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Rabbani B, Moghadam MA, Esmaeili S, Rabbani A, Akbari B, Mahdieh N. Pancreatitis as a Main Consequence of APOC2-Related Hypertriglyceridemia: The Role of Nonsense and Frameshift Variants. Int J Genomics 2024; 2024:6653857. [PMID: 38938447 PMCID: PMC11208794 DOI: 10.1155/2024/6653857] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2023] [Revised: 09/13/2023] [Accepted: 05/17/2024] [Indexed: 06/29/2024] Open
Abstract
APOC2-related hypertriglyceridemia occurs due to biallelic variants of this gene. Here, genotype-phenotype architecture of all pathogenic APOC2 variants is investigated among heterozygous and homozygous individuals. Clinical heterogeneity of various types of the variants is also described, and pancreatitis in more than half of homozygotes carrying chain-termination variants is highlighted as well. For this study, patients were selected who had a plasma triglyceride level above 250 mg/dL. The coding and intronic regions of the APOC2 gene were amplified using the Sanger sequencing to investigate the presence of variants. The genotypes, lipid profiles, and detailed clinical features were documented for all APOC2-related patients and heterozygous individuals. Pathogenicity of the variants was predicted and categorized using available bioinformatics tools such as MutationTaster and PolyPhen-2 and ACMG criteria. MetaDome and Phyre2 were applied for structural and functional in silico analyses. 40% (12 out of 30) of APOC2 variants were chain-termination (nonsense and frameshift) variants. These types of variants were determined in 60.53% of patients. 55% of these patients showed pancreatitis followed by lipemia retinalis (29%), abdominal pain (24%), hepatosplenomegaly (24%), and xanthomas (18%). The mean age of onset was about 22 years old. In at least 50% of 38 homozygous individuals, the TG level was more than 2000 mg/dL. More than 25% of heterozygous individuals showed at least one symptom. Pancreatitis and a severe form of HTG were found in 5 and 2% of heterozygous individuals, respectively. The main clinical features of APOC2-related hypertriglyceridemia include pancreatitis, lipemia retinalis, abdominal pain, hepatosplenomegaly, and xanthomas. Nonsense and frameshift homozygous variants usually lead to a severe form of hypertriglyceridemia. Pancreatitis is one of the main consequences of these types of mutations; thus, it is important to consider this point when evaluating asymptomatic individuals. Heterozygous individuals may become symptomatic due to the role of unknown modifying agent including environmental genetic factors.
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Affiliation(s)
- Bahareh Rabbani
- Growth and Development Research CenterTehran University of Medical Sciences, Tehran, Iran
| | - Mohadeseh Aghli Moghadam
- Department of GeneticsFaculty of SciencesShahid Chamran University of Ahvaz, Ahvaz, Iran
- Cardiogenetic Research CenterRajaie Cardiovascular Medical and Research CenterIran University of Medical Sciences, Tehran, Iran
| | - Shiva Esmaeili
- Growth and Development Research CenterTehran University of Medical Sciences, Tehran, Iran
| | - Amirhassan Rabbani
- Taleghani HospitalDepartment of Transplant & Hepatobiliary SurgeryShahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Bahman Akbari
- Department of Medical BiotechnologySchool of MedicineKermanshah University of Medical Sciences, Kermanshah, Iran
| | - Nejat Mahdieh
- Growth and Development Research CenterTehran University of Medical Sciences, Tehran, Iran
- Cardiogenetic Research CenterRajaie Cardiovascular Medical and Research CenterIran University of Medical Sciences, Tehran, Iran
- Physiology Research CenterIran University of Medical Sciences, Tehran, Iran
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Alves M, Laranjeira F, Correia-da-Silva G. Understanding Hypertriglyceridemia: Integrating Genetic Insights. Genes (Basel) 2024; 15:190. [PMID: 38397180 PMCID: PMC10887881 DOI: 10.3390/genes15020190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Revised: 01/24/2024] [Accepted: 01/25/2024] [Indexed: 02/25/2024] Open
Abstract
Hypertriglyceridemia is an exceptionally complex metabolic disorder characterized by elevated plasma triglycerides associated with an increased risk of acute pancreatitis and cardiovascular diseases such as coronary artery disease. Its phenotype expression is widely heterogeneous and heavily influenced by conditions as obesity, alcohol consumption, or metabolic syndromes. Looking into the genetic underpinnings of hypertriglyceridemia, this review focuses on the genetic variants in LPL, APOA5, APOC2, GPIHBP1 and LMF1 triglyceride-regulating genes reportedly associated with abnormal genetic transcription and the translation of proteins participating in triglyceride-rich lipoprotein metabolism. Hypertriglyceridemia resulting from such genetic abnormalities can be categorized as monogenic or polygenic. Monogenic hypertriglyceridemia, also known as familial chylomicronemia syndrome, is caused by homozygous or compound heterozygous pathogenic variants in the five canonical genes. Polygenic hypertriglyceridemia, also known as multifactorial chylomicronemia syndrome in extreme cases of hypertriglyceridemia, is caused by heterozygous pathogenic genetic variants with variable penetrance affecting the canonical genes, and a set of common non-pathogenic genetic variants (polymorphisms, using the former nomenclature) with well-established association with elevated triglyceride levels. We further address recent progress in triglyceride-lowering treatments. Understanding the genetic basis of hypertriglyceridemia opens new translational opportunities in the scope of genetic screening and the development of novel therapies.
