Imperial College London

DrPaulBarton

Faculty of MedicineNational Heart & Lung Institute

Honorary Senior Research Fellow
 
 
 
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Contact

 

+44 (0)20 7351 8140p.barton Website

 
 
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Location

 

2054Sydney StreetRoyal Brompton Campus

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Summary

 

Publications

Publication Type
Year
to

215 results found

Tayal U, gregson J, Buchan R, Whiffin N, Halliday B, Lota A, Roberts A, Baksi A, Voges I, Jarman J, Baruah R, Frenneaux M, Cleland J, Barton P, Pennell D, Ware J, Cook S, Prasad Set al., 2022, Moderate excess alcohol consumption and adverse cardiac remodelling in dilated cardiomyopathy, Heart, Vol: 108, Pages: 619-625, ISSN: 1355-6037

Objective The effect of moderate excess alcohol consumption is widely debated and has not been well defined in dilated cardiomyopathy (DCM). There is need for a greater evidence base to help advise patients. We sought to evaluate the effect of moderate excess alcohol consumption on cardiovascular structure, function and outcomes in DCM. Methods Prospective longitudinal observational cohort study. Patients with DCM (n=604) were evaluated for a history of moderate excess alcohol consumption (UK government guidelines; >14 units/week for women, >21 units/week for men) at cohort enrollment, had cardiovascular magnetic resonance and were followed up for the composite endpoint of cardiovascular death, heart failure and arrhythmic events. Patients meeting criteria for alcoholic cardiomyopathy were not recruited. ResultsDCM patients with a history of moderate excess alcohol consumption (n=98, 16%) had lower biventricular function and increased chamber dilatation of the left ventricle, right ventricle and left atrium, as well as increased left ventricular hypertrophy compared to patients without moderate alcohol consumption. They were more likely to be male (alcohol excess group– n =92, 94% vs n =306, 61%, p=<0.001). After adjustment for biological sex, moderate excess alcohol was not associated with adverse cardiac structure. There was no difference in mid-wall myocardial fibrosis between groups. Prior moderate excess alcohol consumption did not affect prognosis (HR 1.29, 0.73 to 2.26, p=0.38) during median follow up of 3.9 years. ConclusionDilated cardiomyopathy patients with moderate excess alcohol consumption have adverse cardiac structure and function at presentation but this is largely due to biological sex. Alcohol may contribute to sex-specific phenotypic differences in DCM. These findings help to inform lifestyle discussions for patients with dilated cardiomyopathy.

Journal article

Clerk A, Meijles DN, Hardyman MA, Fuller SJ, Chothani SP, Cull JJ, Cooper STE, Alharbi HO, Vanezis K, Felkin LE, Markou T, Leonard SJ, Shaw SW, Rackham OJL, Cook SA, Glennon PE, Sheppard MN, Sembrat JC, Rojas M, McTiernan CF, Barton PJ, Sugden PHet al., 2022, Cardiomyocyte BRAF and type 1 RAF inhibitors promote cardiomyocyte and cardiac hypertrophy in mice in vivo, Biochemical Journal, Vol: 479, Pages: 401-424, ISSN: 0264-6021

The extracellular signal-regulated kinase 1/2 (ERK1/2) cascade promotes cardiomyocyte hypertrophy and is cardioprotective, with the three RAF kinases forming a node for signal integration. Our aims were to determine if BRAF is relevant for human heart failure, whether BRAF promotes cardiomyocyte hypertrophy, and if Type 1 RAF inhibitors developed for cancer (that paradoxically activate ERK1/2 at low concentrations: the 'RAF paradox') may have the same effect. BRAF was up-regulated in heart samples from patients with heart failure compared with normal controls. We assessed the effects of activated BRAF in the heart using mice with tamoxifen-activated Cre for cardiomyocyte-specific knock-in of the activating V600E mutation into the endogenous gene. We used echocardiography to measure cardiac dimensions/function. Cardiomyocyte BRAFV600E induced cardiac hypertrophy within 10 d, resulting in increased ejection fraction and fractional shortening over 6 weeks. This was associated with increased cardiomyocyte size without significant fibrosis, consistent with compensated hypertrophy. The experimental Type 1 RAF inhibitor, SB590885, and/or encorafenib (a RAF inhibitor used clinically) increased ERK1/2 phosphorylation in cardiomyocytes, and promoted hypertrophy, consistent with a 'RAF paradox' effect. Both promoted cardiac hypertrophy in mouse hearts in vivo, with increased cardiomyocyte size and no overt fibrosis. In conclusion, BRAF potentially plays an important role in human failing hearts, activation of BRAF is sufficient to induce hypertrophy, and Type 1 RAF inhibitors promote hypertrophy via the 'RAF paradox'. Cardiac hypertrophy resulting from these interventions was not associated with pathological features, suggesting that Type 1 RAF inhibitors may be useful to boost cardiomyocyte function.

