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Jawabri AA, John A, Ghattas MA, Mahgoub RE, Hamad MIK, Barakat MT, Shobi B, Daggag H, Ali BR. Cellular and functional evaluation of LDLR missense variants reported in hypercholesterolemic patients demonstrates their hypomorphic impacts on trafficking and LDL internalization. Front Cell Dev Biol 2024; 12:1412236. [PMID: 39114568 PMCID: PMC11303217 DOI: 10.3389/fcell.2024.1412236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2024] [Accepted: 06/10/2024] [Indexed: 08/10/2024] Open
Abstract
Background Familial hypercholesterolemia (FH) is an autosomal dominant disorder characterized by increased LDL-cholesterol levels. About 85% of FH cases are caused by LDLR mutations encoding the low-density lipoprotein receptor (LDLR). LDLR is synthesized in the endoplasmic reticulum (ER) where it undergoes post-translational modifications and then transported through Golgi apparatus to the plasma membrane. Over 2900 LDLR variants have been reported in FH patients with limited information on the pathogenicity and functionality of many of them. This study aims to elucidate the cellular trafficking and functional implications of LDLR missense variants identified in suspected FH patients using biochemical and functional methods. Methods We used HeLa, HEK293T, and LDLR-deficient-CHO-ldlA7 cells to evaluate the subcellular localization and LDL internalization of ten LDLR missense variants (p.C167F, p.D178N, p.C243Y, p.E277K, p.G314R, p.H327Y, p.D477N, p.D622G, p.R744Q, and p.R814Q) reported in multiethnic suspected FH patients. We also analyzed the functional impact of three variants (p.D445E, p.D482H, and p.C677F), two of which previously shown to be retained in the ER. Results We show that p.D622G, p.D482H, and p.C667F are largely retained in the ER whereas p.R744Q is partially retained. The other variants were predominantly localized to the plasma membrane. LDL internalization assays in CHO-ldlA7 cells indicate that p.D482H, p.C243Y, p.D622G, and p.C667F have quantitatively lost their ability to internalize Dil-LDL with the others (p.C167F, p.D178N, p.G314R, p.H327Y, p.D445E, p.D477N, p.R744Q and p.R814Q) showing significant losses except for p.E277K which retained full activity. However, the LDL internalization assay is only to able evaluate the impact of the variants on LDL internalization and not the exact functional defects such as failure to bind LDL. The data represented illustrate the hypomorphism nature of variants causing FH which may explain some of the variable expressivity of FH. Conclusion Our combinatorial approach of in silico, cellular, and functional analysis is a powerful strategy to determine pathogenicity and FH disease mechanisms which may provide opportunitites for novel therapeutic strategies.
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Affiliation(s)
- Aseel A. Jawabri
- Department of Genetics and Genomics, College of Medicine and Health Sciences, United Arab Emirates University, Abu Dhabi, United Arab Emirates
| | - Anne John
- Department of Genetics and Genomics, College of Medicine and Health Sciences, United Arab Emirates University, Abu Dhabi, United Arab Emirates
| | | | - Radwa E. Mahgoub
- College of Pharmacy, Al-Ain University, Abu Dhabi, United Arab Emirates
| | - Mohammad I. K. Hamad
- Department of Anatomy, College of Medicine and Health Sciences, United Arab Emirates University, Abu Dhabi, United Arab Emirates
| | - Maha T. Barakat
- Research Institute, Imperial College London Diabetes Centre (ICLDC), Abu Dhabi, United Arab Emirates
| | - Bindu Shobi
- Research Institute, Imperial College London Diabetes Centre (ICLDC), Abu Dhabi, United Arab Emirates
| | - Hinda Daggag
- Research Institute, Imperial College London Diabetes Centre (ICLDC), Abu Dhabi, United Arab Emirates
| | - Bassam R. Ali
- Department of Genetics and Genomics, College of Medicine and Health Sciences, United Arab Emirates University, Abu Dhabi, United Arab Emirates
- ASPIRE Precision Medicine Research Institute Abu Dhabi, United Arab Emirates University, Al Ain, United Arab Emirates
