scholarly journals Arrhythmia variant associations and reclassifications in the eMERGE-III sequencing study

2021 ◽  
Author(s):  
Andrew M Glazer ◽  
Giovanni Davogustto ◽  
Christian M Shaffer ◽  
Carlos G Vanoye ◽  
Reshma R Desai ◽  
...  
Keyword(s):  
Rare Variants ◽  
Disease Risk ◽  
Disease Genes ◽  
Functional Evaluation ◽  
Functional Studies ◽  
Large Numbers ◽  
Inherited Arrhythmia ◽  
Genomic Screening ◽  
Uncertain Significance

In 21,846 eMERGE-III participants, sequencing 10 arrhythmia syndrome disease genes identified 123 individuals with pathogenic or likely pathogenic (P/LP) variants. Compared to non-carriers, P/LP carriers had a significantly higher burden of arrhythmia phenotypes in their electronic health records (EHRs). Fifty one participants had variant results returned. Eighteen of these 51 participants had inherited arrhythmia syndrome diagnoses (primarily long QT syndrome), and 11/18 of these diagnoses were made only after variant results were returned. After in vitro functional evaluation of 50 variants of uncertain significance (VUS), we reclassified 11 variants: 3 to likely benign and 8 to P/LP. As large numbers of people are sequenced, the disease risk from rare variants in arrhythmia genes can be assessed by integrating genomic screening, EHR phenotypes, and in vitro functional studies.

scholarly journals Arrhythmia Variant Associations and Reclassifications in the eMERGE-III Sequencing Study

Circulation ◽  
2021 ◽  
Author(s):  
Andrew M Glazer ◽  
Giovanni E. Davogustto ◽  
Christian M. Shaffer ◽  
Carlos G Vanoye ◽  
Reshma R. Desai ◽  
...  
Keyword(s):  
Genetic Testing ◽  
Disease Risk ◽  
Large Population ◽  
Hek293 Cells ◽  
Disease Genes ◽  
Mendelian Disease ◽  
Functional Evaluation ◽  
Variants Of Uncertain Significance ◽  
Uncertain Significance

Background: Sequencing Mendelian arrhythmia genes in individuals without an indication for arrhythmia genetic testing can identify carriers of pathogenic or likely pathogenic (P/LP) variants. However, the extent to which these variants are associated with clinically meaningful phenotypes before or after return of variant results (RoR) is unclear. In addition, the majority of discovered variants are currently classified as Variants of Uncertain Significance (VUS), limiting clinical actionability. Methods: The eMERGE-III study is a multi-center prospective cohort which included 21,846 participants without prior indication for cardiac genetic testing. Participants were sequenced for 109 Mendelian disease genes, including 10 linked to arrhythmia syndromes. Variant carriers were assessed with Electronic Health Record (EHR)-derived phenotypes and follow-up clinical examination. Selected VUS (n=50) were characterized in vitro with automated electrophysiology experiments in HEK293 cells. Results: As previously reported, 3.0% of participants had pathogenic or likely pathogenic (P/LP) variants in the 109 genes. Herein, we report 120 participants (0.6%) with P/LP arrhythmia variants. Compared to non-carriers, arrhythmia P/LP carriers had a significantly higher burden of arrhythmia phenotypes in their EHRs. Fifty four participants had variant results returned. Nineteen of these 54 participants had inherited arrhythmia syndrome diagnoses (primarily long QT syndrome), and 12/19 of these diagnoses were made only after variant results were returned (0.05%). After in vitro functional evaluation of 50 variants of uncertain significance (VUS), we reclassified 11 variants: 3 to likely benign and 8 to P/LP. Conclusions: Genome sequencing in a large population without indication for arrhythmia genetic testing identified phenotype-positive carriers of variants in congenital arrhythmia syndrome disease genes. As large numbers of people are sequenced, the disease risk from rare variants in arrhythmia genes can be assessed by integrating genomic screening, EHR phenotypes, and in vitro functional studies.

scholarly journals A Bayesian method using sparse data to estimate penetrance of disease-associated genetic variants

2019 ◽  
Author(s):  
Brett M. Kroncke ◽  
Derek K. Smith ◽  
Andrew M. Glazer ◽  
Dan M. Roden ◽  
Jeffrey D. Blume
Keyword(s):  
Rare Variants ◽  
Disease Risk ◽  
Genomic Medicine ◽  
Disease Genes ◽  
Mendelian Disease ◽  
Phenotypic Data ◽  
Prior Probabilities ◽  
Cardiac Gene ◽  
Risk Of Disease