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Affiliation(s)
- Mara Alves
- Faculty of Pharmacy, University of Porto, 4050-313 Porto, Portugal;
| | - Francisco Laranjeira
- CGM—Centro de Genética Médica Jacinto de Magalhães, Centro Hospitalar Universitário de Santo António (CHUdSA), 4099-028 Porto, Portugal;
- UMIB—Unit for Multidisciplinary Research in Biomedicine, ICBAS—School of Medicine and Biomedical Sciences, University of Porto, 4050-346 Porto, Portugal
- ITR—Laboratory for Integrative and Translational Research in Population Health, 4050-600 Porto, Portugal
| | - Georgina Correia-da-Silva
- UCIBIO Applied Molecular Biosciences Unit and Associate Laboratory i4HB—Institute for Health and Bioeconomy Laboratory of Biochemistry, Department of Biological Sciences, Faculty of Pharmacy, University of Porto, 4050-313 Porto, Portugal
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Abstract
PURPOSE OF REVIEW Novel therapies for severe dyslipidemia target a wide range of unmet medical needs: severe familial hypercholesterolemia, severe hypertriglyceridemia and chylomicronemia, elevated lipoprotein (a), lipodystrophies, high-density lipoprotein particle diseases, lysosomal acid lipase deficiency and storage diseases, nonalcoholic fatty liver disease and others. The purpose of this review is to describe the contribution of human genetics to the development of therapeutic approaches targeting severe dyslipidemia. RECENT FINDINGS Recent advances in human genetics and the identification of rare genetic variants having strong effects on disease risk not only accelerated the development of therapies for severe dyslipidemia, they also revealed new pathways, genes and mechanisms of health, disease or drug response, and facilitated molecular diagnosis, which may prove essential as the authorized use of some of these novel drugs is limited to specific conditions. In addition, the dissection of the gene and cell machinery gave rise to new technologies, gene-based therapies and biodrugs covering a broad range of novel agents currently available or in clinical development to treat severe lipid disorders. SUMMARY Several novel therapies are recently available or under development to treat severe dyslipidemia and associated risk stem directly from genetic research. Altogether, these therapies target a broad variety of severe dyslipidemia pathways or mechanisms and illustrate that clinical lipidology has now entered the era of precision medicine.
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Affiliation(s)
- Daniel Gaudet
- Department of Medicine, Lipidology Unit, Community Genomic Medicine Center, Université de Montréal and ECOGENE-21 Clinical and Translational Research Center, Chicoutimi, Quebec, Canada
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Jiang J, Wang Y, Ling Y, Kayoumu A, Liu G, Gao X. A novel APOC2 gene mutation identified in a Chinese patient with severe hypertriglyceridemia and recurrent pancreatitis. Lipids Health Dis 2016; 15:12. [PMID: 26772541 PMCID: PMC4715280 DOI: 10.1186/s12944-015-0171-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Accepted: 12/29/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The severe forms of hypertriglyceridemia are usually caused by genetic defects. In this study, we described a Chinese female with severe hypertriglyceridemia caused by a novel homozygous mutation in the APOC2 gene. METHODS Lipid profiles of the pedigree were studied in detail. LPL and HL activity were also measured. The coding regions of 5 candidate genes (namely LPL, APOC2, APOA5, LMF1, and GPIHBP1) were sequenced using genomic DNA from peripheral leucocytes. The ApoE gene was also genotyped. RESULTS Serum triglyceride level was extremely high in the proband, compared with other family members. Plasma LPL activity was also significantly reduced in the proband. Serum ApoCII was very low in the proband as well as in the heterozygous mutation carriers. A novel mutation (c.86A > CC) was identified on exon 3 [corrected] of the APOC2 gene, which converted the Asp [corrected] codon at position 29 into Ala, followed by a termination codon (TGA). CONCLUSIONS This study presented the first case of ApoCII deficiency in the Chinese population, with a novel mutation c.86A > CC in the APOC2 gene identified. Serum ApoCII protein might be a useful screening test for identifying mutation carriers.
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Affiliation(s)
- Jingjing Jiang
- Department of Endocrinology and Metabolism, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Yuhui Wang
- Institute of Cardiovascular Science, Peking University and Key laborotory of Molecular Cardiovascular Science, Ministry of Education, Beijing, China
| | - Yan Ling
- Department of Endocrinology and Metabolism, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Abudurexiti Kayoumu
- Institute of Cardiovascular Science, Peking University and Key laborotory of Molecular Cardiovascular Science, Ministry of Education, Beijing, China
| | - George Liu
- Institute of Cardiovascular Science, Peking University and Key laborotory of Molecular Cardiovascular Science, Ministry of Education, Beijing, China
| | - Xin Gao
- Department of Endocrinology and Metabolism, Zhongshan Hospital, Fudan University, Shanghai, China.
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5
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Brunham LR, Hayden MR. Human genetics of HDL: Insight into particle metabolism and function. Prog Lipid Res 2015; 58:14-25. [DOI: 10.1016/j.plipres.2015.01.001] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Revised: 12/22/2014] [Accepted: 01/07/2015] [Indexed: 10/24/2022]
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Okubo M, Toromanovic A, Ebara T, Murase T. Apolipoprotein C-II Tuzla: A novel large deletion in APOC2 caused by Alu-Alu homologous recombination in an infant with apolipoprotein C-II deficiency. Clin Chim Acta 2015; 438:148-53. [DOI: 10.1016/j.cca.2014.08.022] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2014] [Accepted: 08/19/2014] [Indexed: 11/24/2022]
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Chokshi N, Blumenschein SD, Ahmad Z, Garg A. Genotype-phenotype relationships in patients with type I hyperlipoproteinemia. J Clin Lipidol 2014; 8:287-95. [PMID: 24793350 DOI: 10.1016/j.jacl.2014.02.006] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Revised: 01/07/2014] [Accepted: 02/12/2014] [Indexed: 12/17/2022]
Abstract
CONTEXT Type I hyperlipoproteinemia (T1HLP) is a rare, autosomal recessive disorder characterized by extreme hypertriglyceridemia that fails to respond to lipid-lowering agents, predisposing to frequent attacks of acute pancreatitis. Mutations in lipoprotein lipase (LPL), apolipoprotein CII (APOC2), lipase maturation factor 1 (LMF1), glycosyl-phosphatidylinositol anchored high-density lipoprotein-binding protein 1 (GPIHBP1), and apolipoprotein AV (APOA5) cause T1HLP, but we lack data on phenotypic variations among the different genetic subtypes. OBJECTIVE To study genotype-phenotype relationships among subtypes of T1HLP patients. DESIGN/INTERVENTION Genetic screening for mutations in LPL, APOC2, GPIHBP1, LMF1, and APOA5. SETTING Tertiary referral center. PATIENTS Ten patients (7 female, 3 male) with chylomicronemia, serum triglyceride levels about 2000 mg/dL, and no secondary causes of hypertriglyceridemia. MAIN OUTCOME MEASURES Genotyping and phenotypic features. RESULTS Four patients harbored homozygous or compound heterozygous mutations in LPL, 3 had homozygous mutations in GPIHBP1, and 1 had a heterozygous APOA5 mutation. We failed to fully identify the genetic etiology in 2 cases: 1 had a heterozygous LPL mutation only and another did not have any mutations. We identified 2 interesting phenotypic features: the patient with heterozygous APOA5 mutation normalized triglyceride levels with weight loss and fish oil therapy, and all 7 female patients were anemic. CONCLUSIONS Our data suggest the possibility of novel loci for T1HLP. We observed that heterozygous APOA5 mutation can cause T1HLP but such patients may unexpectedly respond to therapy, and females with T1HLP suffer from anemia. Further studies of larger cohorts may elucidate more phenotype-genotypes relationships among T1HLP subtypes.
