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SUN-593 Variants in Known Monogenic Causal Genes of Hypertriglyceridemia Are Not Major Contributors for Hypertriglyceridemia in Lipodystrophy Due to a LMNA Mutation

Background: Lipodystrophy is a heterogeneous disorder of adiposity, and one common lipid manifestation is hypertriglyceridemia (HTG). The LMNA gene, which encodes for nuclear envelope proteins, is a known causal gene for heritable lipodystrophy. At present, underlying mechanisms for each clinical ma...

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Autores principales: Ueda, Masako, McIntyre, Adam D, Remaley, Alan T, Hegele, Robert A, Rader, Daniel J
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Oxford University Press 2020
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Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7207791/
http://dx.doi.org/10.1210/jendso/bvaa046.103
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author Ueda, Masako
McIntyre, Adam D
Remaley, Alan T
Hegele, Robert A
Rader, Daniel J
author_facet Ueda, Masako
McIntyre, Adam D
Remaley, Alan T
Hegele, Robert A
Rader, Daniel J
author_sort Ueda, Masako
collection PubMed
description Background: Lipodystrophy is a heterogeneous disorder of adiposity, and one common lipid manifestation is hypertriglyceridemia (HTG). The LMNA gene, which encodes for nuclear envelope proteins, is a known causal gene for heritable lipodystrophy. At present, underlying mechanisms for each clinical manifestation of lipodystrophy due to a LMNA mutation are unknown. Hypothesis: A likely explanation for HTG in lipodystrophy is the paucity of adipose tissue where excess triglycerides (TGs) are normally stored, thus it may not be due to a specific defect in lipoprotein metabolism. Consequently, rare variants in HTG-associated genes would not be expected to be major contributors for HTG in lipodystrophy with LMNA mutations. Method: A proband and her father with a clinical diagnosis of lipodystrophy were recruited into an IRB-approved study investigating molecular etiologies of dyslipidemia at the University of Pennsylvania. Next-generation sequencing (NGS) with the LipidSeq panel, targeting causal genes for lipodystrophy, and monogenic HTG was performed, and confirmed by Sanger sequencing. Also, unweighted TG-polygenic scores by summing the number of TG-raising alleles from 14 single nucleotide polymorphisms (SNPs) associated with TG levels were assessed. Results: The proband and her father were diagnosed with lipodystrophy of two different subtypes, generalized in the daughter and partial in the father. The proband reported a gradual loss of subcutaneous fat starting around age 10. A highest reported TG in the proband was19,000 mg/dL with eruptive xanthomas, whereas TG in the father was never >500 mg/dL. Their BMI’s and DEXA body fat% were 12.9 kg/m(2) and 7% in the proband, and 25.7 kg/m(2) and 25% in the father, corresponding to their fat storage capacities. The molecular analyses revealed only a lipodystrophy causal mutation in LMNA, c.29C>T, T10I with no other significant findings in18 other lipodystrophy-related genes. No deletion or duplication was identified by a targeted array CGH of LMNA. As predicted, no rare monogenic variants in HTG-causal genes (LPL, GPIHBP1, APOA5, APOC2, LMF1, GPD1) were identified in either subject. However, TG-polygenic scores were 17/28 (95(th) %ile) in the proband, and 13/28 (50(th) %ile) in the father, the same trend as the level of HTG levels seen in them. Apolipoprotein E genotypes were non-contributory, (3/3) in the proband, and (3/4) in the father. Conclusion: Our findings support that the pathophysiology of HTG in lipodystrophy is likely to be due to lack of TG-storage space (adipose tissues), and is unlikely due to a defect in lipoprotein metabolism seen in patients with rare monogenic HTG-variants. Although the HTG-polygenic score was higher in the proband, and the accumulative effects of the at-risk alleles may be contributor to the HTG phenotype, it is unlikely to be the leading cause of severe HTG seen in the proband.
