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Perera SD, Hegele RA. Genetic variation in apolipoprotein A-V in hypertriglyceridemia. Curr Opin Lipidol 2024; 35:66-77. [PMID: 38117614 PMCID: PMC10919278 DOI: 10.1097/mol.0000000000000916] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2023]
Abstract
PURPOSE OF REVIEW While biallelic rare APOA5 pathogenic loss-of-function (LOF) variants cause familial chylomicronemia syndrome, heterozygosity for such variants is associated with highly variable triglyceride phenotypes ranging from normal to severe hypertriglyceridemia, often in the same individual at different time points. Here we provide an updated overview of rare APOA5 variants in hypertriglyceridemia. RECENT FINDINGS Currently, most variants in APOA5 that are considered to be pathogenic according to guidelines of the American College of Medical Genetics and Genomics are those resulting in premature termination codons. There are minimal high quality functional data on the impact of most rare APOA5 missense variants; many are considered as variants of unknown or uncertain significance. Furthermore, particular common polymorphisms of APOA5 , such as p.Ser19Trp and p.Gly185Cys in Caucasian and Asian populations, respectively, are statistically overrepresented in hypertriglyceridemia cohorts and are sometimes misattributed as being causal for chylomicronemia, when they are merely risk alleles for hypertriglyceridemia. SUMMARY Both biallelic and monoallelic LOF variants in APOA5 are associated with severe hypertriglyceridemia, although the biochemical phenotype in the monoallelic state is highly variable and is often exacerbated by secondary factors. Currently, with few exceptions, the principal definitive mechanism for APOA5 pathogenicity is through premature truncation. The pathogenic mechanisms of most missense variants in APOA5 remain unclear and require additional functional experiments or family studies.
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Affiliation(s)
- Shehan D Perera
- Departments of Biochemistry and Medicine, Schulich School of Medicine and Dentistry, Western University, 1151 Richmond Street North, London, Ontario, Canada
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Ariza MJ, Rioja J, Ibarretxe D, Camacho A, Díaz-Díaz JL, Mangas A, Carbayo-Herencia JA, Ruiz-Ocaña P, Lamíquiz-Moneo I, Mosquera D, Sáenz P, Masana L, Muñiz-Grijalvo O, Pérez-Calahorra S, Valdivielso P, Suárez Tembra M, Iglesias GP, Carbayo Herencia J, Guerrero Buitrago C, Vila L, Morales Coca C, Llargués Rocabruna E, Perea Castillo V, Pedro-Botet J, Climent E, Mauri Pont M, Pinto X, Ortega Martínez de la Victoria E, Amor J, Zambón Rados D, Blanco Vaca F, Ramiro Lozano J, Fuentes Jiménez F, Soler I, Ferrer C, Zamora Cervantes A, Vila Belmonte A, Novoa Mogollón F, Sanchez-Hernández R, Expósito Montesdeoca A, Romero Jiménez M, González García M, Bueno Díez M, Brea Hernando A, Lahoz C, Mostaza Prieto J, Millán Núñez-Cortés J, Reinares García L, Blanco Echevarría A, Ariza Corbo MJ, Rioja Villodres J, Sánchez-Chaparro M, Jansen Chaparro S, Sáenz Aranzubía P, Martorell Mateu E, Almagro Múgica F, Muñiz Grijalvo O, Masana Martín L, Plana Gil N, Ibarretxe Gerediaga D, Rodríguez Borjabad C, Zabala López S, Hernández Mijares A, Ascaso Gimilio J, Pérez García L, Civeira Murillo F, Pérez-Calahorra S, Lamiquiz-Moneo I, Mateo Gallego R, Marco Benedí V, Ferrando Vela J. Molecular basis of the familial chylomicronemia syndrome in patients from the National Dyslipidemia Registry of the Spanish Atherosclerosis Society. J Clin Lipidol 2018; 12:1482-1492.e3. [DOI: 10.1016/j.jacl.2018.07.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Revised: 07/09/2018] [Accepted: 07/24/2018] [Indexed: 01/16/2023]