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Affiliation(s)
- Neema Chokshi
- Division of Nutrition and Metabolic Diseases, Department of Internal Medicine, Center for Human Nutrition
| | - Sarah D Blumenschein
- Department of Pediatrics, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390
| | - Zahid Ahmad
- Division of Nutrition and Metabolic Diseases, Department of Internal Medicine, Center for Human Nutrition
| | - Abhimanyu Garg
- Division of Nutrition and Metabolic Diseases, Department of Internal Medicine, Center for Human Nutrition.
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9
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Takase S, Osuga JI, Fujita H, Hara K, Sekiya M, Igarashi M, Takanashi M, Takeuchi Y, Izumida Y, Ohta K, Kumagai M, Nishi M, Kubota M, Masuda Y, Taira Y, Okazaki S, Iizuka Y, Yahagi N, Ohashi K, Yoshida H, Yanai H, Tada N, Gotoda T, Ishibashi S, Kadowaki T, Okazaki H. Apolipoprotein C-II Deficiency with No Rare Variant in the APOC2 Gene. J Atheroscler Thromb 2013; 20:481-93. [DOI: 10.5551/jat.16592] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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Kei AA, Filippatos TD, Tsimihodimos V, Elisaf MS. A review of the role of apolipoprotein C-II in lipoprotein metabolism and cardiovascular disease. Metabolism 2012; 61:906-21. [PMID: 22304839 DOI: 10.1016/j.metabol.2011.12.002] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2011] [Revised: 12/06/2011] [Accepted: 12/08/2011] [Indexed: 12/21/2022]
Abstract
The focus of this review is on the role of apolipoprotein C-II (apoC-II) in lipoprotein metabolism and the potential effects on the risk of cardiovascular disease (CVD). We searched PubMed/Scopus for articles regarding apoC-II and its role in lipoprotein metabolism and the risk of CVD. Apolipoprotein C-II is a constituent of chylomicrons, very low-density lipoprotein, low-density lipoprotein, and high-density lipoprotein (HDL). Apolipoprotein C-II contains 3 amphipathic α-helices. The lipid-binding domain of apoC-II is located in the N-terminal, whereas the C-terminal helix of apoC-II is responsible for the interaction with lipoprotein lipase (LPL). At intermediate concentrations (approximately 4 mg/dL) and in normolipidemic subjects, apoC-II activates LPL. In contrast, both an excess and a deficiency of apoC-II are associated with reduced LPL activity and hypertriglyceridemia. Furthermore, excess apoC-II has been associated with increased triglyceride-rich particles and alterations in HDL particle distribution, factors that may increase the risk of CVD. However, there is not enough current evidence to clarify whether increased apoC-II causes hypertriglyceridemia or is an epiphenomenon reflecting hypertriglyceridemia. A number of pharmaceutical interventions, including statins, fibrates, ezetimibe, nicotinic acid, and orlistat, have been shown to reduce the increased apoC-II concentrations. An excess of apoC-II is associated with increased triglyceride-rich particles and alterations in HDL particle distribution. However, prospective trials are needed to assess if apoC-II is a CVD marker or a risk factor in high-risk patients.
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Affiliation(s)
- Anastazia A Kei
- Department of Internal Medicine, School of Medicine, University of Ioannina, 45 110 Ioannina, Greece
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11
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Takahashi M, Saibara T, Nemoto Y, Ono M, Akisawa N, Iwasaki S, Toda K, Ogawa Y, Wakatsuki A, Inagaki S, Onishi S. A novel type hypertriglyceridemia observed in FLS mice. Lipids 2003; 38:687-92. [PMID: 14506831 DOI: 10.1007/s11745-003-1116-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
The unique inborn hypertriglyceridemia seen in FLS (fatty liver Shionogi) mice was relieved by the administration of purified apolipoprotein (apo) C-II. Lipoprotein lipase (LPL) and its cofactor, apoC-II, play a pivotal role in VLDL metabolism. Therefore, we investigated the genetic background involved in this hypertriglyceridemia. Plasma levels of TG and total cholesterol as well as LPL activity were measured in male FLS mice and C57/BL6J mice. Agarose gel electrophoresis and fast protein liquid chromatography were used to analyze the lipoprotein profile. A cross experiment was done to determine the genetic background of hypertriglyceridemia observed in FLS mice. cDNA sequences of apoC-II and apoC-III of FLS mice were determined. Prealpha-lipoprotein was the predominant lipoprotein class in FLS mouse plasma. LPL activity remained in the range observed in C57/BL6J mice, and purified apoC-II transiently relieved FLS mice from hypertriglyceridemia. Prealpha-lipoproteinemia was inherited in an autosomal recessive manner. ApoC-III appeared to be a causal factor for this unique hypertriglyceridemia. Microsatellite analysis, however, revealed that the responsible chromosome was not 7; rather, apoC-III mapped onto chromosome 9. Therefore, we suggest apoC-III as a candidate causative factor for the hypertriglyceridemia observed in FLS mice because an excessive amount of apoC-III attenuates LPL activity in vivo and in vitro.
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Affiliation(s)
- Masaya Takahashi
- Department of Gastroenterology and Hepatology, Kochi Medical School, Nankoku 783-8505, Japan
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Wilson CJ, Priore Oliva C, Maggi F, Catapano AL, Calandra S. Apolipoprotein C-II deficiency presenting as a lipid encephalopathy in infancy. Ann Neurol 2003; 53:807-10. [PMID: 12783430 DOI: 10.1002/ana.10598] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
An infant presented with massive hyperchylomicronemia and a severe encephalopathy. MRI showed marked lipid deposition throughout the brain. Despite the normalization of the biochemistry, there was little clinical improvement, and at 18 months of age she has severe developmental delay, a strikingly abnormal MRI. Apolipoprotein C-II, the lipoprotein on chylomicrons responsible for the activation of lipoprotein lipase, was not detectable in blood. Analysis of the APO C-II gene revealed a novel homozygous point mutation, 1118C-->A. Subsequently, another sibling has been born with the same homozygous mutation and similar biochemistry but, perhaps because of early treatment, a normal neurological outcome.
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Affiliation(s)
- Callum J Wilson
- Metabolic Service, Starship Children's Hospital, Auckland, New Zealand.
