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Variants of Unknown Significance in Genes Associated with Heritable Thoracic Aortic Disease Can Be Low Penetrant "Risk Variants".

ABSTRACT: Thoracic aortic aneurysms leading to acute aortic dissections are a preventable cause of premature deaths if individuals at risk can be identified. Individuals with early-onset aortic dissections without a family history or syndromic features have an increased burden of rare genetic variants of unknown significance (VUSs) in genes with pathogenic variants for heritable thoracic aortic disease (HTAD). We assessed the role of VUSs in the development of disease using both in vitro enzymatic assays and mouse models. VUSs in LOX and MYLK identified in individuals with acute aortic dissections were assayed to determine whether they disrupted enzymatic activity. A subset of VUSs reduced enzymatic activity compared to the wild-type proteins but less than pathogenic variants. Additionally, a Myh11 variant, p.Arg247Cys, which does not cause aortic disease in either humans or mice, was crossed with the Acta2-/- mouse, which has aortic enlargement with age while Acta2+/- mice do not. Acta2+/-Myh11R247C/R247C mice have aortic dilation by 3 months of age without medial degeneration, indicating that two variants not known to cause disease do lead to aortic enlargement in combination. Furthermore, the addition of Myh11R247C/R247C to the Acta2-/- mouse model accelerates aortic enlargement and increases medial degeneration. Therefore, our results emphasize the need for a classification system for variants in Mendelian genes that goes beyond the 5-tier system of pathogenic, likely pathogenic, VUS, likely benign, and benign, and includes a designation for low-penetrant "risk variants" that trigger disease either in combination with other risk factors or in a stochastic manner.

SUBMITTER: Kwartler CS

PROVIDER: S-EPMC6035370 | biostudies-literature | 2018 Jul

REPOSITORIES: biostudies-literature

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Variants of Unknown Significance in Genes Associated with Heritable Thoracic Aortic Disease Can Be Low Penetrant "Risk Variants".

Kwartler Callie S CS Gong Limin L Chen Jiyuan J Wang Shanzhi S Kulmacz Richard R Duan Xue-Yan XY Janda Alexandra A Huang Jian J Kamm Kristine E KE Stull James T JT Guo Dongchuan D Milewicz Dianna M DM

American journal of human genetics 20180628 1

Thoracic aortic aneurysms leading to acute aortic dissections are a preventable cause of premature deaths if individuals at risk can be identified. Individuals with early-onset aortic dissections without a family history or syndromic features have an increased burden of rare genetic variants of unknown significance (VUSs) in genes with pathogenic variants for heritable thoracic aortic disease (HTAD). We assessed the role of VUSs in the development of disease using both in vitro enzymatic assays ...[more]

PMID: 29961567

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Project description:BackgroundThoracic aortic aneurysms progressively enlarge and predispose to acute aortic dissections. Up to 25% of individuals with thoracic aortic disease harbor an underlying Mendelian pathogenic variant. An evidence-based strategy for selection of genes to test in hereditary thoracic aortic aneurysm and dissection (HTAAD) helps inform family screening and intervention to prevent life-threatening thoracic aortic events.ObjectivesThe purpose of this study was to accurately identify genes that predispose to HTAAD using the Clinical Genome Resource (ClinGen) framework.MethodsWe applied the semiquantitative ClinGen framework to assess presumed gene-disease relationships between 53 candidate genes and HTAAD. Genes were classified as causative for HTAAD if they were associated with isolated thoracic aortic disease and were clinically actionable, triggering routine aortic surveillance, intervention, and family cascade screening. All gene-disease assertions were evaluated by a pre-defined curator-expert pair and subsequently discussed with an expert panel.ResultsGenes were classified based on the strength of association with HTAAD into 5 categories: definitive (n = 9), strong (n = 2), moderate (n = 4), limited (n = 15), and no reported evidence (n = 23). They were further categorized by severity of associated aortic disease and risk of progression. Eleven genes in the definitive and strong groups were designated as "HTAAD genes" (category A). Eight genes were classified as unlikely to be progressive (category B) and 4 as low risk (category C). The remaining genes were recent genes with an uncertain classification or genes with no evidence of association with HTAAD.ConclusionsThe ClinGen framework is useful to semiquantitatively assess the strength of gene-disease relationships for HTAAD. Gene categories resulting from the curation may inform clinical laboratories in the development, interpretation, and subsequent clinical implications of genetic testing for patients with aortic disease.

