C122Y and T383I, and a G>A intron 3 splice site homozygous mutation. The functional alteration caused by the novel C210R mutation was confirmed by FACS analysis. Four probands have high low-density lipoprotein cholesterol (LDL-C) levels, ranging from 14.65 to 27.66 mmol/L. Their heterozygous parents had relatively low levels. B-mode ultrasound supplemented by Doppler was used to examine aortic/mitral valve structural alterations and carotid intima-media thickness (ITM) in all probands. The ITM values were between 1.2 and 2.3mm, much higher than the normal value of <0.8mm. CONCLUSION Our data demonstrated that all the probands were associated with severe hypercholesterolemia, thick carotid IMT and a low CFVR (coronary flow velocity reserve) value. The novel mutation (C120Y) is a disease causing mutation.
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Affiliation(s)
- L Wang
- Department of Atherosclerosis, Beijing Institute of Heart Lung and Blood Vessel Diseases, Beijing Anzhen Hospital, Affiliated of Capital University of Medical Sciences, Beijing 100029, PR China.
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Cheng X, Ding J, Zheng F, Zhou X, Xiong C. Two mutations in LDLR gene were found in two Chinese families with familial hypercholesterolemia. Mol Biol Rep 2008; 36:2053-7. [DOI: 10.1007/s11033-008-9416-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2008] [Accepted: 10/29/2008] [Indexed: 11/30/2022]
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Functional analysis of low-density lipoprotein receptor in homozygous familial hypercholesterolemia patients with novel 1439 C→T mutation of low-density lipoprotein receptor gene. Chin Med J (Engl) 2008. [DOI: 10.1097/00029330-200805010-00002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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Rahalkar AR, Hegele RA. Monogenic pediatric dyslipidemias: classification, genetics and clinical spectrum. Mol Genet Metab 2008; 93:282-94. [PMID: 18023224 DOI: 10.1016/j.ymgme.2007.10.007] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/28/2007] [Revised: 10/09/2007] [Accepted: 10/09/2007] [Indexed: 12/20/2022]
Abstract
Monogenic disorders that cause abnormal levels of plasma cholesterol and triglycerides have received much attention due to their role in metabolic dysfunction and cardiovascular disease. While these disorders often present clinically during adulthood, some present most commonly in the pediatric population and can have serious consequences if misdiagnosed or untreated. This review provides an overview of monogenic lipid disorders that present with unusually high or low levels of plasma cholesterol and/or triglycerides during infancy, childhood and adolescence. Biochemical and genetic findings, clinical presentation and treatment options are discussed with an emphasis upon recent advances in our understanding and management of these monogenic disorders.
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Affiliation(s)
- Amit R Rahalkar
- Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ont., Canada
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Yang KC, Su YN, Shew JY, Yang KY, Tseng WK, Wu CC, Lee YT. LDLR and ApoB are major genetic causes of autosomal dominant hypercholesterolemia in a Taiwanese population. J Formos Med Assoc 2007; 106:799-807. [PMID: 17964958 DOI: 10.1016/s0929-6646(08)60044-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND/PURPOSE Autosomal dominant hypercholesterolemia (ADH) is an autosomal dominant inherited disease characterized by an increase in low-density lipoprotein cholesterol levels and premature coronary heart disease, which can be caused by mutations in genes encoding the low-density lipoprotein receptor (LDLR), apolipoprotein B (APOB) and proprotein convertase subtilisin/kexin type 9 (PCSK9). There is scant information with regard to the role played by each gene in the Taiwanese ADH population, especially the newly discovered PCSK9 gene. METHODS We used coupling heteroduplex analysis based on a denaturing high performance liquid chromatography system and DNA sequencing to screen for the LDLR gene, APOB gene and PCSK9 gene in 87 ADH cases recruited from 30 unrelated Taiwanese families. RESULTS We did not find any mutation-causing variant of the PCSK9 gene in our cases and thus excluded PCSK9 as the major culprit mutation in these families. On the other hand, we identified six previously reported LDLR gene mutations (C107Y, D69N, R385W, W462X, G170X, V408M), two novel LDLR gene mutations (FsG631 and splice junction mutation of intron 10), and one known mutation (R3500W) and one novel missense mutation (T3540M) in the APOB gene that were present in 55 members from 18 ADH families (60%). R3500W, rather than R3500Q, could be the principle mutation responsible for familial defective apolipoprotein B in Taiwanese. CONCLUSION The results of our study reveal a characteristic mutation pattern of ADH in Taiwan, mainly in the LDLR and APOB genes. However, PCSK9 gene mutation may not be a major cause of ADH in our study population.