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13
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Vorechovský I, Luo L, Hertz JM, Frøland SS, Klemola T, Fiorini M, Quinti I, Paganelli R, Ozsahin H, Hammarström L, Webster AD, Smith CI. Mutation pattern in the Bruton's tyrosine kinase gene in 26 unrelated patients with X-linked agammaglobulinemia. Hum Mutat 2000; 9:418-25. [PMID: 9143921 DOI: 10.1002/(sici)1098-1004(1997)9:5<418::aid-humu7>3.0.co;2-#] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Mutation pattern was characterized in the Bruton's tyrosine kinase gene (BTK) in 26 patients with X-linked agammaglobulinemia, the first described immunoglobulin deficiency, and was related to BTK expression. A total of 24 different mutations were identified. Most BTK mutations were found to result in premature termination of the translation product. Mutations were detected in most BTK exons with a predominance of frameshift and nonsense mutations in the 5' end of the gene and missense mutations in its 3' part, corresponding to the catalytic domain of the enzyme. Nonsense and frameshift mutations were associated with diminished levels of BTK mRNA expression, except for a frameshift mutation in exon 17 and two nonsense mutations in exon 2, indicating that these cases are not confined to penultimate exons. One amino acid substitution (R28H) was found in the pleckstrin homology domain's residue, which is mutated in mice bearing the X-linked immunodeficiency phenotype; another substitution (R307G) was identified in the src homology domain 2. All remaining amino acid substitutions were found in the catalytic domain of Btk.
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Affiliation(s)
- I Vorechovský
- Karolinska Institute, Department of Biosciences, NOVUM, Huddinge, Sweden
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15
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Jong MC, Hofker MH, Havekes LM. Role of ApoCs in lipoprotein metabolism: functional differences between ApoC1, ApoC2, and ApoC3. Arterioscler Thromb Vasc Biol 1999; 19:472-84. [PMID: 10073946 DOI: 10.1161/01.atv.19.3.472] [Citation(s) in RCA: 369] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- M C Jong
- TNO-Prevention and Health, Gaubius Laboratory, MGC-Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands.
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16
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Abstract
The chylomicronemia syndrome is a disorder characterized by severe hypertriglyceridemia and fasting chylomicronemia. Genetic causes of the syndrome are rare and include deficiency of lipoprotein lipase (LPL), apolipoprotein C-II, and familial inhibitor of LPL. Patients with familial forms of hypertriglyceridemia in combination with secondary acquired disorders account for most individuals presenting with chylomicronemia. The clinical manifestations--lipid and other biochemical abnormalities--as well as treatment options for chylomicronemic patients are discussed.
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Affiliation(s)
- S Santamarina-Fojo
- Section of Molecular Biology, Molecular Disease Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
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17
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Hoffmeyer S, Nürnberg P, Ritter H, Fahsold R, Leistner W, Kaufmann D, Krone W. Nearby stop codons in exons of the neurofibromatosis type 1 gene are disparate splice effectors. Am J Hum Genet 1998; 62:269-77. [PMID: 9463322 PMCID: PMC1376891 DOI: 10.1086/301715] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Stop mutations are known to disrupt gene function in different ways. They both give rise to truncated polypeptides because of the premature-termination codons (PTCs) and frequently affect the metabolism of the corresponding mRNAs. The analysis of neurofibromin transcripts from different neurofibromatosis type 1 (NF1) patients revealed the skipping of exons containing PTCs. The phenomenon of exon skipping induced by nonsense mutations has been described for other disease genes, including the CFTR (cystic fibrosis transmembrance conductance regulator) gene and the fibrillin gene. We characterized several stop mutations localized within a few base pairs in exons 7 and 37 and noticed complete skipping of either exon in some cases. Because skipping of exon 7 and of exon 37 does not lead to a frameshift, PTCs are avoided in that way. Nuclear-scanning mechanisms for PTCs have been postulated to trigger the removal of the affected exons from the transcript. However, other stop mutations that we found in either NF1 exon did not lead to a skip, although they were localized within the same region. Calculations of minimum-free-energy structures of the respective regions suggest that both changes in the secondary structure of the mRNA and creation or disruption of exonic sequences relevant for the splicing process might in fact cause these different splice phenomena observed in the NF1 gene.
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Affiliation(s)
- S Hoffmeyer
- Abteilung Humangenetik, Universitat Ulm, Ulm, Germany.
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18
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Streicher R, Geisel J, Weisshaar C, Avci H, Oette K, Müller-Wieland D, Krone W. A single nucleotide substitution in the promoter region of the apolipoprotein C-II gene identified in individuals with chylomicronemia. J Lipid Res 1996. [DOI: 10.1016/s0022-2275(20)37463-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Wang CS, Downs D, Dashti A, Jackson KW. Isolation and characterization of recombinant human apolipoprotein C-II expressed in Escherichia coli. BIOCHIMICA ET BIOPHYSICA ACTA 1996; 1302:224-30. [PMID: 8765143 DOI: 10.1016/0005-2760(96)00065-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
A full-length recombinant human apolipoprotein C-II (ApoC-II) has been successfully expressed in Escherichia coli using the T7 expression system. The recombinant ApoC-II. which was expressed intracellularly in the inclusion bodies, was solubilized with 8 M urea and purified using Sephadex G-75 gel permeation chromatography. Four liters of the bacterial culture yielded 16-20 mg of purified recombinant ApoC-II. Sequencing and mass spectrometric analyses indicated that the isolated recombinant ApoC-II contained predominantly (64%) the native form with threonine as the N-terminus, but also contained a minor (36%) molecular form of ApoC-II with an additional methionine at the N-terminus (Met-ApoC-II). Analysis of the recombinant ApoC-II by tryptic digestion and high performance liquid chromatography-electrospray mass spectrometry provides additional conclusive evidence that, with the exception of the N-terminus of Met-ApoC-II, the expressed ApoC-II has the expected peptide sequence. However, this extra N-terminal methionine residue can be excised by further in vitro treatment with methionine aminopeptidase. The purified recombinant ApoC-II was found to be competent in the activation of bovine milk lipoprotein lipase. Thus, the recombinant ApoC-II prepared from E. coli may have a pharmacological application for the treatment of patients with genetic hypertriglyceridemia caused by ApoC-II deficiency.
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Affiliation(s)
- C S Wang
- Protein Studies Program, Oklahoma Medical Research Foundation, Oklahoma City 73104, USA.