Project description:Heritable aortic aneurysm is an increasingly recognized cause of morbidity and mortality. Whilst Marfan syndrome (MFS) is well-known, the clinical presentation and prognosis of more newly described genetic syndromes is less familiar to clinicians. There is a particular lack of knowledge regarding clinical outcomes for non-syndromal heritable aortic disease. This study investigated the presentation, clinical course and survival of patients with syndromal [Loeys-Dietz, aneurysm-osteoarthritis, and aneurysm-cerebral arteriopathy (ACTA2) syndrome] and non-syndromal heritable aortic disease in comparison to MFS. The study group includes 536 individuals (283 Marfan, 176 non-syndromal heritable aortopathy, 36 aneurysm-osteoarthritis, 32 Loeys-Dietz, and 9 ACTA2 aneurysm) enrolled in a longitudinal clinical follow-up between 1990 and 2022. Age at diagnosis differed between groups: Marfan = 22.0 ± 16.6; Loeys-Dietz = 29.6 ± 21.5; aneurysm-osteoarthritis = 36.4 ± 18.8; ACTA2 aneurysm = 43.4 ± 18.6; non-syndromal heritable aortopathy = 47.2 ± 16.6 years (p < 0.001). Aortic dissection was the presenting event in 8% individuals with Marfan compared to 27% with non-syndromal heritable aortopathy and 34% with Loeys-Dietz syndrome (p < 0.01). Mean follow-up duration for the group was 16.4 years (range 0.2-30 years) and 74 individuals died during follow-up (Marfan = 52, Loeys-Dietz = 6, aneurysm-osteoarthritis = 4, ACTA2 aneurysm = 1, heritable non-syndromal aortopathy = 11). At 10 years follow-up, actuarial mean survivals were: aneurysm-osteoarthritis = 77.5 ± 10.4%; Loeys-Dietz = 90.0 ± 6.8%; Marfan = 94.6 ± 1.4%; heritable non-syndromal aortopathy = 95.9 ± 2.1% (NS). There were 60 aortic dissections (24 Type A, 36 Type B) during follow-up. At 10 years, survival free of dissection was comparable between groups: aneurysm-osteoarthritis = 90.7 ± 6.4%; Loeys-Dietz = 94.4 ± 5.4%; Marfan = 96.1 ± 1.2%; heritable non-syndromal aortopathy = 93.9 ± 2.3%, with similar findings at 20 years. Prophylactic aortic surgery was a first event during follow-up for 196 individuals (ACTA2 aneurysm = 3; aneurysm-osteoarthritis = 10; Loeys-Dietz = 19; Marfan = 119; heritable non-syndromal aortopathy = 45). A second surgical intervention was required in 45 individuals and a third intervention in 21 individuals. At 10 years follow-up, survival free of surgery differed between groups: aneurysm-osteoarthritis = 68.5 ± 10.1%; Loeys-Dietz = 40.8 ± 11.2%; Marfan = 75.5 ± 2.7%; heritable non-syndromal aortopathy = 63.8 ± 4.7% (p < 0.001). At 20 years follow-up mean survival free of surgery was: aneurysm-osteoarthritis = 26.6 ± 14.7%; Loeys-Dietz = 9.1 ± 8.2%; Marfan = 57.2 ± 3.4%; heritable non-syndromal aortopathy = 41.6 ± 8.2% (p < 0.001). Diagnosis of newer syndromic and non-syndromal heritable aortopathies is delayed compared to MFS, with associated complications of presentation with aortic dissection. Survival of individuals enrolled in follow-up surveillance is comparable between different genetic aortopathies, however aortic dissections still occur and need for surgical intervention is high.

Dataset Information

Variants of Unknown Significance in Genes Associated with Heritable Thoracic Aortic Disease Can Be Low Penetrant "Risk Variants".

Publications

Variants of Unknown Significance in Genes Associated with Heritable Thoracic Aortic Disease Can Be Low Penetrant "Risk Variants".

Similar Datasets

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