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Rodríguez-Gutiérrez PG, Hernández-Flores TDJ, Zepeda-Olmos PM, Reyes-Rodríguez CD, Robles-Espinoza K, Solís-Gómez U, González-García JR, Magaña-Torres MT. High Prevalence of Familial Hypercholesterolemia Due to the Founder Effect of the LDLR c.2271del Variant in Communities of Oaxaca, Mexico. Arch Med Res 2024; 55:102971. [PMID: 38513336 DOI: 10.1016/j.arcmed.2024.102971] [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: 08/11/2023] [Revised: 01/31/2024] [Accepted: 02/13/2024] [Indexed: 03/23/2024]
Abstract
INTRODUCTION In Mexico, familial hypercholesterolemia (FH) is underdiagnosed, but population screening in small communities where at least one homozygous patient has already been detected results in a useful and inexpensive approach to reduce this problem. Considering that we previously reported nine homozygous cases from the state of Oaxaca, we decided to perform a population screening to identify patients with FH and to describe both their biochemical and genetic characteristics. METHODS LDL cholesterol (LDLc) was quantified in 2,093 individuals from 11 communities in Oaxaca; either adults with LDLc levels ≥170 mg/dL or children with LDLc ≥130 mg/dL were classified as suggestive of FH and therefore included in the genetic study. LDLR and APOB (547bp fragment of exon 26) genes were screened by sequencing and MLPA analysis. RESULTS Two hundred and five individuals had suggestive FH, with a mean LDLc of 223 ± 54 mg/dL (range: 131-383 mg/dL). Two pathogenic variants in the LDLR gene were detected in 149 individuals: c.-139_-130del (n = 1) and c.2271del (n = 148). All patients had a heterozygous genotype. With the cascade screening of their relatives (n = 177), 15 heterozygous individuals for the c.2271del variant were identified, presenting a mean LDLc of 133 ± 35 mg/dL (range: 60-168 mg/dL). CONCLUSIONS The FH frequency in this study was 7.8% (164/2093), the highest reported worldwide. A founder effect combined with inbreeding could be responsible for the high percentage of patients with the LDLR c.2271del variant (99.4%), which allowed us to detect both significant biochemical heterogeneity and incomplete penetrance; hence, we assumed the presence of phenotype-modifying variants.
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Affiliation(s)
- Perla Graciela Rodríguez-Gutiérrez
- Doctorado en Genética Humana, Centro Universitario de Ciencias de la Salud, Universidad de Guadalajara, Guadalajara, Jalisco, México; División de Genética, Centro de Investigación Biomédica de Occidente, Instituto Mexicano del Seguro Social, Guadalajara, Jalisco, México
| | - Teresita de Jesús Hernández-Flores
- Departamento de Disciplinas Filosófico, Metodológicas e Instrumentales. Centro Universitario de Ciencias de la Salud, Universidad de Guadalajara, Guadalajara, Jalisco, México
| | - Paola Montserrat Zepeda-Olmos
- Doctorado en Genética Humana, Centro Universitario de Ciencias de la Salud, Universidad de Guadalajara, Guadalajara, Jalisco, México; División de Genética, Centro de Investigación Biomédica de Occidente, Instituto Mexicano del Seguro Social, Guadalajara, Jalisco, México
| | - Christian Daniel Reyes-Rodríguez
- Doctorado en Genética Humana, Centro Universitario de Ciencias de la Salud, Universidad de Guadalajara, Guadalajara, Jalisco, México; División de Genética, Centro de Investigación Biomédica de Occidente, Instituto Mexicano del Seguro Social, Guadalajara, Jalisco, México
| | - Kiabeth Robles-Espinoza
- Doctorado en Genética Humana, Centro Universitario de Ciencias de la Salud, Universidad de Guadalajara, Guadalajara, Jalisco, México; División de Genética, Centro de Investigación Biomédica de Occidente, Instituto Mexicano del Seguro Social, Guadalajara, Jalisco, México
| | - Ulises Solís-Gómez
- Hospital Regional, Instituto de Seguridad y Servicios Sociales de los Trabajadores del Estado, Tepic Aquiles Calles Ramírez, Tepic, Nayarit, México
| | - Juan Ramón González-García
- División de Genética, Centro de Investigación Biomédica de Occidente, Instituto Mexicano del Seguro Social, Guadalajara, Jalisco, México
| | - María Teresa Magaña-Torres
- División de Genética, Centro de Investigación Biomédica de Occidente, Instituto Mexicano del Seguro Social, Guadalajara, Jalisco, México.