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20
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Wiebusch H, Nofer JR, von Eckardstein A, Funke H, Wahrburg U, Martin H, Köhler E, Assmann G. Electrophoretic screening for human apolipoprotein C-II variants: repeated identification of apolipoprotein C-II(K19T). J Mol Med (Berl) 1995; 73:373-8. [PMID: 8520970 DOI: 10.1007/bf00192889] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Screening for apolipoprotein (apo) C-II variants in the plasma of 400 students, 600 patients of a cardiological rehabilitation center, and 1200 patients of an outpatient lipid clinic by isoelectric focusing and subsequent anti-apo C-II immunoblotting led to the identification of four individuals whose plasma samples contained an apo C-II isoform with an abnormal isoelectric point. In all cases direct sequencing of PCR-amplified DNA assessed a heterozygous A to C transversion in codon 19 of the apo C-II gene which leads to the replacement of lysine with threonine. Two of the four index patients presented with moderate hypertriglyceridemia; one suffered from severe hyperlipidemia, with triglyceride levels ranging between 180 and 1900 mg/dl, depending on dietary changes. Sequencing of this proband's lipoprotein lipase gene showed no alteration compared to the wild-type sequence. A study in his family revealed that heterozygosity for apo C-II(K19T) is not associated with differences in mean lipid and lipoprotein concentrations. In conclusion, apo C-II(K19T) occurs in Germany at a frequency of approximately 1 in 550. Although this variant is not sufficient to cause hypertriglyceridemia, it may be possible that apo C-II(K19T) cause hypertriglyceridemia in the presence of additional as yet unidentified environmental and/or genetic factors.
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Affiliation(s)
- H Wiebusch
- Institut für Arterioskleroseforschung, Universität Münster, Germany
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21
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Yoshida K, Furihata K, Takeda S, Nakamura A, Yamamoto K, Morita H, Hiyamuta S, Ikeda S, Shimizu N, Yanagisawa N. A mutation in the ceruloplasmin gene is associated with systemic hemosiderosis in humans. Nat Genet 1995; 9:267-72. [PMID: 7539672 DOI: 10.1038/ng0395-267] [Citation(s) in RCA: 345] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
We identified a mutation in the ceruloplasmin (Cp) gene in a Japanese family with aceruloplasminemia, some of whose members showed extrapyramidal disorders, cerebellar ataxia, and diabetes mellitus. A post-mortem study of the proband revealed excessive iron deposition mainly in the brain, liver and pancreas. The G to A transition at the splice acceptor site introduces a premature termination codon at the amino acid position 991 by defective splicing, thereby truncating the carboxyl terminus of Cp in affected individuals. We conclude that the mutation in the Cp gene is associated with systemic hemosiderosis in humans.
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Affiliation(s)
- K Yoshida
- Department of Medicine (Neurology), Shinshu University School of Medicine, Matsumoto, Japan
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22
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Boles DJ, Proia RL. The molecular basis of HEXA mRNA deficiency caused by the most common Tay-Sachs disease mutation. Am J Hum Genet 1995; 56:716-24. [PMID: 7887427 PMCID: PMC1801160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Tay-Sachs disease (TSD) is a catastrophic neurodegenerative disorder caused by mutations in the HEXA gene. The most common TSD allele worldwide contains a 4-bp insertion in exon 11 that produces a downstream premature termination codon. Despite normal transcription of this allele, HEXA mRNA is severely reduced, indicating that the HEXA transcript must be unstable. Minigenes of HEXA were constructed and expressed in mouse L cells, to investigate the relationship between the 4-bp insertion and mRNA deficiency. We conclude that the mRNA instability is caused by the premature termination codon and not by a cryptic mutation or by the 4-bp insertion directly and that degradation occurs coincident with or after splicing.
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Affiliation(s)
- D J Boles
- Section on Biochemical Genetics, National Institutes of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda 20892-1810
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23
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Affiliation(s)
- M J Halpern
- Instituto Superior de Ciências da Saúde-Sul, Quinta da Granja, Monte de Caparica, Portugal
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24
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Tuzgöl S, Bijvoet SM, Bruin T, Kastelein JJ, Hayden MR. Apolipoprotein CII-Padova (Tyr37-->stop) as a cause of chylomicronaemia in an Italian kindred from Siculiana. J Med Genet 1994; 31:622-6. [PMID: 7815420 PMCID: PMC1050024 DOI: 10.1136/jmg.31.8.622] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
In this paper we report on the molecular defect underlying apolipoprotein CII (apoCII) deficiency in an Italian kindred. ApoCII serves as cofactor for lipoprotein lipase (LPL) in triglyceride hydrolysis of chylomicrons and very low density lipoproteins. Homozygous apoCII deficiency manifests with type I hyperlipoproteinaemia and is a rare disorder of lipoprotein metabolism. Until now, only 10 kindreds with apoCII deficiency have been published and all underlying mutations were unique. The proband was the offspring of a consanguineous mating. Sequencing of cloned DNA from the proband presented in this report showed homozygosity for a C-->A substitution at position 3002 in the apoCII gene, resulting in the introduction of a premature stop codon at residue 37 of the mature apoCII protein. Therefore, a truncated apoCII is synthesised, lacking the part of the apolipoprotein that activates LPL. This mutation has previously been described in another Italian family and is known as apoCIIPadova. We propose that apoCIIPadova is a frequent cause of apoCII deficiency in persons of Italian descent.
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Affiliation(s)
- S Tuzgöl
- Centre for Vascular Medicine, Academic Medical Centre, Amsterdam, The Netherlands
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25
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Shoshani T, Kerem E, Szeinberg A, Augarten A, Yahav Y, Cohen D, Rivlin J, Tal A, Kerem B. Similar levels of mRNA from the W1282X and the delta F508 cystic fibrosis alleles, in nasal epithelial cells. J Clin Invest 1994; 93:1502-7. [PMID: 7512981 PMCID: PMC294164 DOI: 10.1172/jci117128] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The effect of nonsense mutations on mRNA levels is variable. The levels of some mRNAs are not affected and truncated proteins are produced, while the levels of others are severely decreased and null phenotypes are observed. The effect on mRNA levels is important for the understanding of phenotype-genotype association. Cystic fibrosis (CF) is a lethal autosomal recessive disease with variable clinical presentation. Recently, two CF patients with mild pulmonary disease carrying nonsense mutations (R553X, W1316X) were found to have severe deficiency of mRNA. In the Jewish Ashkenazi CF patient population, 60% of the chromosomes carry a nonsense mutation, W1282X. Patients homozygous for this mutation have severe disease presentation with variable pulmonary disease. The presence of CF transcripts in a group of patients homozygous and heterozygous for this mutation was studied by reverse transcriptase PCR of various regions of the gene. Subsequent hybridization to specific CF PCR probes and densitometry analysis indicated that the CF mRNA levels in patients homozygous for the W1282X mutation are not significantly decreased by the mutation. mRNA levels were compared for patients heterozygous for the W1282X mutation. The relative levels of mRNA with the W1282X, and the delta F508 or the normal alleles, were similar in each patient. These results indicate that the severe clinical phenotype of patients carrying the W1282X mutation is not due to a severe deficiency of mRNA. In addition, the severity, progression, and variability of the pulmonary disease are affected by other, as yet unknown factors.