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Clinical and biochemical features of different molecular etiologies of familial chylomicronemia. J Clin Lipidol 2018; 12:920-927.e4. [DOI: 10.1016/j.jacl.2018.03.093] [Citation(s) in RCA: 68] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Revised: 03/27/2018] [Accepted: 03/30/2018] [Indexed: 12/21/2022]
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Benes LB, Brandt EJ, Davidson MH. Advances in diagnosis and potential therapeutic options for familial chylomicronemia syndrome. Expert Opin Orphan Drugs 2018. [DOI: 10.1080/21678707.2018.1419863] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Lane B. Benes
- Section of Cardiology, The University of Chicago Medicine, Chicago, IL, USA
| | - Eric J. Brandt
- Section of Cardiology, Yale University School of Medicine, New Haven, CT, USA
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Ram R, Wakil S, Muiya N, Andres E, Mazhar N, Hagos S, Alshahid M, Meyer B, Morahan G, Dzimiri N. A common variant association study in ethnic Saudi Arabs reveals novel susceptibility loci for hypertriglyceridemia. Clin Genet 2017; 91:371-378. [DOI: 10.1111/cge.12859] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Revised: 08/30/2016] [Accepted: 08/30/2016] [Indexed: 12/15/2022]
Affiliation(s)
- R. Ram
- Centre for Diabetes Research, The Harry Perkinsn Institute for Medical Research Perth WA Australia
- Centre for Medical ResearchUniversity of Western Australia Perth WA Australia
| | - S.M. Wakil
- Genetics DepartmentKing Faisal Specialist Hospital and Research Centre Riyadh KSA
| | - N.P. Muiya
- Genetics DepartmentKing Faisal Specialist Hospital and Research Centre Riyadh KSA
| | - E. Andres
- Genetics DepartmentKing Faisal Specialist Hospital and Research Centre Riyadh KSA
| | - N. Mazhar
- Genetics DepartmentKing Faisal Specialist Hospital and Research Centre Riyadh KSA
| | - S. Hagos
- Genetics DepartmentKing Faisal Specialist Hospital and Research Centre Riyadh KSA
| | - M. Alshahid
- King Faisal Heart InstituteKing Faisal Specialist Hospital and Research Centre Riyadh KSA
| | - B.F. Meyer
- Genetics DepartmentKing Faisal Specialist Hospital and Research Centre Riyadh KSA
| | - G. Morahan
- Centre for Diabetes Research, The Harry Perkinsn Institute for Medical Research Perth WA Australia
- Centre for Medical ResearchUniversity of Western Australia Perth WA Australia
| | - N. Dzimiri
- Genetics DepartmentKing Faisal Specialist Hospital and Research Centre Riyadh KSA
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Thériault S, Don-Wauchope A, Chong M, Lali R, Morrison KM, Paré G. Frameshift mutation in the APOA5 gene causing hypertriglyceridemia in a Pakistani family: Management and considerations for cardiovascular risk. J Clin Lipidol 2016; 10:1272-7. [PMID: 27678447 DOI: 10.1016/j.jacl.2016.07.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2016] [Revised: 05/24/2016] [Accepted: 07/29/2016] [Indexed: 10/21/2022]
Abstract
We report a novel homozygous apolipoprotein A5 (APOA5) frameshift mutation (c.G425del-C, p.Arg143AlafsTer57) identified in a 12-year-old boy of Pakistani origin with severe hypertriglyceridemia (up to 35 mmol/L) and type V hyperlipoproteinemia. The patient did not respond to fibrate therapy, but his condition improved under a very low fat diet, although compliance was suboptimal. Heterozygous status was detected in both parents (consanguineous union) and one sibling, all showing moderate hypertriglyceridemia (between 5 and 10 mmol/L). There was a significant family history of premature cardiovascular disease. The index case was also diagnosed with a coronary artery anomaly. Considering the recently reported association of rare mutations in APOA5 with the risk of early myocardial infarction, we discuss the implications of these findings for the young man and his family.