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Hummelgaard S, Vilstrup JP, Gustafsen C, Glerup S, Weyer K. Targeting PCSK9 to tackle cardiovascular disease. Pharmacol Ther 2023; 249:108480. [PMID: 37331523 DOI: 10.1016/j.pharmthera.2023.108480] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Revised: 06/07/2023] [Accepted: 06/14/2023] [Indexed: 06/20/2023]
Abstract
Lowering blood cholesterol levels efficiently reduces the risk of developing atherosclerotic cardiovascular disease (ASCVD), including coronary artery disease (CAD), which is the main cause of death worldwide. CAD is caused by plaque formation, comprising cholesterol deposits in the coronary arteries. Proprotein convertase subtilisin kexin/type 9 (PCSK9) was discovered in the early 2000s and later identified as a key regulator of cholesterol metabolism. PCSK9 induces lysosomal degradation of the low-density lipoprotein (LDL) receptor in the liver, which is responsible for clearing LDL-cholesterol (LDL-C) from the circulation. Accordingly, gain-of-function PCSK9 mutations are causative of familial hypercholesterolemia, a severe condition with extremely high plasma cholesterol levels and increased ASCVD risk, whereas loss-of-function PCSK9 mutations are associated with very low LDL-C levels and protection against CAD. Since the discovery of PCSK9, extensive investigations in developing PCSK9 targeting therapies have been performed. The combined delineation of clear biology, genetic risk variants, and PCSK9 crystal structures have been major drivers in developing antagonistic molecules. Today, two antibody-based PCSK9 inhibitors have successfully progressed to clinical application and shown to be effective in reducing cholesterol levels and mitigating the risk of ASCVD events, including myocardial infarction, stroke, and death, without any major adverse effects. A third siRNA-based inhibitor has been FDA-approved but awaits cardiovascular outcome data. In this review, we outline the PCSK9 biology, focusing on the structure and nonsynonymous mutations reported in the PCSK9 gene and elaborate on PCSK9-lowering strategies under development. Finally, we discuss future perspectives with PCSK9 inhibition in other severe disorders beyond cardiovascular disease.
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Affiliation(s)
| | | | | | - Simon Glerup
- Department of Biomedicine, Aarhus University, Aarhus, Denmark; Draupnir Bio, INCUBA Skejby, Aarhus, Denmark
| | - Kathrin Weyer
- Department of Biomedicine, Aarhus University, Aarhus, Denmark.
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LDLR Gene Mutation p.Asp360His and Familial Hypercholesterolemia in a Mexican Community. Arch Med Res 2020; 51:153-159. [PMID: 32113782 DOI: 10.1016/j.arcmed.2019.12.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 11/12/2019] [Accepted: 12/31/2019] [Indexed: 11/24/2022]
Abstract
BACKGROUND Familial hypercholesterolemia (FH) is an autosomal dominant disease characterized by an increased LDL-cholesterol (LDLc) serum concentration and premature cardiovascular disease. Screening of small populations where at least one homozygous (HoFH) patient has been identified may be a proper approach for detecting FH patients. Previously, we reported an HoFH patient carrying the mutation p.Asp360His LDLR, who was born in the Mexican community El Triunfo (Quimixtlan, Puebla). AIM OF THE STUDY To identify patients with familial hypercholesterolemia in the community El Triunfo and to describe their clinical and biochemical characteristics. METHODS We studied 308 individuals by quantifying lipid levels and by DNA sequencing. RESULTS Sixteen of 308 individuals presented an LDLc level >170 mg/dL and all of them turned out to be heterozygous for the LDLR p.Asp360His variant. Subsequently, 34 of their first-degree relatives (mainly siblings and parents) were genotyped rendering six additional HeFH patients, which resulted in 22 carriers of the mutated allele. The study of six LDLR polymorphisms in four unrelated individuals from the community (one HoFH and three HeFH) showed the same haplotype combination, suggesting a unique ancestral origin of the mutation. CONCLUSIONS The community El Triunfo, has the highest worldwide frequency ever reported of HeFH, with 7.14% (22/308, equivalent to 1/14 inhabitants). Since the HeFH patients showed variable biochemical expression, we suggest looking for factors with the potential to modify the phenotype. Finally, we stress the importance of establishing accurate LDLc cut-off points applicable to Mexican population for the diagnosis of FH.