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Affiliation(s)
- T Shoshani
- Department of Genetics, Hebrew University of Jerusalem, Israel
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26
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Zanelli T, Catapano AL, Averna MR, Barbagallo CM, Liotta A, Giardina FC, Notarbartolo A. A new case of apo C-II deficiency with a nonsense mutation in the apo C-II gene. Clin Chim Acta 1994; 224:111-8. [PMID: 8004780 DOI: 10.1016/0009-8981(94)90176-7] [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: 01/28/2023]
Abstract
The apo C-II gene from a patient with apo C-II deficiency has been sequenced after amplification by the polymerase chain reaction (PCR). The sequence analysis revealed a substitution of adenosine for cytosine at position 3,002 in exon 3, leading to the introduction of a premature stop codon (TAA) at a position corresponding to aminoacid 37 of mature apo C-II. This mutation creates a new Rsa I restriction enzyme site in the apo C-II gene. Amplification of DNA from family members by PCR and digestion with Rsa I established that the patient is a true homozygote for this mutation. The same nucleotide has been substituted for the mutation apo C-IIPadova and apo C-IIBari previously described in two kindreds from Italy. From these data we speculate that base pair 3,002 in the apo C-II gene may represent a hot spot for mutation.
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Affiliation(s)
- T Zanelli
- Istituto di Scienze Farmacologiche, Università di Milano, Italy
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27
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28
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Rolfini R, Cabrini G. Nonsense mutation R1162X of the cystic fibrosis transmembrane conductance regulator gene does not reduce messenger RNA expression in nasal epithelial tissue. J Clin Invest 1993; 92:2683-7. [PMID: 7504691 PMCID: PMC288466 DOI: 10.1172/jci116885] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Cystic fibrosis (CF) patients bearing the premature translation termination mutation (nonsense mutation) W1282X present severe pulmonary and pancreatic disease, whereas patients carrying other nonsense mutations such as G542X, R553X, S1255X, R1162X, and W1316X show a severe pancreatic but mild pulmonary illness. CF gene expression was found absent in respiratory tissues with mutations R553X and W1316X, which led to the hypothesis that the absence of the gene product in the lung is more favorable than the presence of an altered one. We asked whether or not all the nonsense mutations characterized by mild pulmonary disease phenotypes do present the absence of CF gene expression. We therefore investigated gene expression at the mRNA level in respiratory cells obtained from nasal polyps from a patient homozygous for the R1162X mutation. Gene expression was studied by amplification with polymerase chain reaction of segments of the CF transmembrane conductance regulator cDNA that was obtained by reverse transcription of RNA. Semiquantitative analysis was performed by Northern analysis. By comparing the data obtained from polyps deriving from non-CF subjects and a CF patient homozygous for dF508 mutation, it is shown that no reduction of CF gene expression is evident in R1162X respiratory tissue. We conclude that CF nonsense mutations have heterogeneous mechanisms of gene expression.
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Affiliation(s)
- R Rolfini
- Cystic Fibrosis Center, Ospedale Civile Maggiore, Verona, Italy
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29
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Gabelli C, Bilato C, Santamarina-Fojo S, Martini S, Brewer HB, Crepaldi G, Baggio G. Heterozygous apolipoprotein C-II deficiency: lipoprotein and apoprotein phenotype and RsaI restriction enzyme polymorphism in the Apo C-IIPadova kindred. Eur J Clin Invest 1993; 23:522-8. [PMID: 7902280 DOI: 10.1111/j.1365-2362.1993.tb00960.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Deficiency of apolipoprotein C-II (apo C-II), the cofactor for lipoprotein lipase, results in the familial chylomicronaemia syndrome characterized by severe hypertriglyceridaemia and fasting chylomicronaemia. To investigate the biochemical features of the heterozygous state for apo C-II deficiency, we characterized the lipid, lipoprotein and apolipoprotein profiles in 18 relatives of two affected individuals (brother and sister) homozygous for the apo C-IIPadova gene defect which results in the synthesis of a truncated 36 amino acid apolipoprotein. Carrier status was established in first degree relatives as well as in seven non-obligate heterozygotes by restriction enzyme analysis of amplified apo C-II genomic DNA using RsaI. No significant differences in lipid, lipoprotein and apo C-II levels were observed in heterozygotes when compared to unaffected family members. Thus, in this study, the carrier state was not associated with hypertriglyceridaemia or reduced plasma levels of apo C-II. However, analysis of amplified DNA from members of the apo C-IIPadova kindred by digestion with the enzyme RsaI, which identifies the mutant apo C-II, permitted the identification of heterozygous family members which could not be recognized by measuring either fasting triglycerides or plasma apo C-II levels. This study provides further evidence that apo C-II deficiency syndrome is a heterogeneous disease not only at the molecular level but also on the clinical ground with variable phenotypic expression in heterozygous individuals from different kindreds.
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Affiliation(s)
- C Gabelli
- Department of Internal Medicine, University of Padova, Italy
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30
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Abstract
Gene mutations affecting mRNA processing and translation are not common causes of human genetic disease. Their analysis has nevertheless provided important insights into the basic biochemical mechanisms underlying mRNA transcription and translation.