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Affiliation(s)
- Sébastien Thériault
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada
| | - Andrew Don-Wauchope
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada
| | - Michael Chong
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada
| | - Ricky Lali
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada
| | | | - Guillaume Paré
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada.
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Therapeutic Targets of Triglyceride Metabolism as Informed by Human Genetics. Trends Mol Med 2016; 22:328-340. [DOI: 10.1016/j.molmed.2016.02.005] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Revised: 02/17/2016] [Accepted: 02/18/2016] [Indexed: 12/24/2022]
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Clinical and genetic features of 3 patients with familial chylomicronemia due to mutations in GPIHBP1 gene. J Clin Lipidol 2016; 10:915-921.e4. [PMID: 27578123 DOI: 10.1016/j.jacl.2016.03.009] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Revised: 03/11/2016] [Accepted: 03/12/2016] [Indexed: 12/30/2022]
Abstract
BACKGROUND Familial chylomicronemia is a recessive disorder that may be due to mutations in lipoprotein lipase (LPL) and in other proteins such as apolipoprotein C-II and apolipoprotein A-V (activators of LPL), GPIHBP1 (the molecular platform required for LPL activity on endothelial surface), and LMF1 (a factor required for intracellular formation of active LPL). METHODS We sequenced the familial chylomicronemia candidate genes in 2 adult females presenting long-standing hypertriglyceridemia and a history of acute pancreatitis. RESULTS Both probands had plasma triglyceride >10 mmol/L but no mutations in the LPL gene. The sequence of the other candidate genes showed that one patient was homozygous for a novel missense mutation p.(Cys83Arg), and the other was homozygous for a previously reported nonsense mutation p.(Cys 89*), respectively, in GPIHBP1. Family screening showed that the hypertriglyceridemic brother of the p.(Cys83Arg) homozygote was also homozygous for this mutation. He had no history of pancreatitis. The p.(Cys83Arg) heterozygous carriers had normal triglyceride levels. The substitution of a cysteine residue in the Ly6 domain of GPIHBP1 is predicted to abolish one of the disulfide bridges required to maintain the structure of GPIHBP1. The p.(Cys89*) mutation results in a truncated protein devoid of function. CONCLUSIONS Both mutant GPIHBP1 proteins are expected to be incapable of transferring LPL from the subendothelial space to the endothelial surface.
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Ariza MJ, Martínez-Hernández PL, Ibarretxe D, Rabacchi C, Rioja J, Grande-Aragón C, Plana N, Tarugi P, Olivecrona G, Calandra S, Valdivielso P. Novel mutations in the GPIHBP1 gene identified in 2 patients with recurrent acute pancreatitis. J Clin Lipidol 2015; 10:92-100.e1. [PMID: 26892125 DOI: 10.1016/j.jacl.2015.09.007] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Revised: 09/09/2015] [Accepted: 09/16/2015] [Indexed: 11/16/2022]
Abstract
BACKGROUND Glycosylphosphatidylinositol-anchored high-density lipoprotein-binding protein 1 (GPIHBP1) has been demonstrated to be essential for the in vivo function of lipoprotein lipase (LPL), the major triglyceride (TG)-hydrolyzing enzyme involved in the intravascular lipolysis of TG-rich lipoproteins. Recently, loss-of-function mutations of GPIHBP1 have been reported as the cause of type I hyperlipoproteinemia in several patients. METHODS Two unrelated patients were referred to our Lipid Units because of a severe hypertriglyceridemia and recurrent pancreatitis. We measured LPL activity in postheparin plasma and serum ApoCII and sequenced LPL, APOC2, and GPIHBP1. RESULTS The 2 patients exhibited very low LPL activity not associated with mutations in LPL gene or with ApoCII deficiency. The sequence of GPIHBP1 revealed 2 novel point mutations. One patient (proband 1) was found to be homozygous for a C>A transversion in exon 3 resulting in the conversion of threonine to lysine at position 80 (p.Thr80Lys). The other patient (proband 2) was found to be homozygous for a G>T transversion in the third base of the ATG translation initiation codon in exon 1, resulting in the conversion of methionine to isoleucine (p.Met1Ile). CONCLUSION In conclusion, we have identified 2 novel GPIHBP1 missense mutations in 2 unrelated patients as the cause of their severe hypertriglyceridemia.