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Setia N, Movva S, Balakrishnan P, Biji IK, Sawhney JPS, Puri R, Arora A, Puri RD, Saxena R, Mishra S, Apte S, Kulshrestha S, Ramprasad VL, Verma IC. Genetic analysis of familial hypercholesterolemia in Asian Indians: A single-center study. J Clin Lipidol 2020; 14:35-45. [PMID: 32044282 DOI: 10.1016/j.jacl.2019.12.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Revised: 12/27/2019] [Accepted: 12/27/2019] [Indexed: 11/16/2022]
Abstract
BACKGROUND Familial hypercholesterolemia (FH), an autosomal codominant disorder characterized by very high low-density lipoprotein cholesterol, is strongly associated with premature coronary artery disease. OBJECTIVES Molecular landscape of FH in Asian Indians is not well studied, although this ethnic group comprises a large proportion of the world population. Knowledge of mutations in these groups is useful for identifying persons affected with FH, saving their lives, and cascade screening in their relatives. METHODS Potential cases of FH (n = 100) were identified by criteria adapted for the Indian population from Dutch Lipid Clinic Network criteria. Pathogenic variants were analyzed in LDLR, APOB 100 (exons 26 and 29), PCSK9, and APOE genes using Sanger sequencing and multiplex ligation-dependent probe amplification technique. Cases in whom there were no pathogenic variants were tested by next-generation sequencing using a targeted panel of genes. RESULTS Thirty-eight pathogenic variants were identified in 47 of 100 unrelated probands. Of these variants, 33 were identified in LDLR, 3 in APOB, and 2 in PCSK9 genes. Ten pathogenic variants were novel. Mutations were detected in 91.4% of those subjects classified as definite, 40% as probable, and in 18.8% as possible FH cases based on modified Dutch Lipid Clinic Network criteria. A likely founder mutation in intron 10 (c.1587-1G>A) of LDLR gene was observed in 6 North Indian families. The conventional pathogenic variants in APOB and PCSK9 genes and those previously reported in LDLR gene among Asian Indians were not detected in this cohort. CONCLUSION This study demonstrates genetic heterogeneity of FH in India. The variants observed were different from those described in Western populations. Next-generation sequencing technology helped identify new mutations in APOB gene, suggesting that in less-studied populations, it is better to sequence the whole gene rather than test for specific mutations.
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Affiliation(s)
- Nitika Setia
- Institute of Medical Genetics and Genomics, Sir Ganga Ram Hospital, New Delhi, India.
| | - Sireesha Movva
- Institute of Medical Genetics and Genomics, Sir Ganga Ram Hospital, New Delhi, India
| | - Prahlad Balakrishnan
- Institute of Medical Genetics and Genomics, Sir Ganga Ram Hospital, New Delhi, India
| | - Ishpreet K Biji
- Institute of Medical Genetics and Genomics, Sir Ganga Ram Hospital, New Delhi, India
| | | | - Raman Puri
- Department of Cardiology, Indrapratha Apollo Hospital, New Delhi, India
| | - Anjali Arora
- Department of Cardiology, Sir Ganga Ram Hospital, New Delhi, India
| | - Ratna D Puri
- Institute of Medical Genetics and Genomics, Sir Ganga Ram Hospital, New Delhi, India
| | - Renu Saxena
- Institute of Medical Genetics and Genomics, Sir Ganga Ram Hospital, New Delhi, India
| | | | | | - Samarth Kulshrestha
- Institute of Medical Genetics and Genomics, Sir Ganga Ram Hospital, New Delhi, India
| | | | - Ishwar C Verma
- Institute of Medical Genetics and Genomics, Sir Ganga Ram Hospital, New Delhi, India.
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Panach K, Garg A, Ahmad Z. Heterozygous Null LDLR Mutation in a Familial Hypercholesterolemia Patient With an Atypical Presentation Because of Alcohol Abuse. ACTA ACUST UNITED AC 2019; 10:CIRCGENETICS.117.001767. [PMID: 28993407 DOI: 10.1161/circgenetics.117.001767] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Kamaldeep Panach
- From the Division of Endocrinology (K.P.), Department of Internal Medicine (K.P.), and Department of Internal Medicine, Division of Nutrition and Metabolic Diseases, Center for Human Nutrition, UT Southwestern Medical Center, Dallas, TX (A.G., Z.A.).
| | - Abhimanyu Garg
- From the Division of Endocrinology (K.P.), Department of Internal Medicine (K.P.), and Department of Internal Medicine, Division of Nutrition and Metabolic Diseases, Center for Human Nutrition, UT Southwestern Medical Center, Dallas, TX (A.G., Z.A.)
| | - Zahid Ahmad
- From the Division of Endocrinology (K.P.), Department of Internal Medicine (K.P.), and Department of Internal Medicine, Division of Nutrition and Metabolic Diseases, Center for Human Nutrition, UT Southwestern Medical Center, Dallas, TX (A.G., Z.A.)
