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Perera SD, Wang J, McIntyre AD, Hegele RA. Variability of longitudinal triglyceride phenotype in patients heterozygous for pathogenic APOA5 variants. J Clin Lipidol 2023; 17:659-665. [PMID: 37586912 DOI: 10.1016/j.jacl.2023.08.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2023] [Revised: 07/15/2023] [Accepted: 08/03/2023] [Indexed: 08/18/2023]
Abstract
BACKGROUND Biallelic pathogenic variants in APOA5 are an infrequent cause of familial chylomicronemia syndrome characterized by severe, refractory hypertriglyceridemia (HTG), and fasting plasma triglyceride (TG) >10 mmol/L (>875 mg/dL). The TG phenotype of heterozygous individuals with one copy of a pathogenic APOA5 variant is less familiar. We evaluated the longitudinal TG phenotype of individuals with a single pathogenic APOA5 variant allele. METHODS Medically stable outpatients from Ontario, Canada were selected for study based on having: 1) a rare pathogenic APOA5 variant in a single allele; and 2) at least three serial fasting TG measurements obtained over >1.5 years of follow-up. RESULTS Seven patients were followed for a mean of 5.3 ± 3.7 years. Fasting TG levels varied widely both within and between patients. Three patients displayed at least one normal TG measurement (<2.0 mmol/L or <175 mg/dL). All patients displayed mild-to-moderate HTG (2 to 9.9 mmol/L or 175 to 875 mg/dL) at multiple time points. Five patients displayed at least one severe HTG measurement. 10%, 54%, and 36% of all TG measurements were in normal, mild-to-moderate, and severe HTG ranges, respectively. CONCLUSIONS Heterozygosity for pathogenic variants in APOA5 is associated with highly variable TG phenotypes both within and between patients. Heterozygosity confers susceptibility to elevated TG levels, with secondary factors likely modulating the phenotypic severity.
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Affiliation(s)
- Shehan D Perera
- Robarts Research Institute, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada; Department of Biochemistry, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada
| | - Jian Wang
- Robarts Research Institute, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada
| | - Adam D McIntyre
- Robarts Research Institute, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada
| | - Robert A Hegele
- Robarts Research Institute, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada; Department of Biochemistry, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada; Department of Medicine, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada.
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Liu S, Wang Z, Zheng X, Zhang Y, Wei S, OuYang H, Liang J, Chen N, Zeng W, Jiang J. Case Report: Successful Management of a 29-Day-Old Infant With Severe Hyperlipidemia From a Novel Homozygous Variant of GPIHBP1 Gene. Front Pediatr 2022; 10:792574. [PMID: 35359903 PMCID: PMC8960264 DOI: 10.3389/fped.2022.792574] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2021] [Accepted: 02/03/2022] [Indexed: 01/27/2023] Open
Abstract
BACKGROUND Severe hyperlipidemia is characterized by markedly elevated blood triglyceride levels and severe early-onset cardiovascular diseases, pancreatitis, pancreatic necrosis or persistent multiple organ failure if left untreated. It is a rare autosomal recessive metabolic disorder originated from the variants of lipoprotein lipase gene, and previous studies have demonstrated that most cases with severe hyperlipidemia are closely related to the variants of some key genes for lipolysis, such as LPL, APOC2, APOA5, LMF1, and GPIHBP1. Meanwhile, other unidentified causes also exist and are equally worthy of attention. METHODS The 29-day-old infant was diagnosed with severe hyperlipidemia, registering a plasma triglyceride level as high as 25.46 mmol/L. Whole exome sequencing was conducted to explore the possible pathogenic gene variants for this patient. RESULTS The infant was put on a low-fat diet combined with pharmacological therapy, which was successful in restraining the level of serum triglyceride and total cholesterol to a low to medium range during the follow-ups. The patient was found to be a rare novel homozygous duplication variant-c.45_48dupGCGG (Pro17Alafs*22) in GPIHBP1 gene-leading to a frameshift which failed to form the canonical termination codon TGA. The mutant messenger RNA should presumably produce a peptide consisting of 16 amino acids at the N-terminus, with 21 novel amino acids on the heels of the wild-type protein. CONCLUSIONS Our study expands on the spectrum of GPIHBP1 variants and contributes to a more comprehensive understanding of the genetic diagnosis, genetic counseling, and multimodality therapy of families with severe hyperlipidemia. Our experience gained in this study is also contributory to a deeper insight into severe hyperlipidemia and highlights the importance of molecular genetic tests.