AbstractPurposeA major challenge in genomic medicine is how to best predict risk of disease from rare variants discovered in Mendelian disease genes but with limited phenotypic data. We have recently used Bayesian methods to show that in vitro functional measurements and computational pathogenicity classification of variants in the cardiac gene SCN5A correlate with rare arrhythmia penetrance. We hypothesized that similar predictors could be used to impute variant-specific penetrance prior probabilities.MethodsFrom a review of 756 publications, we developed a pattern mixture algorithm, based on a Bayesian Beta-Binomial model, to generate SCN5A variant-specific penetrance priors for the heart arrhythmia Brugada syndrome (BrS).ResultsThe resulting priors correlate with mean BrS penetrance posteriors (cross validated R2= 0.41). SCN5A variant function and structural context provide the most information predictive of BrS penetrance. The resulting priors are interpretable as equivalent to the observation of affected and unaffected carriers.ConclusionsBayesian estimates of penetrance can efficiently integrate variant-specific data (e.g. functional, structural, and sequence) to accurately estimate disease risk attributable to individual variants. We suggest this formulation of penetrance is quantitative, probabilistic, and more precise than, but consistent with, discrete pathogenicity classification approaches.

scholarly journals Genetic Studies of Hypertrophic Cardiomyopathy in Singaporeans Identify Variants in TNNI3 and TNNT2 That Are Common in Chinese Patients

2020 ◽  
Vol 13 (5) ◽  
pp. 424-434
Author(s):  
Chee Jian Pua ◽  
Nevin Tham ◽  
Calvin W.L. Chin ◽  
Roddy Walsh ◽  
Chiea Chuen Khor ◽  
...  
Keyword(s):  
Hypertrophic Cardiomyopathy ◽  
East Asian ◽  
Left Ventricular ◽  
Chinese Patients ◽  
Disease Genes ◽  
Variant Of Uncertain Significance ◽  
Variants Of Uncertain Significance ◽  
Functional Studies ◽  
Uncertain Significance

Background: To assess the genetic architecture of hypertrophic cardiomyopathy (HCM) in patients of predominantly Chinese ancestry. Methods: We sequenced HCM disease genes in Singaporean patients (n=224) and Singaporean controls (n=3634), compared findings with additional populations and White HCM cohorts (n=6179), and performed in vitro functional studies. Results: Singaporean HCM patients had significantly fewer confidently interpreted HCM disease variants (pathogenic/likely pathogenic: 18%, P <0.0001) but an excess of variants of uncertain significance (24%, P <0.0001), as compared to Whites (pathogenic/likely pathogenic: 31%, excess of variants of uncertain significance: 7%). Two missense variants in thin filament encoding genes were commonly seen in Singaporean HCM (TNNI3:p.R79C, disease allele frequency [AF]=0.018; TNNT2:p.R286H, disease AF=0.022) and are enriched in Singaporean HCM when compared with Asian controls (TNNI3:p.R79C, Singaporean controls AF=0.0055, P =0.0057, genome aggregation database-East Asian AF=0.0062, P =0.0086; TNNT2:p.R286H, Singaporean controls AF=0.0017, P <0.0001, genome aggregation database-East Asian AF=0.0009, P <0.0001). Both these variants have conflicting annotations in ClinVar and are of low penetrance (TNNI3:p.R79C, 0.7%; TNNT2:p.R286H, 2.7%) but are predicted to be deleterious by computational tools. In population controls, TNNI3:p.R79C carriers had significantly thicker left ventricular walls compared with noncarriers while its etiological fraction is limited (0.70 [95% CI, 0.35–0.86]) and thus TNNI3:p.R79C is considered variant of uncertain significance. Mutant TNNT2:p.R286H iPSC-CMs (induced pluripotent stem cells derived cardiomyocytes) show hypercontractility, increased metabolic requirements, and cellular hypertrophy and the etiological fraction (0.93 [95% CI, 0.83–0.97]) support the likely pathogenicity of TNNT2:p.R286H. Conclusions: As compared with Whites, Chinese HCM patients commonly have low penetrance risk alleles in TNNT2 or TNNI3 but exhibit few clinically actionable HCM variants overall. This highlights the need for greater study of HCM genetics in non-White populations.

scholarly journals Functional Analyses of HNF1A-MODY Variants Refine the Interpretation of Identified Sequence Variants

2020 ◽  
Vol 105 (4) ◽  
pp. e1377-e1386
Author(s):  
Jana Malikova ◽  
Alba Kaci ◽  
Petra Dusatkova ◽  
Ingvild Aukrust ◽  
Janniche Torsvik ◽  
...  
Keyword(s):  
Dna Binding ◽  
Rare Variants ◽  
Functional Evaluation ◽  
Functional Protein ◽  
Functional Studies ◽  
Uncertain Significance ◽  
Hnf1a Gene ◽  
Nuclear Factor 1 ◽  
Functional Analyses