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Alhababi D, Zayed H. Spectrum of mutations of familial hypercholesterolemia in the 22 Arab countries. Atherosclerosis 2018; 279:62-72. [PMID: 30415195 DOI: 10.1016/j.atherosclerosis.2018.10.022] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Revised: 10/15/2018] [Accepted: 10/18/2018] [Indexed: 11/27/2022]
Abstract
BACKGROUND AND AIMS Familial hypercholesterolemia (FH) is an inherited genetic disorder of lipid metabolism characterized by a high serum LDL-cholesterol profile and xanthoma formation, and FH increases the risk of premature atherosclerosis and cardiovascular disease (CVD). Mutations in the low-density lipoprotein (LDLR), apolipoprotein B (APOB), proprotein convertase subtilisin/kexin 9 (PCSK9), and LDLRAP1 genes have been associated with FH. Although FH is a major risk for CVD, the disease prevalence and its underlying molecular basis in the 22 Arab countries are still understudied. This study aimed to analyze all peer-reviewed studies related to the prevalence of FH and its causative mutations in the 22 Arab countries. METHODS We searched five literature databases (Scopus, Science Direct, Web of Science, PubMed, and Google Scholar) from inception until June 2018, using all possible search terms to capture all of the genetic and prevalence data related to Arab patients with FH. RESULTS A total of 5,484 titles and abstracts were identified; 51 studies met our inclusion criteria for the final systematic review. Fifty-one mutations in Arab patients with FH were identified in only eight Arab countries; 47 were identified in the LDLR gene, two in the PCSK9 gene, and two in LDLRAP1 gene. Twenty mutations in the LDLR gene were distinctive to Arab patients. A few studies reported prevalence estimates, ranging from 0.4% to 6.8%. CONCLUSIONS This is the first systematic review to dissect the up-to-date status of the genetic epidemiology of Arab patients with FH. It seems that FH is underdiagnosed and that its prevalence is understudied due to the dearth of published information about Arab patients with FH. Therefore, there is a need for well-controlled genetic epidemiological studies on Arab patients with FH.
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Affiliation(s)
- Dalal Alhababi
- College of Health Sciences, Biomedical Program, Qatar University, Doha, Qatar
| | - Hatem Zayed
- College of Health Sciences, Biomedical Program, Qatar University, Doha, Qatar.
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Hernández Flores TDJ, González García JR, Colima Fausto AG, Vázquez Cárdenas NA, Sánchez López Y, Zarate Morales CA, Magaña Torres MT. Screening of LDLR and APOB gene mutations in Mexican patients with homozygous familial hypercholesterolemia. J Clin Lipidol 2018; 12:693-701. [PMID: 29576406 DOI: 10.1016/j.jacl.2018.02.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Revised: 02/20/2018] [Accepted: 02/24/2018] [Indexed: 12/21/2022]
Abstract
BACKGROUND Familial hypercholesterolemia (FH) is an autosomal dominant disorder that causes accumulation of serum low-density lipoprotein cholesterol and premature cardiovascular disease. It is mainly related to mutations in the LDLR gene. Homozygous FH (HoFH) patients have the most severe form of the disease accounting for a worldwide prevalence of 1:1,000,000. In Mexico, at least 5 cases of HoFH have been reported. OBJECTIVE The aim of this study was to describe the clinical, biochemical, and molecular data observed in patients with HoFH phenotype. METHODS We included 13 patients, belonging to 11 families, with clinical and biochemical diagnoses suggestive of HoFH. Molecular analyses of the LDLR and APOB genes were performed by means of polymerase chain reaction followed by Sanger sequencing. RESULTS The causal mutation of HoFH was found in 8 of 11 unrelated patients. Excepting 1, all were true homozygotes. Six different variants in LDLR were identified: c.-139delCTCCCCCTGC, p.Glu140Lys, p.Asp360His, p.Asn405Lys, p.Ala755Glyfs*7, and p.Leu759Serfs*6. Of these, p.Asp360His and p.Asn405Lys were detected for the first time in Mexico; p.Leu759Serfs*6 showed to be the most frequent (43.7% of the alleles 7/16), and c.-139delCTCCCCCTGC is a new variant located in the promoter region. CONCLUSIONS This work increases knowledge of biochemical and genetic features in Mexican patients with HoFH. A novel mutation in the LDLR gene promoter was detected: c.-139delCTCCCCCTGC, which possibly inhibits its expression.