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Affiliation(s)
- Shu Liu
- Children Inherited Metabolism and Endocrine Department, Guangdong Women and Children Hospital, Guangzhou, China
| | - Zhiqing Wang
- Guangdong Provincial Key Laboratory of Gastroenterology, Department of Gastroenterology, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Xianhua Zheng
- Department of Clinical Laboratory, Guangdong Women and Children Hospital, Guangzhou, China
| | - Ye Zhang
- Children Inherited Metabolism and Endocrine Department, Guangdong Women and Children Hospital, Guangzhou, China
| | - Sisi Wei
- Children Inherited Metabolism and Endocrine Department, Guangdong Women and Children Hospital, Guangzhou, China
| | - Haimei OuYang
- Children Inherited Metabolism and Endocrine Department, Guangdong Women and Children Hospital, Guangzhou, China
| | - Jinqun Liang
- Children Inherited Metabolism and Endocrine Department, Guangdong Women and Children Hospital, Guangzhou, China
| | - Nuan Chen
- Children Inherited Metabolism and Endocrine Department, Guangdong Women and Children Hospital, Guangzhou, China
| | - Weihong Zeng
- Children Inherited Metabolism and Endocrine Department, Guangdong Women and Children Hospital, Guangzhou, China
| | - Jianhui Jiang
- Children Inherited Metabolism and Endocrine Department, Guangdong Women and Children Hospital, Guangzhou, China
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Dron JS, Wang J, McIntyre AD, Iacocca MA, Robinson JF, Ban MR, Cao H, Hegele RA. Six years' experience with LipidSeq: clinical and research learnings from a hybrid, targeted sequencing panel for dyslipidemias. BMC Med Genomics 2020; 13:23. [PMID: 32041611 PMCID: PMC7011550 DOI: 10.1186/s12920-020-0669-2] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Accepted: 01/23/2020] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND In 2013, our laboratory designed a targeted sequencing panel, "LipidSeq", to study the genetic determinants of dyslipidemia and metabolic disorders. Over the last 6 years, we have analyzed 3262 patient samples obtained from our own Lipid Genetics Clinic and international colleagues. Here, we highlight our findings and discuss research benefits and clinical implications of our panel. METHODS LipidSeq targets 69 genes and 185 single-nucleotide polymorphisms (SNPs) either causally related or associated with dyslipidemia and metabolic disorders. This design allows us to simultaneously evaluate monogenic-caused by rare single-nucleotide variants (SNVs) or copy-number variants (CNVs)-and polygenic forms of dyslipidemia. Polygenic determinants were assessed using three polygenic scores, one each for low-density lipoprotein cholesterol, triglyceride, and high-density lipoprotein cholesterol. RESULTS Among 3262 patient samples evaluated, the majority had hypertriglyceridemia (40.1%) and familial hypercholesterolemia (28.3%). Across all samples, we identified 24,931 unique SNVs, including 2205 rare variants predicted disruptive to protein function, and 77 unique CNVs. Considering our own 1466 clinic patients, LipidSeq results have helped in diagnosis and improving treatment options. CONCLUSIONS Our LipidSeq design based on ontology of lipid disorders has enabled robust detection of variants underlying monogenic and polygenic dyslipidemias. In more than 50 publications related to LipidSeq, we have described novel variants, the polygenic nature of many dyslipidemias-some previously thought to be primarily monogenic-and have uncovered novel mechanisms of disease. We further demonstrate several tangible clinical benefits of its use.
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Affiliation(s)
- Jacqueline S. Dron
- Robarts Research Institute, Schulich School of Medicine and Dentistry, Western University, 1151 Richmond St, London, ON N6A 5B7 Canada
- Department of Biochemistry, Schulich School of Medicine and Dentistry, Western University, 1151 Richmond Street, London, ON N6A 5B7 Canada
| | - Jian Wang
- Robarts Research Institute, Schulich School of Medicine and Dentistry, Western University, 1151 Richmond St, London, ON N6A 5B7 Canada
| | - Adam D. McIntyre
- Robarts Research Institute, Schulich School of Medicine and Dentistry, Western University, 1151 Richmond St, London, ON N6A 5B7 Canada
| | - Michael A. Iacocca
- Robarts Research Institute, Schulich School of Medicine and Dentistry, Western University, 1151 Richmond St, London, ON N6A 5B7 Canada
- Department of Biochemistry, Schulich School of Medicine and Dentistry, Western University, 1151 Richmond Street, London, ON N6A 5B7 Canada
- Department of Biomedical Data Science, Stanford School of Medicine, Stanford University, 450 Serra Mall, Stanford, CA 94305 USA
| | - John F. Robinson
- Robarts Research Institute, Schulich School of Medicine and Dentistry, Western University, 1151 Richmond St, London, ON N6A 5B7 Canada
| | - Matthew R. Ban
- Robarts Research Institute, Schulich School of Medicine and Dentistry, Western University, 1151 Richmond St, London, ON N6A 5B7 Canada
| | - Henian Cao
- Robarts Research Institute, Schulich School of Medicine and Dentistry, Western University, 1151 Richmond St, London, ON N6A 5B7 Canada
| | - Robert A. Hegele
- Robarts Research Institute, Schulich School of Medicine and Dentistry, Western University, 1151 Richmond St, London, ON N6A 5B7 Canada
- Department of Biochemistry, Schulich School of Medicine and Dentistry, Western University, 1151 Richmond Street, London, ON N6A 5B7 Canada
- Department of Medicine, Schulich School of Medicine and Dentistry, Western University, 1151 Richmond St, London, ON N6A 5B7 Canada
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