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Affiliation(s)
- Kai-Chien Yang
- Division of Cardiology, Department of Internal Medicine, E-Da Hospital, Kaohsiung, Taiwan
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36
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Two novel mutations of the LDL receptor gene associated with familial hypercholesterolemia in a Chinese family. Chin Med J (Engl) 2007. [DOI: 10.1097/00029330-200710010-00010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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Charng MJ, Chiou KR, Chang HM, Cheng HM, Ye ZX, Lin SJ. Identification and characterization of novel low-density lipoprotein receptor mutations of familial hypercholesterolaemia patients in Taiwan. Eur J Clin Invest 2006; 36:866-74. [PMID: 17087781 DOI: 10.1111/j.1365-2362.2006.01735.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND Familial hypercholesterolaemia (FH) is an autosomal dominant disease associated with a very high risk of coronary vascular disease. The study objective was to identify patients with FH in Taiwan and characterize novel mutations. MATERIALS AND METHODS Fifty-one patients with suspected FH living in Taiwan were screened for mutations in both the low-density lipoprotein (LDL) receptor and the apolipoprotein (apoB) genes using the multiplex polymerase chain reaction and exon-by-exon DNA sequencing technique. Functional consequences on LDL receptor activity were characterized in vitro for novel mutations and family pedigree was also analyzed. RESULTS Thirteen different functional mutations in the LDL receptor gene and one mutation in the apoB gene were found in 21 patients. Among the 13 mutations in the LDL receptor gene, 10 were single-point missense mutations, one was a two-point mutation in the same allele, one was a non-sense mutation and one was a frame-shift mutation. There were three novel mutations, including two missense mutations (M510K and W512R) and one frame-shift mutation (1953 delTA mutation). The characterization of missense M510K retained 36.2% of the activity of the normal receptor. Conversely, frame-shift 1953 delTA and missense W512R led to defective proteins, with only 0-6% of normal receptor activity. CONCLUSIONS The study identified 13 LDL receptor gene mutations and characterized three novel mutations causing FH in Taiwan. This facilitated a better understanding of FH among the Chinese population and may enable diagnosis of FH at the molecular level at a presymptomatic, early age.
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Affiliation(s)
- M J Charng
- Division of Cardiology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.
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38
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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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Chang JH, Pan JP, Tai DY, Huang AC, Li PH, Ho HL, Hsieh HL, Chou SC, Lin WL, Lo E, Chang CY, Tseng J, Su MT, Lee-Chen GJ. Identification and characterization of LDL receptor gene mutations in hyperlipidemic Chinese. J Lipid Res 2003; 44:1850-8. [PMID: 12837857 DOI: 10.1194/jlr.m200470-jlr200] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
DNA screening for LDL receptor mutations was performed in 170 unrelated hyperlipidemic Chinese patients and two clinically diagnosed familial hypercholesterolemia patients. Two deletions (Del e3-5 and Del e6-8), eight point mutations (W-18X, D69N, R94H, E207K, C308Y, I402T, A410T, and A696G), and two polymorphisms (A370T and I602V) were identified. Of these mutations, C308Y and Del e6-8 were found in homozygosity, and D69N and C308Y were seen in unrelated patients. The effects of mutations on LDL receptor function were characterized in COS-7 cells. The LDL receptor level and activity were close to those of wild type in A696G transfected cells. A novel intermediate protein and reduction of LDL receptor activity were seen in D69N transfected cells. For R94H, E207K, C308Y, I402T, and A410T mutations, only approximately 20-64% of normal receptor activities were seen. Conversely, Del e3-5 and Del e6-8 lead to defective proteins with approximately 0-13% activity. Most of the mutant receptors were localized intracellularly, with a staining pattern resembling that of the endoplasmic reticulum and Golgi apparatus (D69N, R94H, E207K, C308Y, and I402T) or endosome/lysosome (A410T and Del e6-8). Molecular analysis of the LDL receptor gene will clearly identify the cause of the patient's hyperlipidemia and allow appropriate early treatment as well as antenatal and family studies.