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Affiliation(s)
- Teresita De Jesús Hernández Flores
- División de Genética, Centro de Investigación Biomédica de Occidente, Instituto Mexicano del Seguro Social, Guadalajara, Jalisco, México; Doctorado en Genética Humana, Centro Universitario de Ciencias de la Salud, Universidad de Guadalajara, Guadalajara, Jalisco, México
| | - Juan Ramón González García
- División de Genética, Centro de Investigación Biomédica de Occidente, Instituto Mexicano del Seguro Social, Guadalajara, Jalisco, México
| | - Ana Gabriela Colima Fausto
- División de Genética, Centro de Investigación Biomédica de Occidente, Instituto Mexicano del Seguro Social, Guadalajara, Jalisco, México; Doctorado en Genética Humana, Centro Universitario de Ciencias de la Salud, Universidad de Guadalajara, Guadalajara, Jalisco, México
| | | | - Yoaly Sánchez López
- División de Genética, Centro de Investigación Biomédica de Occidente, Instituto Mexicano del Seguro Social, Guadalajara, Jalisco, México; Doctorado en Genética Humana, Centro Universitario de Ciencias de la Salud, Universidad de Guadalajara, Guadalajara, Jalisco, México
| | - César Augusto Zarate Morales
- Hospital "Presidente Juárez" del Instituto de Seguridad y Servicios Sociales de los Trabajadores del Estado (ISSSTE), Oaxaca, Oax, México
| | - María Teresa Magaña Torres
- División de Genética, Centro de Investigación Biomédica de Occidente, Instituto Mexicano del Seguro Social, Guadalajara, Jalisco, México; Doctorado en Genética Humana, Centro Universitario de Ciencias de la Salud, Universidad de Guadalajara, Guadalajara, Jalisco, México.
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Chora JR, Medeiros AM, Alves AC, Bourbon M. Analysis of publicly available LDLR, APOB, and PCSK9 variants associated with familial hypercholesterolemia: application of ACMG guidelines and implications for familial hypercholesterolemia diagnosis. Genet Med 2017; 20:591-598. [PMID: 29261184 DOI: 10.1038/gim.2017.151] [Citation(s) in RCA: 78] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Accepted: 07/26/2017] [Indexed: 01/15/2023] Open
Abstract
PurposeFamilial hypercholesterolemia (FH) is an autosomal disorder of lipid metabolism presenting with increased cardiovascular risk. Although more than 1,700 variants have been associated with FH, the great majority have not been functionally proved to affect the low-density lipoprotein receptor cycle. We aimed to classify all described variants associated with FH and to establish the proportion of variants that lack evidence to support their pathogenicity.MethodsWe followed American College of Medical Genetics and Genomics (ACMG) guidelines for the classification, and collected information from a variety of databases and individual reports. A worldwide overview of publicly available FH variants was also performed.ResultsA total of 2,104 unique variants were identified as being associated with FH, but only 166 variants have been proven by complete in vitro functional studies to be causative of disease. Additionally, applying the ACMG guidelines, 1,097 variants were considered pathogenic or likely pathogenic. Only seven variants were found in all five continents.ConclusionThe lack of functional evidence for about 85% of all variants found in FH patients can compromise FH diagnosis and patient prognosis. ACMG classification improves variant interpretation, but functional studies are necessary to understand the effect of about 40% of all variants reported. Nevertheless, ACMG guidelines need to be adapted to FH for a better diagnosis.