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spelling pubmed-72077912020-05-13 SUN-593 Variants in Known Monogenic Causal Genes of Hypertriglyceridemia Are Not Major Contributors for Hypertriglyceridemia in Lipodystrophy Due to a LMNA Mutation Ueda, Masako McIntyre, Adam D Remaley, Alan T Hegele, Robert A Rader, Daniel J J Endocr Soc Adipose Tissue, Appetite, and Obesity Background: Lipodystrophy is a heterogeneous disorder of adiposity, and one common lipid manifestation is hypertriglyceridemia (HTG). The LMNA gene, which encodes for nuclear envelope proteins, is a known causal gene for heritable lipodystrophy. At present, underlying mechanisms for each clinical manifestation of lipodystrophy due to a LMNA mutation are unknown. Hypothesis: A likely explanation for HTG in lipodystrophy is the paucity of adipose tissue where excess triglycerides (TGs) are normally stored, thus it may not be due to a specific defect in lipoprotein metabolism. Consequently, rare variants in HTG-associated genes would not be expected to be major contributors for HTG in lipodystrophy with LMNA mutations. Method: A proband and her father with a clinical diagnosis of lipodystrophy were recruited into an IRB-approved study investigating molecular etiologies of dyslipidemia at the University of Pennsylvania. Next-generation sequencing (NGS) with the LipidSeq panel, targeting causal genes for lipodystrophy, and monogenic HTG was performed, and confirmed by Sanger sequencing. Also, unweighted TG-polygenic scores by summing the number of TG-raising alleles from 14 single nucleotide polymorphisms (SNPs) associated with TG levels were assessed. Results: The proband and her father were diagnosed with lipodystrophy of two different subtypes, generalized in the daughter and partial in the father. The proband reported a gradual loss of subcutaneous fat starting around age 10. A highest reported TG in the proband was19,000 mg/dL with eruptive xanthomas, whereas TG in the father was never >500 mg/dL. Their BMI’s and DEXA body fat% were 12.9 kg/m(2) and 7% in the proband, and 25.7 kg/m(2) and 25% in the father, corresponding to their fat storage capacities. The molecular analyses revealed only a lipodystrophy causal mutation in LMNA, c.29C>T, T10I with no other significant findings in18 other lipodystrophy-related genes. No deletion or duplication was identified by a targeted array CGH of LMNA. As predicted, no rare monogenic variants in HTG-causal genes (LPL, GPIHBP1, APOA5, APOC2, LMF1, GPD1) were identified in either subject. However, TG-polygenic scores were 17/28 (95(th) %ile) in the proband, and 13/28 (50(th) %ile) in the father, the same trend as the level of HTG levels seen in them. Apolipoprotein E genotypes were non-contributory, (3/3) in the proband, and (3/4) in the father. Conclusion: Our findings support that the pathophysiology of HTG in lipodystrophy is likely to be due to lack of TG-storage space (adipose tissues), and is unlikely due to a defect in lipoprotein metabolism seen in patients with rare monogenic HTG-variants. Although the HTG-polygenic score was higher in the proband, and the accumulative effects of the at-risk alleles may be contributor to the HTG phenotype, it is unlikely to be the leading cause of severe HTG seen in the proband. Oxford University Press 2020-05-08 /pmc/articles/PMC7207791/ http://dx.doi.org/10.1210/jendso/bvaa046.103 Text en © Endocrine Society 2020. http://creativecommons.org/licenses/by-nc-nd/4.0/ This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs licence (http://creativecommons.org/licenses/by-nc-nd/4.0/), which permits non-commercial reproduction and distribution of the work, in any medium, provided the original work is not altered or transformed in any way, and that the work is properly cited. For commercial re-use, please contact journals.permissions@oup.com
spellingShingle Adipose Tissue, Appetite, and Obesity
Ueda, Masako
McIntyre, Adam D
Remaley, Alan T
Hegele, Robert A
Rader, Daniel J
SUN-593 Variants in Known Monogenic Causal Genes of Hypertriglyceridemia Are Not Major Contributors for Hypertriglyceridemia in Lipodystrophy Due to a LMNA Mutation
title SUN-593 Variants in Known Monogenic Causal Genes of Hypertriglyceridemia Are Not Major Contributors for Hypertriglyceridemia in Lipodystrophy Due to a LMNA Mutation
title_full SUN-593 Variants in Known Monogenic Causal Genes of Hypertriglyceridemia Are Not Major Contributors for Hypertriglyceridemia in Lipodystrophy Due to a LMNA Mutation
title_fullStr SUN-593 Variants in Known Monogenic Causal Genes of Hypertriglyceridemia Are Not Major Contributors for Hypertriglyceridemia in Lipodystrophy Due to a LMNA Mutation
title_full_unstemmed SUN-593 Variants in Known Monogenic Causal Genes of Hypertriglyceridemia Are Not Major Contributors for Hypertriglyceridemia in Lipodystrophy Due to a LMNA Mutation
title_short SUN-593 Variants in Known Monogenic Causal Genes of Hypertriglyceridemia Are Not Major Contributors for Hypertriglyceridemia in Lipodystrophy Due to a LMNA Mutation
title_sort sun-593 variants in known monogenic causal genes of hypertriglyceridemia are not major contributors for hypertriglyceridemia in lipodystrophy due to a lmna mutation
topic Adipose Tissue, Appetite, and Obesity
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7207791/
http://dx.doi.org/10.1210/jendso/bvaa046.103
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