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Affiliation(s)
- Jui-Hung Chang
- Department of Biology, National Taiwan Normal University, Taipei, Taiwan
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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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41
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Abstract
Disease genes may be identified through functional, positional, and candidate gene approaches. Although extensive and often labor-intensive studies such as family linkage analysis, functional investigation of gene products and genome database searches are usually involved, thousands of human disease genes, especially for monogenic diseases with Mendelian transmission, have been identified. However, in diseases caused by more than one gene, or by a combination of genetic and environmental factors, identification of the genes is even more difficult. Common examples include atherosclerosis, cancer, Alzheimer's disease, asthma, diabetes, glaucoma, and age-related macular degeneration. There have been conflicting reports on the roles of associated genes. Even with population-based case-control studies and new statistical methods such as the sib-ship disequilibrium test and the discordant alleles test, there is no agreement on whether alpha2-macroglobulin (A2M) is a gene for Alzheimer's disease. Another example is the inconsistent association between age-related macular degeneration and ATP-binding cassette transporter (ABCR). Ethnic variation causes further complications. In our investigation of LDL-receptor variants in familial hypercholesterolemia, and the trabecular meshwork inducible glucocorticoid response protein, or myocillin (TIGR-MYOC) mutation pattern in primary open angle glaucoma, we did find dissimilar results in Chinese compared to Caucasians. New information from the Human Genome Project and advancements in technologies will aid the search for and confirm identification of disease genes despite such challenges.
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Affiliation(s)
- C P Pang
- Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, China.
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Shin JA, Kim SH, Kim UK, Chae JJ, Choe SJ, Namkoong Y, Kim HS, Park YB, Lee CC. Identification of four novel mutations of the low-density lipoprotein receptor gene in Korean patients with familial hypercholesterolemia. Clin Genet 2000; 57:225-9. [PMID: 10782930 DOI: 10.1034/j.1399-0004.2000.570309.x] [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: 11/23/2022]
Abstract
To obtain insight into the genetic variation of the low-density lipoprotein (LDL) receptor gene in Korean patients with familial hypercholesterolemia (FH), we used single-strand conformation polymorphism to screen all 18 exons and a promotor of the LDL receptor gene in 20 unrelated Korean FH patients. Four novel point mutations were detected in 5 FH patients and were characterized by sequence analysis. Of them, one is a nonsense mutation, a Glu-->Stop (CAG-->TAG) at codon 161, and results in a large deletion. The other three, which were a Ala-->Glu (GCG-->GAG) mutation at signal peptide, Cys-->Tyr (TGC-->TAC) at codon 210, and Pro-->Leu (CTG-->CCG) at codon 584, were novel missense mutations, which modified the highly conserved region of the LDL receptor gene. All these mutations were absent in normolipidemic controls and were associated in heterozygote carriers with clinical signs of FH. Identification of these novel mutations provides another example of the molecular heterogeneity of the LDL receptor gene mutations causing FH.
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Affiliation(s)
- J A Shin
- Department of Molecular Biology, Seoul National University, Korea
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Bourbon M, Fowler AM, Sun XM, Soutar AK. Inheritance of two different alleles of the low-density lipoprotein (LDL)-receptor gene carrying the recurrent Pro664Leu mutation in a patient with homozygous familial hypercholesterolaemia. Clin Genet 1999; 56:225-31. [PMID: 10563483 DOI: 10.1034/j.1399-0004.1999.560308.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
Familial hypercholesterolaemia (FH) is caused by mutations in the low-density lipoprotein (LDL)-receptor gene that result in impaired clearance of plasma LDL and increased risk of coronary heart disease. Numerous different mutations have been found in FH patients worldwide, the majority of which are infrequent in out-bred populations and account for 2% or less of patients with the disorder in large cohorts. Thus, it was surprising to find that two homozygous FH patients referred to a single hospital in the UK were both apparently homozygous for the Pro664Leu mutation. One, an Asian patient, was a true homozygote. The other, of English origin, had inherited two different alleles of the LDL-receptor gene with the same mutation from unrelated parents, as inferred from the haplotype of polymorphic markers. A third, clinically homozygous FH patient, despite being the offspring of first cousins, had inherited one 'Asian' Pro664Leu allele, but an allele with a 1-bp deletion in exon 5 from the other parent. The Pro664Leu mutation in the LDL-receptor gene has now been described in heterozygous patients of very different ethnic origin and is associated with different haplotypes, suggesting that the same base change at a CpG may have recurred as many as six times.
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Affiliation(s)
- M Bourbon
- Lipoprotein Group, MRC Clinical Sciences Centre, Hammersmith Hospital, London, UK
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