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Affiliation(s)
- Joana Rita Chora
- Unidade I&D, Grupo de Investigação Cardiovascular, Departamento de Promoção da Saúde e Doenças Não Transmissíveis, Instituto Nacional de Saúde Doutor Ricardo Jorge, Lisbon, Portugal.,University of Lisboa, Faculty of Sciences, BioISI-Biosystems & Integrative Sciences Institute, Lisbon, Portugal
| | - Ana Margarida Medeiros
- Unidade I&D, Grupo de Investigação Cardiovascular, Departamento de Promoção da Saúde e Doenças Não Transmissíveis, Instituto Nacional de Saúde Doutor Ricardo Jorge, Lisbon, Portugal.,University of Lisboa, Faculty of Sciences, BioISI-Biosystems & Integrative Sciences Institute, Lisbon, Portugal
| | - Ana Catarina Alves
- Unidade I&D, Grupo de Investigação Cardiovascular, Departamento de Promoção da Saúde e Doenças Não Transmissíveis, Instituto Nacional de Saúde Doutor Ricardo Jorge, Lisbon, Portugal.,University of Lisboa, Faculty of Sciences, BioISI-Biosystems & Integrative Sciences Institute, Lisbon, Portugal
| | - Mafalda Bourbon
- Unidade I&D, Grupo de Investigação Cardiovascular, Departamento de Promoção da Saúde e Doenças Não Transmissíveis, Instituto Nacional de Saúde Doutor Ricardo Jorge, Lisbon, Portugal.,University of Lisboa, Faculty of Sciences, BioISI-Biosystems & Integrative Sciences Institute, Lisbon, Portugal
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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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Bañares VG, Corral P, Medeiros AM, Araujo MB, Lozada A, Bustamante J, Cerretini R, López G, Bourbon M, Schreier LE. Preliminary spectrum of genetic variants in familial hypercholesterolemia in Argentina. J Clin Lipidol 2017; 11:524-531. [DOI: 10.1016/j.jacl.2017.02.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Revised: 02/12/2017] [Accepted: 02/14/2017] [Indexed: 01/07/2023]
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Santos RD, Bourbon M, Alonso R, Cuevas A, Vasques-Cardenas NA, Pereira AC, Merchan A, Alves AC, Medeiros AM, Jannes CE, Krieger JE, Schreier L, Perez de Isla L, Magaña-Torres MT, Stoll M, Mata N, Dell Oca N, Corral P, Asenjo S, Bañares VG, Reyes X, Mata P. Clinical and molecular aspects of familial hypercholesterolemia in Ibero-American countries. J Clin Lipidol 2017; 11:160-166. [DOI: 10.1016/j.jacl.2016.11.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Accepted: 11/10/2016] [Indexed: 11/26/2022]
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Mehta R, Zubirán R, Martagón AJ, Vazquez-Cárdenas A, Segura-Kato Y, Tusié-Luna MT, Aguilar-Salinas CA. The panorama of familial hypercholesterolemia in Latin America: a systematic review. J Lipid Res 2016; 57:2115-2129. [PMID: 27777316 PMCID: PMC5321217 DOI: 10.1194/jlr.r072231] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2016] [Revised: 10/23/2016] [Indexed: 11/20/2022] Open
Abstract
The burden caused by familial hypercholesterolemia (FH) varies among countries and ethnic groups. The prevalence and characteristics of FH in Latin American (LA) countries is largely unknown. We present a systematic review (following the PRISMA statement) of FH in LA countries. The epidemiology, genetics, screening, management, and unique challenges encountered in these countries are discussed. Published reports discussing FH in Hispanic or LA groups was considered for analysis. Thirty studies were included representing 10 countries. The bulk of the data was generated in Brazil and Mexico. Few countries have registries and there was little commonality in FH mutations between LA countries. LDL receptor mutations predominate; APOB and PCSK9 mutations are rare. No mutation was found in an FH gene in nearly 50% of cases. In addition, some country-specific mutations have been reported. Scant information exists regarding models of care, cascade screening, cost, treatment effectiveness, morbidity, and mortality. In conclusion, FH is largely underdiagnosed and undertreated in the LA region. The genetic admixture with indigenous populations, producing mestizo's groups, may influence the mutational findings in Latin America. Potential opportunities to close gaps in knowledge and health care are identified.
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Affiliation(s)
- Roopa Mehta
- Departamento de Endocrinologia y Metabolismo, Instituto Nacional de Ciencias Médicas y Nutrición "Salvador Zubirán", Mexico City, Mexico
| | - Rafael Zubirán
- Departamento de Endocrinologia y Metabolismo, Instituto Nacional de Ciencias Médicas y Nutrición "Salvador Zubirán", Mexico City, Mexico
| | | | | | - Yayoi Segura-Kato
- Departamento de Endocrinologia y Metabolismo, Instituto Nacional de Ciencias Médicas y Nutrición "Salvador Zubirán", Mexico City, Mexico; Unidad de Biología Molecular y Medicina Genómica Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - María Teresa Tusié-Luna
- Departamento de Endocrinologia y Metabolismo, Instituto Nacional de Ciencias Médicas y Nutrición "Salvador Zubirán", Mexico City, Mexico; Unidad de Biología Molecular y Medicina Genómica Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Carlos A Aguilar-Salinas
- Departamento de Endocrinologia y Metabolismo, Instituto Nacional de Ciencias Médicas y Nutrición "Salvador Zubirán", Mexico City, Mexico.