Abstract Context While rare variants of the hepatocyte nuclear factor-1 alpha (HNF1A) gene can cause maturity-onset diabetes of the young (HNF1A-MODY), other variants can be risk factors for the development of type 2 diabetes. As has been suggested by the American College of Medical Genetics (ACMG) guidelines for variant interpretation, functional studies provide strong evidence to classify a variant as pathogenic. Objective We hypothesized that a functional evaluation can improve the interpretation of the HNF1A variants in our Czech MODY Registry. Design, Settings, and Participants We studied 17 HNF1A variants that were identified in 48 individuals (33 female/15 male) from 20 Czech families with diabetes, using bioinformatics in silico tools and functional protein analyses (transactivation, protein expression, DNA binding, and nuclear localization). Results Of the 17 variants, 12 variants (p.Lys120Glu, p.Gln130Glu, p.Arg131Pro, p.Leu139Pro, p.Met154Ile, p.Gln170Ter, p.Glu187SerfsTer40, p.Phe215SerfsTer18, p.Gly253Arg, p.Leu383ArgfsTer3, p.Gly437Val, and p.Thr563HisfsTer85) exhibited significantly reduced transcriptional activity or DNA binding (&lt; 40%) and were classified as (likely) pathogenic, 2/17 variants were (likely) benign and 3/17 remained of uncertain significance. Functional analyses allowed for the reclassification of 10/17 variants (59%). Diabetes treatment was improved in 20/29 (69%) carriers of (likely) pathogenic HNF1A variants. Conclusion Functional evaluation of the HNF1A variants is necessary to better predict the pathogenic effects and to improve the diagnostic interpretation and treatment, particularly in cases where the cosegregation or family history data are not available or where the phenotype is more diverse and overlaps with other types of diabetes.

scholarly journals Novel MSX1 variants identified in families with nonsyndromic oligodontia

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Jinglei Zheng ◽  
Miao Yu ◽  
Haochen Liu ◽  
Tao Cai ◽  
Hailan Feng ◽  
...  
Keyword(s):  
Current Data ◽  
Phenotypic Characterization ◽  
Functional Evaluation ◽  
Gene Variants ◽  
Chinese Families ◽  
Whole Exome ◽  
Bioinformatics Databases ◽  
Uncertain Significance ◽  
Vitro Analysis

AbstractThe goal of this study was to identify MSX1 gene variants in multiple Chinese families with nonsyndromic oligodontia and analyse the functional influence of these variants. Whole-exome sequencing (WES) and Sanger sequencing were performed to identify the causal gene variants in five families with nonsyndromic oligodontia, and a series of bioinformatics databases were used for variant confirmation and functional prediction. Phenotypic characterization of the members of these families was described, and an in vitro analysis was performed for functional evaluation. Five novel MSX1 heterozygous variants were identified: three missense variants [c.662A>C (p.Q221P), c.670C>T (p.R224C), and c.809C>T (p.S270L)], one nonsense variant [c.364G>T (p.G122*)], and one frameshift variant [c.277delG (p.A93Rfs*67)]. Preliminary in vitro studies demonstrated that the subcellular localization of MSX1 was abnormal with the p.Q221P, p.R224C, p.G122*, and p.A93Rfs*67 variants compared to the wild type. Three variants (p.Q221P, p.G122*, and p.A93Rfs*67) were classified as pathogenic or likely pathogenic, while p.S270L and p.R224C were of uncertain significance in the current data. Moreover, we summarized and analysed the MSX1-related tooth agenesis positions and found that the type and variant locus were not related to the severity of tooth loss. Our results expand the variant spectrum of nonsyndromic oligodontia and provide valuable information for genetic counselling.

scholarly journals Janus-faced EPHB4-associated disorders: novel pathogenic variants and unreported intrafamilial overlapping phenotypes

2021 ◽  
Author(s):  
Silvia Martin-Almedina ◽  
Kazim Ogmen ◽  
Ege Sackey ◽  
Dionysios Grigoriadis ◽  
Christina Karapouliou ◽  
...  
Keyword(s):  
Subcellular Localization ◽  
Fetal Hydrops ◽  
Clinical Phenotypes ◽  
Functional Studies ◽  
Pathogenic Variants ◽  
Disease Mechanisms ◽  
Novel Variants ◽  
Uncertain Significance ◽  
Clinical Phenotyping