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Affiliation(s)
- D N Cooper
- Charter Molecular Genetics Laboratory, Thrombosis Research Institute, London, U.K
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31
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Lipoprotein lipase release from BFC-1 beta adipocytes. Effects of triglyceride-rich lipoproteins and lipolysis products. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)42165-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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32
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Abstract
Hypertriglyceridaemia, as defined by fasting triglyceride levels of greater than 2.8 mmol l-1, is a prevalent dyslipoproteinaemia in our population. The underlying pathophysiological mechanisms that result in elevations of plasma triglycerides are heterogeneous and, in most cases, incompletely understood. However, in a subset of patients presenting with this lipid disorder, the biochemical and genetic defects that lead to hypertriglyceridaemia have been well characterized. These individuals present with the familial chylomicronaemia syndrome, a rare genetic disorder that is inherited as an autosomal recessive trait, and is characterized by severe fasting hypertriglyceridaemia, massive accumulations of chylomicrons in plasma, and recurrent bouts of pancreatitis. The two major causes of the familial chylomicronaemia syndrome are a deficiency of the enzyme, lipoprotein lipase (LPL), or its cofactor, apolipoprotein (apo) C-II. Together, these two proteins initiate the hydrolysis of triglycerides present in chylomicrons and very low density lipoproteins. In the past decade our understanding of the underlying molecular defects that lead to familial chylomicronaemia has been greatly enhanced by the identification of mutations in the genes for LPL and apoC-II. Characterization of these defects has provided new insights into the structure and function of apoC-II and LPL and established the important role that these two proteins play in normal triglyceride metabolism.
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Affiliation(s)
- S S Fojo
- Molecular Disease Branch, National Heart, Lung and Blood Institute, National Institute of Health, Bethesda, MD
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33
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Capurso A, Resta F, Turturro F, Colacicco AM, Crecchio C, Pepe G. Apo C-II deficiency type bari. Eur J Epidemiol 1992; 8 Suppl 1:64-70. [PMID: 1354624 DOI: 10.1007/bf00145352] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
We formerly studied an Italian family with apo C-II deficiency. Two probands were homozygous for the defect (unmeasurable circulating apolipoprotein C-II and absence of C-II bands on immunoelectrophoresis). We documented the synthesis of the protein at the intestinal level in the probands with immunohistological techniques. With the purpose of investigating the molecular basis of the defect, Southern analysis, polymerase chain reaction (PCR) amplification and sequence analysis were carried out on one of the two cases. We identified a point mutation C to G transversion in the third exon of the gene causing a premature stop codon. Our hypothesis is that the truncated protein of 36 aa., instead of 79 aa., lacks its functional domain. This causes inefficiency in the activation of lipoprotein lipase (LPL) and the instability of the circulating molecule, which could have an higher catabolic rate compared to a normal protein. The faster disappearance from the circulating compartment make it unmeasurable. The mutation destroys a Rsa I site, present in the normal gene sequence. We suggest the use of this site for a rapid Restriction Fragment Length Polymorphism (RFLP) on PCR amplification products to screen this defect in the Italian population.
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Affiliation(s)
- A Capurso
- Chair of Geriatrics, University of Bari Medical School, Italy
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34
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Menke-Möllers I, Kurth J, Oette K. Studies on an apolipoprotein C-II variant occurring in Caucasians. Electrophoresis 1992; 13:244-51. [PMID: 1628605 DOI: 10.1002/elps.1150130150] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Apolipoproteins C (apo C-II, apo C-III0, apo C-III1 and apo C-III2) from delipidated very low density lipoproteins (VLDL) of 522 normo- and hyperlipoproteinemic Caucasians were screened by analytical isoelectric focusing. The immobilized pH gradient used was pH 4.0-5.0 with 7 M urea, which raised the apparent pH range to 4.8-5.7. As identified by immunoblotting, six unrelated persons had two major isoforms of apo C-II, the normal apo C-II-1 (which focuses between apo C-III0 and apo C-III1) and a variant, designated apo C-II-v according to Huff et al., focusing between apo C-III1 and apo C-III2 due to a more acidic pI. In narrow pH gradients, apo C-II-v can readily be discriminated from the minor isoform, apo C-II-2, due to its slightly more basic pI, corresponding to a difference of 0.01 pH units. Neuraminidase treatment did not alter the pI of apo C-II-v and on two-dimensional electrophoresis the molecular weights of apo C-II-1 and apo C-II-v were indistinguishable. The frequency of apo C-II-v was 1.2%. It was the same in males and females and was independent of hypertriglyceridemia. The autosomal codominant inheritance could be demonstrated in the pedigree of one family. Electroblotting of apo C-II-1 and apo C-II-v onto activated glass fiber sheets, followed by amino acid sequence analysis of the amino terminal ends, revealed an exchange of the amino acid lysine at position 19 by threonine in apo C-II-v.(ABSTRACT TRUNCATED AT 250 WORDS)
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35
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Parrott CL, Alsayed N, Rebourcet R, Santamarina-Fojo S. ApoC-IIParis2: a premature termination mutation in the signal peptide of apoC-II resulting in the familial chylomicronemia syndrome. J Lipid Res 1992. [DOI: 10.1016/s0022-2275(20)41526-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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36
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Beil FU, Fojo SS, Brewer HB, Greten H, Beisiegel U. Apolipoprotein C-II deficiency syndrome due to apo C-IIHamburg: clinical and biochemical features and HphI restriction enzyme polymorphism. Eur J Clin Invest 1992; 22:88-95. [PMID: 1349286 DOI: 10.1111/j.1365-2362.1992.tb01941.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We have characterized the clinical and biochemical features of three siblings of a kindred with severe hypertriglyceridaemia due to apolipoprotein C-II (apo C-II) deficiency caused by the mutation described as apo C-IIHamburg. The clinical syndrome is characterized by recurrent pancreatitis in two of three affected individuals, with discrete hepatosplenomegaly in all three patients and cholelithiasis in one. Eruptive xanthomas and lipemia retinalis were absent. Plasma lipoproteins were characterized by fasting chylomicronaemia, reduced low density lipoproteins (LDL) and low high density lipoproteins (HDL). The marked hypertriglyceridaemia could be corrected promptly by infusion of normal plasma. Apolipoprotein C-II (apo C-II) levels in homozygotes were very low (0.01 mg dl-1), and mean apo C-II levels in heterozygotes were lower (2.08 +/- 0.11 mg dl-1) than in normal family members (3.38 +/- 0.75 mg dl-1). Lipoprotein lipase and hepatic triglyceride lipase activities in post-heparin plasma were normal. Zonal ultracentrifugation revealed a marked increase in triglyceride-rich lipoproteins and reduced LDL and HDL. LDL consisted of two fractions with higher hydrated density of the main fraction compared with normals with a trend to normalization on a fat-free diet. The molecular defect in the apo C-II Hamburg gene has been previously identified as a donor splice site mutation in the second intron. This leads to abnormal splicing of the apo C-II Hamburg mRNA and apo C-II deficiency in plasma. The mutation causes the loss of an HphI restriction enzyme site present in the normal apo C-II gene.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- F U Beil