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Predictors of cardiovascular events after one year of molecular screening for Familial hypercholesterolemia. Atherosclerosis 2016; 250:144-50. [PMID: 27214396 DOI: 10.1016/j.atherosclerosis.2016.05.023] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Revised: 05/09/2016] [Accepted: 05/11/2016] [Indexed: 12/17/2022]
Abstract
BACKGROUND AND AIMS This study reports the first year follow-up of individuals enrolled in Brazil's genetic cascade screening program for Familial Hypercholesterolemia (FH), Hipercol Brasil. Predictors for the occurrence of cardiovascular (CV) events in individuals screened for FH were studied. METHODS This is an open prospective cohort of individuals who were included in a cascade genetic screening program for FH. The first prospective follow-up was carried out one year after patients received their genetic test result. Individuals included in this study were index cases (probands) and relatives with identified (M +) or not genetic mutations (M -). Logistic regression analysis was performed to determine predictive variables for the occurrence of CV events censored at one-year of follow-up. RESULTS A total of 818 subjects were included, 47 first CV events were ascertained, with 14 (29.7%) being fatal. For index cases, the only factor independently associated with increased risk of CV events was the presence of corneal arcus (OR: 9.39; 95% CI: 2.46-35.82). There was an inverse association of CV events with higher HDL-cholesterol levels (OR: 0.95; 95% CI: 0.90-0.99). For M+ relatives, risk factors associated with increased CV events risk were diabetes mellitus (OR: 7.97; 95% CI: 2.07-30.66) and tobacco consumption (OR: 3.70; 95% CI: 1.09-12.50). CONCLUSIONS A high one-year incidence of CV events was found in this cascade-screening cohort. Predictors of events differed between index cases and relatives and can be useful for the development of preventive efforts in this highly susceptible group of individuals.
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Homozygous familial hypercholesterolemia: the c.1055G>A mutation in the LDLR gene and clinical heterogeneity. J Clin Lipidol 2014; 8:525-7. [PMID: 25234566 DOI: 10.1016/j.jacl.2014.05.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Revised: 05/12/2014] [Accepted: 05/18/2014] [Indexed: 11/20/2022]
Abstract
Familial hypercholesterolemia (FH) is a world public health issue because of its high frequency, morbidity, and mortality. FH is characterized by elevated plasma low-density lipoprotein cholesterol (LDL-C) levels and a high risk for premature cardiovascular disease. We report an 8-year-old male with homozygous familial hypercholesterolemia. The clinical and biochemical characteristics of this case were bilateral corneal arcus, xanthomas in several body parts, severe stenosis of the left carotid artery and serum total cholesterol levels of 782.0 mg/dL and 715.0 mg/dL LDL-C. The initial treatment was atorvastatin (40 mg) and ezetimibe (20 mg), with no satisfactory response. LDLR gene was analyzed and homozygosity for c.1055G>A mutation was observed, resulting in an amino acid change from cysteine to tyrosine in codon 352 (p.Cys352Tyr). This mutation is known as Mexico 2 and has only been observed in the Mexican population. Both parents and siblings were carriers of the same mutation, but the paternal grandmother and the father of the index case showed the phenomenon of incomplete penetrance. With the analysis 5 polymorphisms (rs1003723C>T, rs5930A>G, rs688C>T, rs5929T>C and rs5927A>G), a common ancestor for the mutation can be suggested and linkage to TGTCG haplotype.
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Vishwanath R, Hemphill LC. Familial hypercholesterolemia and estimation of US patients eligible for low-density lipoprotein apheresis after maximally tolerated lipid-lowering therapy. J Clin Lipidol 2014; 8:18-28. [DOI: 10.1016/j.jacl.2013.11.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Revised: 09/27/2013] [Accepted: 11/01/2013] [Indexed: 10/26/2022]
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Tejedor MT, Cenarro A, Tejedor D, Stef M, Palacios L, de Castro I, García-Otín ÁL, Monteagudo LV, Civeira F, Pocovi M. New contributions to the study of common double mutants in the human LDL receptor gene. THE SCIENCE OF NATURE - NATURWISSENSCHAFTEN 2011; 98:943-9. [DOI: 10.1007/s00114-011-0845-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2011] [Revised: 09/02/2011] [Accepted: 09/06/2011] [Indexed: 03/08/2023]
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