Abstract Purpose Several clinical phenotypes including fetal hydrops, central conducting lymphatic anomaly or capillary malformations with arteriovenous malformations 2 (CM-AVM2) have been associated with EPHB4 (Ephrin type B receptor 4) variants, demanding new approaches for deciphering pathogenesis of novel variants of uncertain significance (VUS) identified in EPHB4, and for the identification of differentiated disease mechanisms at the molecular level. Methods Ten index cases with various phenotypes, either fetal hydrops, CM-AVM2, or peripheral lower limb lymphedema, whose distinct clinical phenotypes are described in detail in this study, presented with a variant in EPHB4. In vitro functional studies were performed to confirm pathogenicity. Results Pathogenicity was demonstrated for six of the seven novel EPHB4 VUS investigated. A heterogeneity of molecular disease mechanisms was identified, from loss of protein production or aberrant subcellular localization to total reduction of the phosphorylation capability of the receptor. There was some phenotype–genotype correlation; however, previously unreported intrafamilial overlapping phenotypes such as lymphatic-related fetal hydrops (LRFH) and CM-AVM2 in the same family were observed. Conclusion This study highlights the usefulness of protein expression and subcellular localization studies to predict EPHB4 variant pathogenesis. Our accurate clinical phenotyping expands our interpretation of the Janus-faced spectrum of EPHB4-related disorders, introducing the discovery of cases with overlapping phenotypes.

scholarly journals Familial heterogeneity in breast cancer predisposition: a study of 22 Utah families

2016 ◽  
Author(s):  
Elizabeth O’Brien ◽  
Richard A. Kerber ◽  
Raymond L. White
Keyword(s):  
Breast Cancer ◽  
Rare Variants ◽  
Disease Risk ◽  
Breast Cancer Predisposition ◽  
Large Numbers ◽  
Genome Wide ◽  
A Genome ◽  
Medium Risk ◽  
Genomic Regions ◽  
Marker Spacing

AbstractThe problem of “missing heritability” in genome-wide analyses of complex diseases is thought to be attributable to some combination of: rare variants of moderate to large effect, common variants of very small effect, and epigenetic, epistatic, or shared environmental effects. Rare variants do not affect large numbers of people by definition, but identified genes and pathways frequently lead to important insights into pathogenesis, and become targets of chemoprevention or therapy. Family studies remain an efficient way to identify rare variants with sizable effects on disease risk. We present a genome-wide study of breast cancer in 22 large high-risk families including 154 women diagnosed with breast cancer. Appropriate marker spacing was achieved by simulation studies of founder haplotypes to reduce the chance that linkage disequilibrium produced spurious linkage peaks. For each family, we generated 100 simulations of null linkage genome-wide to estimate the probability that individual results were due to chance. We identified a total of 12 putative susceptibility regions with per-family genome-wide probability < 0.05. These regions were located on 10 chromosomes; 10 of the 22 families showed linkage at these locations; two or more families showed linkage to 6 regions on 5 chromosomes (4q, 5q, 6p, 14q, 18p, and 18q). These results indicate that there is considerable heterogeneity among families in genomic regions and thus variants predisposing to breast cancer. Moreover, they suggest that uncommon high– or medium-risk genetic variants remain to be found, and that family designs can be an efficient way to identify them.

scholarly journals A novel activating JAK1 mutation in chronic eosinophilic leukemia

2021 ◽  
Vol 5 (18) ◽  
pp. 3581-3586 ◽  
Author(s):  
William Shomali ◽  
Alisa Damnernsawad ◽  
Talent Theparee ◽  
David Sampson ◽  
Quinlan Morrow ◽  
...  
Keyword(s):  
World Health ◽  
Variant Of Uncertain Significance ◽  
Jak2 Inhibitor ◽  
Functional Studies ◽  
Chronic Eosinophilic Leukemia ◽  
Uncertain Significance ◽  
Health Organization ◽  
Next Generation Sequencing Ngs ◽  
Stat Pathway

Abstract Hypereosinophilia (HE) has been defined as persistent eosinophilia &gt;1.5 × 109/L; it is broadly divided into primary HE (clonal or neoplastic; HEN), secondary/reactive HE (HER), or HE of undetermined significance (HEUS) when no cause is identified. The use of myeloid next-generation sequencing (NGS) panels has led to the detection of several mutations in patients previously diagnosed with HEUS, reassigning some patients to the category of HEN, specifically the World Health Organization category of chronic eosinophilic leukemia, not otherwise specified (CEL, NOS). Here, we describe a novel somatic JAK1 pseudokinase domain mutation (R629_S632delinsSA) in a patient with HE that had initially been characterized as a variant of uncertain significance. We performed functional studies that demonstrated that this mutation results in growth factor independence of Ba/F3 cells in vitro and activation of the JAK-STAT pathway. These effects were abrogated by the JAK1/JAK2 inhibitor ruxolitinib. R629_S632delinsSA is the first known somatic mutation in JAK1 linked to a clonal eosinophilic neoplasm, and highlights the importance of the JAK-STAT pathway in eosinophil survival.