- Universitätsklinik Eppendorf, Hamburg, Germany
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37
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Wang CS, Hartsuck J, McConathy WJ. Structure and functional properties of lipoprotein lipase. BIOCHIMICA ET BIOPHYSICA ACTA 1992; 1123:1-17. [PMID: 1730040 DOI: 10.1016/0005-2760(92)90165-r] [Citation(s) in RCA: 81] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- C S Wang
- Protein Studies Program, Oklahoma Medical Research Foundation, Oklahoma City 73104
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38
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Hamosh A, Trapnell BC, Zeitlin PL, Montrose-Rafizadeh C, Rosenstein BJ, Crystal RG, Cutting GR. Severe deficiency of cystic fibrosis transmembrane conductance regulator messenger RNA carrying nonsense mutations R553X and W1316X in respiratory epithelial cells of patients with cystic fibrosis. J Clin Invest 1991; 88:1880-5. [PMID: 1721624 PMCID: PMC295756 DOI: 10.1172/jci115510] [Citation(s) in RCA: 102] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Cystic fibrosis (CF) is the most common, lethal inherited disorder in the Caucasian population. We have recently reported two African-American patients with nonsense mutations in each CF gene and severe pancreatic disease, but mild pulmonary disease. In order to examine the effect of these nonsense mutations on CF gene expression, bronchial and nasal epithelial cells were obtained from one of these patients (no. 246), a compound heterozygote for nonsense mutations R553X and W1316X; a healthy normal individual; a patient (no. 528) homozygous for the common CF mutation (delta F508); and a CF patient (no. 272) who carries the R553X mutation and a missense mutation, S549N. When mRNA from bronchial cells of the normal individual, the delta F508 homozygote, and the S549N/R553X compound heterozygote was reverse transcribed and amplified by polymerase chain reaction using primers derived from the CF gene, DNA fragments of the predicted size were observed. However, patient no. 246 with nonsense mutations in each CF gene has no detectable cystic fibrosis transmembrane conductance regulator (CFTR) messenger RNA, and therefore should have severely diminished, and possibly absent, CFTR protein. Furthermore, less than 2% of the CFTR transcripts in nasal epithelial cells from patient no. 272 (S549N/R553X) were derived from the gene with the nonsense mutation. We conclude that severe reduction in CFTR mRNA causes CF, but can have different consequences in the lung and pancreas.
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Affiliation(s)
- A Hamosh
- Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
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39
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Frangi D, Cicardi M, Sica A, Colotta F, Agostoni A, Davis AE. Nonsense mutations affect C1 inhibitor messenger RNA levels in patients with type I hereditary angioneurotic edema. J Clin Invest 1991; 88:755-9. [PMID: 1885769 PMCID: PMC295456 DOI: 10.1172/jci115373] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Members of two unrelated families with type I hereditary angioneurotic edema (HANE) were found to have elevated levels of C1 inhibitor (C1INH) mRNA. DNA sequence analysis of PCR-amplified monocyte C1INH mRNA revealed normal and mutant transcripts, as expected in this disorder that occurs in heterozygous individuals. Single base mutations near the 3' end of the coding sequence were identified in affected members of each family. One mutation consisted of insertion of an adenosine at position 1304 which created a premature termination codon (TAA), whereas the second consisted of deletion of the thymidine at position 1298 which created a premature termination codon (TGA) 23 nucleotides downstream. These mutations are approximately 250 nucleotides upstream of the natural termination codon. Nuclear run-off experiments in one kindred revealed no difference in transcription rates of the C1INH gene between the patients and normals. C1INH mRNA half-life experiments were not technically feasible because of the prolonged half-life of the normal transcript. Dideoxynucleotide primer extension experiments allowed the differentiation of the normal and mutant transcripts. These studies showed that the mutant transcript was not decreased relative to the normal, and this therefore was at least partially responsible for the C1INH mRNA elevation. This elevation may be due to the decreased catabolism of the mutant transcript.
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Affiliation(s)
- D Frangi
- Division of Immunology, Children's Hospital, Boston, Massachusetts
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40
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Ito Y, Azrolan N, O'Connell A, Walsh A, Breslow JL. Hypertriglyceridemia as a result of human apo CIII gene expression in transgenic mice. Science 1990; 249:790-3. [PMID: 2167514 DOI: 10.1126/science.2167514] [Citation(s) in RCA: 428] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Primary and secondary hypertriglyceridemia is common in the general population, but the biochemical basis for this disease is largely unknown. With the use of transgenic technology, two lines of mice were created that express the human apolipoprotein CIII gene. One of these mouse lines with 100 copies of the gene was found to express large amounts of the protein and to be severely hypertriglyceridemic. The other mouse line with one to two copies of the gene expressed low amounts of the protein, but nevertheless manifested mild hypertriglyceridemia. Thus, overexpression of apolipoprotein CIII can be a primary cause of hypertriglyceridemia in vivo and may provide one possible etiology for this common disorder in humans.
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Affiliation(s)
- Y Ito
- Rockefeller University, New York, NY 10021
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41
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Crecchio C, Capurso A, Pepe G. Identification of the mutation responsible for a case of plasmatic apolipoprotein CII deficiency (Apo CII-Bari). Biochem Biophys Res Commun 1990; 168:1118-27. [PMID: 1971748 DOI: 10.1016/0006-291x(90)91145-i] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
We studied a case of familial Apolipoprotein CII deficiency. By Southern hybridization, amplification and sequence analysis, the genetic defect was identified. It consists in a point mutation C- greater than G in the third exon of the gene causing a premature stop codon. Truncated at the aa. 36 of the mature form, the protein loses its functional domains, becomes inefficient and cannot be detected in the plasma, because of its high instability. The mutation destroys an RsaI site, present in the normal gene sequence. This point mutation is useful in the diagnosis of this Apolipoprotein CII deficiency.
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Affiliation(s)
- C Crecchio
- Centro SMME-CNR, Università di Bari, Italy
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42
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Fojo SS, de Gennes JL, Beisiegel U, Baggio G, Stalenhoef AF, Brunzell JD, Brewer HB. Molecular genetics of apoC-II and lipoprotein lipase deficiency. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1990; 285:329-33. [PMID: 1858563 DOI: 10.1007/978-1-4684-5904-3_40] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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43
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An Initiation Codon Mutation in the ApoC-II Gene (ApoC-II Paris) of a Patient with a Deficiency of Apolipoprotein C-II. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(19)30009-2] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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