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Affiliation(s)
- María José Ariza
- Department of Medicine and Dermatology, Lipids and Atherosclerosis Laboratory, CIMES, University of Málaga, Málaga, Spain.
| | | | - Daiana Ibarretxe
- Vascular Medicine and Metabolism Unit, Research Unit on Lipids and Atherosclerosis, Sant Joan University Hospital, Universitat Rovira i Virgili, IISPV, Spanish Biomedical Research Centre in Diabetes and Associated Metabolic Disorders (CIBERDEM), Reus, Spain
| | - Claudio Rabacchi
- Department of Life Sciences, University of Modena & Reggio Emilia, Modena, Italy
| | - José Rioja
- Department of Medicine and Dermatology, Lipids and Atherosclerosis Laboratory, CIMES, University of Málaga, Málaga, Spain
| | | | - Nuria Plana
- Vascular Medicine and Metabolism Unit, Research Unit on Lipids and Atherosclerosis, Sant Joan University Hospital, Universitat Rovira i Virgili, IISPV, Spanish Biomedical Research Centre in Diabetes and Associated Metabolic Disorders (CIBERDEM), Reus, Spain
| | - Patrizia Tarugi
- Department of Life Sciences, University of Modena & Reggio Emilia, Modena, Italy
| | - Gunilla Olivecrona
- Department of Medical Biosciences, Physiological Chemistry, Umeå University, Umeå, Sweden
| | - Sebastiano Calandra
- Department of Biomedical, Metabolic and Neural Sciences, University of Modena & Reggio Emilia Modena, Italy
| | - Pedro Valdivielso
- Department of Medicine and Dermatology, Lipids and Atherosclerosis Laboratory, CIMES, University of Málaga, Málaga, Spain; Internal Medicine Unit, Virgen de la Victoria University Hospital, Málaga, Spain
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Pisciotta L, Vitali C, Favari E, Fossa P, Adorni MP, Leone D, Artom N, Fresa R, Calabresi L, Calandra S, Bertolini S. A complex phenotype in a child with familial HDL deficiency due to a novel frameshift mutation in APOA1 gene (apoA-IGuastalla). J Clin Lipidol 2015; 9:837-846. [PMID: 26687706 DOI: 10.1016/j.jacl.2015.09.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Revised: 08/07/2015] [Accepted: 09/09/2015] [Indexed: 01/07/2023]
Abstract
BACKGROUND We describe a kindred with high-density lipoprotein (HDL) deficiency due to APOA1 gene mutation in which comorbidities affected the phenotypic expression of the disorder. METHODS An overweight boy with hypertriglyceridemia (HTG) and HDL deficiency (HDL cholesterol 0.39 mmol/L, apoA-I 40 mg/dL) was investigated. We sequenced the candidate genes for HTG (LPL, APOC2, APOA5, GPIHBP1, LMF1) and HDL deficiency (LCAT, ABCA1 and APOA1), analyzed HDL subpopulations, measured cholesterol efflux capacity (CEC) of sera and constructed a model of the mutant apoA-I. RESULTS No mutations in HTG-related genes, ABCA1 and LCAT were found. APOA1 sequence showed that the proband, his mother and maternal grandfather were heterozygous of a novel frameshift mutation (c.546_547delGC), which generated a truncated protein (p.[L159Afs*20]) containing 177 amino acids with an abnormal C-terminal tail of 19 amino acids. Trace amounts of this protein were detectable in plasma. Mutation carriers had reduced levels of LpA-I, preβ-HDL and large HDL and no detectable HDL-2 in their plasma; their sera had a reduced CEC specifically the ABCA1-mediated CEC. Metabolic syndrome in the proband explains the extremely low HDL cholesterol level (0.31 mmol/L), which was half of that found in the other carriers. The proband's mother and grandfather, both presenting low plasma low-density lipoprotein cholesterol, were carriers of the β-thalassemic trait, a condition known to be associated with a reduced low-density lipoprotein cholesterol and a reduced prevalence of cardiovascular disease. This trait might have delayed the development of atherosclerosis related to HDL deficiency. CONCLUSIONS In these heterozygotes for apoA-I truncation, the metabolic syndrome has deleterious effect on HDL system, whereas β-thalassemia trait may delay the onset of cardiovascular disease.