scholarly journals Characterization of rare ABCC8 variants identified in Spanish pulmonary arterial hypertension patients

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Mauro Lago-Docampo ◽  
Jair Tenorio ◽  
Ignacio Hernández-González ◽  
Carmen Pérez-Olivares ◽  
Pilar Escribano-Subías ◽  
...  
Keyword(s):  
Pulmonary Arterial Hypertension ◽  
Arterial Hypertension ◽  
In Silico ◽  
Rare Variants ◽  
The Novel ◽  
Structural Protein ◽  
Uncertain Significance ◽  
Pulmonary Arterial ◽  
Biochemical Analyses

Abstract Pulmonary Arterial Hypertension (PAH) is a rare and fatal disease where knowledge about its genetic basis continues to increase. In this study, we used targeted panel sequencing in a cohort of 624 adult and pediatric patients from the Spanish PAH registry. We identified 11 rare variants in the ATP-binding Cassette subfamily C member 8 (ABCC8) gene, most of them with splicing alteration predictions. One patient also carried another variant in SMAD1 gene (c.27delinsGTAAAG). We performed an ABCC8 in vitro biochemical analyses using hybrid minigenes to confirm the correct mRNA processing of 3 missense variants (c.211C > T p.His71Tyr, c.298G > A p.Glu100Lys and c.1429G > A p.Val477Met) and the skipping of exon 27 in the novel splicing variant c.3394G > A. Finally, we used structural protein information to further assess the pathogenicity of the variants. The results showed 11 novel changes in ABCC8 and 1 in SMAD1 present in PAH patients. After in silico and in vitro biochemical analyses, we classified 2 as pathogenic (c.3288_3289del and c.3394G > A), 6 as likely pathogenic (c.211C > T, c.1429G > A, c.1643C > T, c.2422C > A, c.2694 + 1G > A, c.3976G > A and SMAD1 c.27delinsGTAAAG) and 3 as Variants of Uncertain Significance (c.298G > A, c.2176G > A and c.3238G > A). In all, we show that coupling in silico tools with in vitro biochemical studies can improve the classification of genetic variants.

scholarly journals Rare functional missense variants in CACNA1H: What can we learn from Writer’s cramp?

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Miaozhen Huang ◽  
Esther A. R. Nibbeling ◽  
Tjerk J. Lagrand ◽  
Ivana A. Souza ◽  
Justus L. Groen ◽  
...  
Keyword(s):  
Structural Changes ◽  
Neuronal Excitability ◽  
Rare Variants ◽  
Focal Dystonia ◽  
Functional Studies ◽  
Writer’S Cramp ◽  
Functional Variants ◽  
Writer's Cramp ◽  
Dutch Family

AbstractWriter’s cramp (WC) is a task-specific focal dystonia that occurs selectively in the hand and arm during writing. Previous studies have shown a role for genetics in the pathology of task-specific focal dystonia. However, to date, no causal gene has been reported for task-specific focal dystonia, including WC. In this study, we investigated the genetic background of a large Dutch family with autosomal dominant‒inherited WC that was negative for mutations in known dystonia genes. Whole exome sequencing identified 4 rare variants of unknown significance that segregated in the family. One candidate gene was selected for follow-up, Calcium Voltage-Gated Channel Subunit Alpha1 H, CACNA1H, due to its links with the known dystonia gene Potassium Channel Tetramerization Domain Containing 17, KCTD17, and with paroxysmal movement disorders. Targeted resequencing of CACNA1H in 82 WC cases identified another rare, putative damaging variant in a familial WC case that did not segregate. Using structural modelling and functional studies in vitro, we show that both the segregating p.Arg481Cys variant and the non-segregating p.Glu1881Lys variant very likely cause structural changes to the Cav3.2 protein and lead to similar gains of function, as seen in an accelerated recovery from inactivation. Both mutant channels are thus available for re-activation earlier, which may lead to an increase in intracellular calcium and increased neuronal excitability. Overall, we conclude that rare functional variants in CACNA1H need to be interpreted very carefully, and additional studies are needed to prove that the p.Arg481Cys variant is the cause of WC in the large Dutch family.

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