Michael A Iacocca1, Jian Wang2, Samantha Sarkar3, Jacqueline S Dron1, Thomas Lagace3, Adam D McIntyre2, Paulina Lau4, John F Robinson2, Ping Yang5, Joan H Knoll5, Henian Cao2, Ruth McPherson4, Robert A Hegele6. 1. Department of Biochemistry, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada; Robarts Research Institute, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada. 2. Robarts Research Institute, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada. 3. Department of Pathology and Laboratory Medicine, Lipoprotein Receptor Biology Laboratory, University of Ottawa Heart Institute, Ottawa, Ontario, Canada. 4. Departments of Medicine and Biochemistry, Atherogenomics Laboratory, University of Ottawa, Heart Institute, Ottawa, Ontario, Canada. 5. Department of Pathology and Laboratory Medicine, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada. 6. Department of Biochemistry, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada; Robarts Research Institute, 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. Electronic address: hegele@robarts.ca.
Abstract
BACKGROUND: Familial hypercholesterolemia (FH) is a common genetic disorder of severely elevated low-density lipoprotein (LDL) cholesterol, characterized by premature atherosclerotic cardiovascular disease. Although copy number variations (CNVs) are a large-scale mutation-type capable of explaining FH cases, they have been, to date, assessed only in the LDLR gene. Here, we performed novel CNV screening in additional FH-associated genes using a next-generation sequencing-based approach. METHODS: In 704 patients with FH, we sequenced FH-associated genes APOB, PCSK9, LDLRAP1, APOE, STAP1, LIPA, and ABCG5/8 using our LipidSeq targeted next-generation sequencing panel. Bioinformatic tools were applied to LipidSeq data for CNV screening, and identified CNVs were validated using whole-exome sequencing and microarray-based copy number analyses. RESULTS: We identified a whole-gene duplication of PCSK9 in 2 unrelated Canadian FH index cases; this PCSK9 CNV was also found to cosegregate with affected status in family members. Features in affected individuals included severely elevated LDL cholesterol levels that were refractory to intensive statin therapy, pronounced clinical stigmata, premature cardiovascular events, and a plasma PCSK9 of approximately 5000 ng/mL in 1 index case. We found no CNVs in APOB, LDLRAP1, APOE, STAP1, LIPA, and ABCG5/8 in our cohort of 704 FH individuals. CONCLUSIONS: Here, we report the first description of a CNV affecting the PCSK9 gene in FH. This finding is associated with a profound FH phenotype and the highest known plasma PCSK9 level reported in a human. This finding also has therapeutic relevance, as elevated PCSK9 levels may limit the efficacy of high-dose statin therapy and also PCSK9 inhibition.
BACKGROUND:Familial hypercholesterolemia (FH) is a common genetic disorder of severely elevated low-density lipoprotein (LDL) cholesterol, characterized by premature atherosclerotic cardiovascular disease. Although copy number variations (CNVs) are a large-scale mutation-type capable of explaining FH cases, they have been, to date, assessed only in the LDLR gene. Here, we performed novel CNV screening in additional FH-associated genes using a next-generation sequencing-based approach. METHODS: In 704 patients with FH, we sequenced FH-associated genes APOB, PCSK9, LDLRAP1, APOE, STAP1, LIPA, and ABCG5/8 using our LipidSeq targeted next-generation sequencing panel. Bioinformatic tools were applied to LipidSeq data for CNV screening, and identified CNVs were validated using whole-exome sequencing and microarray-based copy number analyses. RESULTS: We identified a whole-gene duplication of PCSK9 in 2 unrelated Canadian FH index cases; this PCSK9 CNV was also found to cosegregate with affected status in family members. Features in affected individuals included severely elevated LDL cholesterol levels that were refractory to intensive statin therapy, pronounced clinical stigmata, premature cardiovascular events, and a plasma PCSK9 of approximately 5000 ng/mL in 1 index case. We found no CNVs in APOB, LDLRAP1, APOE, STAP1, LIPA, and ABCG5/8 in our cohort of 704 FH individuals. CONCLUSIONS: Here, we report the first description of a CNV affecting the PCSK9 gene in FH. This finding is associated with a profound FH phenotype and the highest known plasma PCSK9 level reported in a human. This finding also has therapeutic relevance, as elevated PCSK9 levels may limit the efficacy of high-dose statin therapy and also PCSK9 inhibition.
Authors: Jacqueline S Dron; Jian Wang; Adam D McIntyre; Henian Cao; John F Robinson; P Barton Duell; Priya Manjoo; James Feng; Irina Movsesyan; Mary J Malloy; Clive R Pullinger; John P Kane; Robert A Hegele Journal: J Lipid Res Date: 2019-09-13 Impact factor: 5.922
Authors: Amanda J Berberich; Céline Huot; Henian Cao; Adam D McIntyre; John F Robinson; Jian Wang; Robert A Hegele Journal: J Clin Endocrinol Metab Date: 2019-08-01 Impact factor: 5.958
Authors: Markus Gulilat; Tyler Lamb; Wendy A Teft; Jian Wang; Jacqueline S Dron; John F Robinson; Rommel G Tirona; Robert A Hegele; Richard B Kim; Ute I Schwarz Journal: BMC Med Genomics Date: 2019-06-03 Impact factor: 3.063
Authors: Babunageswararao Kanuri; Vincent Fong; April Haller; David Y Hui; Shailendra B Patel Journal: BMC Med Genet Date: 2020-11-23 Impact factor: 2.103
Authors: Jacqueline S Dron; Jian Wang; Adam D McIntyre; Michael A Iacocca; John F Robinson; Matthew R Ban; Henian Cao; Robert A Hegele Journal: BMC Med Genomics Date: 2020-02-10 Impact factor: 3.063