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Affiliation(s)
- Livia Pisciotta
- Department of Internal Medicine, University of Genoa, Genoa, Italy
| | - Cecilia Vitali
- Center E. Grossi Paoletti, Department of Pharmacological and Biomolecular Sciences, University of Milan, Milan, Italy
| | - Elda Favari
- Department of Pharmacy, University of Parma, Parma, Italy
| | - Paola Fossa
- Department of Pharmacy, University of Genoa, Genoa, Italy
| | | | - Daniela Leone
- Laboratory of Human Genetics, Galliera Hospital, Genoa, Italy
| | - Nathan Artom
- Department of Internal Medicine, University of Genoa, Genoa, Italy
| | - Raffaele Fresa
- Department of Internal Medicine, University of Genoa, Genoa, Italy
| | - Laura Calabresi
- Center E. Grossi Paoletti, Department of Pharmacological and Biomolecular Sciences, University of Milan, Milan, Italy
| | - Sebastiano Calandra
- Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy.
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Rabacchi C, Pisciotta L, Cefalù AB, Noto D, Fresa R, Tarugi P, Averna M, Bertolini S, Calandra S. Spectrum of mutations of the LPL gene identified in Italy in patients with severe hypertriglyceridemia. Atherosclerosis 2015; 241:79-86. [DOI: 10.1016/j.atherosclerosis.2015.04.815] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Revised: 04/24/2015] [Accepted: 04/26/2015] [Indexed: 12/20/2022]
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Buonuomo PS, Bartuli A, Rabacchi C, Bertolini S, Calandra S. A 3-day-old neonate with severe hypertriglyceridemia from novel mutations of the GPIHBP1 gene. J Clin Lipidol 2014; 9:265-70. [PMID: 25911085 DOI: 10.1016/j.jacl.2014.10.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Revised: 10/01/2014] [Accepted: 10/06/2014] [Indexed: 12/16/2022]
Abstract
BACKGROUND Familial chylomicronemia is a genetic defect of the intravascular lipolysis of triglyceride (TG)-rich lipoproteins. Intravascular lipolysis involves the TG-hydrolase lipoprotein lipase (LPL) as well as other factors such as apolipoprotein CII and apolipoprotein AV (activators of LPL), GPIHBP1 (the molecular platform required for LPL activity on endothelial surface), and LMF1 (a factor required for intracellular formation of active LPL). METHODS We sequenced the familial chylomicronemia candidate genes in a neonate with chylomicronemia. RESULTS A 3-day-old newborn was found to have chylomicronemia (plasma TG 18.8 mmol/L, 1.667 mg/dL). The discontinuation of breastfeeding for 24 hours reduced plasma TG to 2.3 mmol/L (201 mg/dL), whereas its resumption induced a sharp TG increase (7.9 mmol/L, 690 mg/dL). The child was switched to a low-fat diet, which was effective in maintaining TG level below 3.5 mmol/L (294 mg/dL) during the first months of life. The child was found to be a compound heterozygous for 2 novel mutations in GPIHBP1 gene. The first mutation was a 9-bp deletion and 4-bp insertion in exon 2, causing a frameshift that abolished the canonical termination codon TGA. The predicted translation product of the mutant messenger RNA is a peptide that contains 51 amino acids of the N-terminal end of the wild-type protein followed by 252 novel amino acids. The second mutation was a nucleotide change (c.319T>C), causing an amino acid substitution p.(Ser107Pro) predicted in silico to be damaging. CONCLUSIONS GPIHBP1 mutations should be considered in neonates with chylomicronemia negative for mutations in LPL gene.
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Affiliation(s)
| | - Andrea Bartuli
- Rare Diseases and Medical Genetics, Bambino Gesù Children Hospital, Rome, Italy
| | - Claudio Rabacchi
- Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Stefano Bertolini
- Department of Internal Medicine, University of Genova, Genova, Italy
| | - Sebastiano Calandra
- Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy.
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Molecular analysis of chylomicronemia in a clinical laboratory setting: Diagnosis of 13 cases of lipoprotein lipase deficiency. Clin Chim Acta 2014; 429:61-8. [DOI: 10.1016/j.cca.2013.11.025] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2013] [Revised: 11/09/2013] [Accepted: 11/22/2013] [Indexed: 01/05/2023]
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Stefanutti C, Gozzer M, Pisciotta L, D'Eufemia P, Bosco G, Morozzi C, Papadia F, Shafii M, Di Giacomo S, Bertolini S. A three month-old infant with severe hyperchylomicronemia: molecular diagnosis and extracorporeal treatment. ATHEROSCLEROSIS SUPP 2013; 14:73-6. [PMID: 23357145 DOI: 10.1016/j.atherosclerosissup.2012.10.020] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
OBJECTIVE Chylomicronemia syndrome presenting in childhood is a rare recessive disorder due to mutations of lipoprotein lipase (LPL) and more rarely of APOC2, APOA5, GPIHBP1 or LMF1 genes. It often requires urgent and suitable treatment to avoid acute pancreatitis. The aim of this study was the molecular characterization and treatment of a 3 month-old infant with plasma triglycerides (TG) > 300 mmol/L. METHODS All candidate genes were sequenced. The patient was submitted to one plasma-exchange (PEX) procedure and subsequently to a rigid lipid-lowering diet (milk: Monogen(®)). RESULTS The proband was homozygous for a novel LPL mutation (c.242G > A, p.G81D) which in silico results pathogenic. After PEX, which was well tolerated, TG dropped to 64 mmol/L. During 5-month follow-up there was a clear trend towards lower and stable TG values. CONCLUSION PEX is applicable in subjects with very low body weight when the extreme severity of the clinical picture has no therapeutic alternatives.
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Affiliation(s)
- Claudia Stefanutti
- Extracorporeal Therapeutic Unit, Immunohematology and Transfusion Medicine, Department of Molecular Medicine, University of Rome Sapienza, Umberto I' Hospital, 155, Viale del Policlinico, I-00161 Rome, Italy.
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Mendoza-Barberá E, Julve J, Nilsson SK, Lookene A, Martín-Campos JM, Roig R, Lechuga-Sancho AM, Sloan JH, Fuentes-Prior P, Blanco-Vaca F. Structural and functional analysis of APOA5 mutations identified in patients with severe hypertriglyceridemia. J Lipid Res 2013; 54:649-661. [PMID: 23307945 DOI: 10.1194/jlr.m031195] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
During the diagnosis of three unrelated patients with severe hypertriglyceridemia, three APOA5 mutations [p.(Ser232_Leu235)del, p.Leu253Pro, and p.Asp332ValfsX4] were found without evidence of concomitant LPL, APOC2, or GPIHBP1 mutations. The molecular mechanisms by which APOA5 mutations result in severe hypertriglyceridemia remain poorly understood, and the functional impairment/s induced by these specific mutations was not obvious. Therefore, we performed a thorough structural and functional analysis that included follow-up of patients and their closest relatives, measurement of apoA-V serum concentrations, and sequencing of the APOA5 gene in 200 nonhyperlipidemic controls. Further, we cloned, overexpressed, and purified both wild-type and mutant apoA-V variants and characterized their capacity to activate LPL. The interactions of recombinant wild-type and mutated apoA-V variants with liposomes of different composition, heparin, LRP1, sortilin, and SorLA/LR11 were also analyzed. Finally, to explore the possible structural consequences of these mutations, we developed a three-dimensional model of full-length, lipid-free human apoA-V. A complex, wide array of impairments was found in each of the three mutants, suggesting that the specific residues affected are critical structural determinants for apoA-V function in lipoprotein metabolism and, therefore, that these APOA5 mutations are a direct cause of hypertriglyceridemia.
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Affiliation(s)
| | - Josep Julve
- Institute for Biomedical Research (IIB) Sant Pau, 08025 Barcelona, Spain; CIBER de Diabetes y Enfermedades Metabólicas Asociadas, 08017 Barcelona, Spain
| | - Stefan K Nilsson
- Department of Medical Biosciences/Physiological Chemistry, Umeå University, SE90187, Sweden
| | - Aivar Lookene
- Department of Chemistry, Tallinn Technical University, Tallinn 12618, Estonia
| | | | - Rosa Roig
- Institute for Biomedical Research (IIB) Sant Pau, 08025 Barcelona, Spain
| | | | | | | | - Francisco Blanco-Vaca
- Institute for Biomedical Research (IIB) Sant Pau, 08025 Barcelona, Spain; CIBER de Diabetes y Enfermedades Metabólicas Asociadas, 08017 Barcelona, Spain; Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, 08025 Barcelona, Spain
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Fasano T, Zanoni P, Rabacchi C, Pisciotta L, Favari E, Adorni MP, Deegan PB, Park A, Hlaing T, Feher MD, Jones B, Uzak AS, Kardas F, Dardis A, Sechi A, Bembi B, Minuz P, Bertolini S, Bernini F, Calandra S. Novel mutations of ABCA1 transporter in patients with Tangier disease and familial HDL deficiency. Mol Genet Metab 2012; 107:534-41. [PMID: 22959828 DOI: 10.1016/j.ymgme.2012.08.005] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Revised: 08/06/2012] [Accepted: 08/06/2012] [Indexed: 11/24/2022]
Abstract
The objective of the study was the characterization of ABCA1 gene mutations in 10 patients with extremely low HDL-cholesterol. Five patients (aged 6 months to 76 years) presented with splenomegaly and thrombocytopenia suggesting the diagnosis of Tangier disease (TD). Three of them were homozygous for novel mutations either in intron (c.4465-34A>G) or in exons (c.4376delT and c.5449C>T), predicted to encode truncated proteins. One patient was compound heterozygous for a nucleotide insertion (c.1758_1759insG), resulting in a truncated protein and for a nucleotide substitution c.4799A>G, resulting in a missense mutation (p.H1600R). The last TD patient, found to be heterozygous for a known mutation (p.D1009Y), had a complete defect in ABCA1-mediated cholesterol efflux in fibroblasts, suggesting the presence of a second undetected mutant allele. Among the other patients, four were asymptomatic, but one, with multiple risk factors, had severe peripheral artery disease. Three of these patients were heterozygous for known mutations (p.R130K+p.N1800H, p.R1068C, p.N1800H), while two were carriers of novel mutations (c.1195-27G>A and c.396_397insA), predicted to encode truncated proteins. The pathogenic effect of the two intronic mutations (c. 1195-27G>A and c.4465-34A>G) was demonstrated by the analysis of the transcripts of splicing reporter mutant minigenes expressed in COS-1 cells. Both mutations activated an intronic acceptor splice site which resulted in a partial intron retention in mature mRNA with the production of truncated proteins. This study confirms the allelic heterogeneity of TD and suggests that the diagnosis of TD must be considered in patients with an unexplained splenomegaly, associated with thrombocytopenia and hypocholesterolemia.
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Affiliation(s)
- Tommaso Fasano
- Department of Biomedical Sciences, University of Modena and Reggio Emilia, Via Campi 287, Modena, Italy
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