Journal article

Simoes Monteiro de Marvao A, McGurk K, Zheng S, Thanaj M, Bai W, Duan J, Biffi C, Mazzarotto F, Statton B, Dawes T, Savioli N, Halliday B, Xu X, Buchan R, Baksi A, Quinlan M, Tokarczuk P, Tayal U, Francis C, Whiffin N, Theotokis A, Zhang X, Jang M, Berry A, Pantazis A, Barton P, Rueckert D, Prasad S, Walsh R, Ho C, Cook S, Ware J, O'Regan Det al., 2021, Phenotypic expression and outcomes in individuals with rare genetic variants of hypertrophic cardiomyopathy, Journal of the American College of Cardiology, Vol: 78, Pages: 1097-1110, ISSN: 0735-1097

Background: Hypertrophic cardiomyopathy (HCM) is caused by rare variants in sarcomereencoding genes, but little is known about the clinical significance of these variants in thegeneral population.Objectives: To compare lifetime outcomes and cardiovascular phenotypes according to thepresence of rare variants in sarcomere-encoding genes amongst middle-aged adults.Methods: We analysed whole exome sequencing and cardiac magnetic resonance (CMR)imaging in UK Biobank participants stratified by sarcomere-encoding variant status.Results: The prevalence of rare variants (allele frequency <0.00004) in HCM-associatedsarcomere-encoding genes in 200,584 participants was 2.9% (n=5,712; 1 in 35), and theprevalence of variants pathogenic or likely pathogenic for HCM (SARC-HCM-P/LP) was0.25% (n=493, 1 in 407). SARC-HCM-P/LP variants were associated with increased risk ofdeath or major adverse cardiac events compared to controls (HR 1.69, 95% CI 1.38 to 2.07,p<0.001), mainly due to heart failure endpoints (HR 4.23, 95% CI 3.07 to 5.83, p<0.001). In21,322 participants with CMR, SARC-HCM-P/LP were associated with asymmetric increasein left ventricular maximum wall thickness (10.9±2.7 vs 9.4±1.6 mm, p<0.001) buthypertrophy (≥13mm) was only present in 18.4% (n=9/49, 95% CI 9 to 32%). SARC-HCMP/LP were still associated with heart failure after adjustment for wall thickness (HR 6.74,95% CI 2.43 to 18.7, p<0.001).Conclusions: In this population of middle-aged adults, SARC-HCM-P/LP variants have lowaggregate penetrance for overt HCM but are associated with increased risk of adversecardiovascular outcomes and an attenuated cardiomyopathic phenotype. Although absoluteevent rates are low, identification of these variants may enhance risk stratification beyondfamilial disease.

Journal article

Aguib Y, Allouba M, Walsh R, Ibrahim AM, Halawa S, Afify A, Hosny M, Theotokis PI, Galal A, Elshorbagy S, Roshdy M, Kassem HS, Ellithy A, Buchan R, Whiffin N, Anwer S, Cook S, Moustafa A, ElGuindy A, Ware J, Barton P, Yacoub Met al., 2021, New variant with a previously unrecognized mechanism of pathogenicity in hypertrophic cardiomyopathy, Circulation, Vol: 144, Pages: 754-757, ISSN: 0009-7322

Journal article

Patel PN, Ito K, Willcox JAL, Haghighi A, Jang MY, Gorham JM, DePalma SR, Lam L, McDonough B, Johnson R, Lakdawala NK, Roberts A, Barton PJR, Cook SA, Fatkin D, Seidman CE, Seidman JGet al., 2021, Contribution of noncanonical splice variants to TTN truncating variants cardiomyopathy, Circulation: Genomic and Precision Medicine, Vol: 14, Pages: 1-10, ISSN: 2574-8300

Background:Heterozygous TTN truncating variants cause 10% to 20% of idiopathic dilated cardiomyopathy (DCM). Although variants which disrupt canonical splice signals (ie, invariant dinucleotide of splice donor site, invariant dinucleotide of the splice acceptor site) at exon-intron junctions are readily recognized as TTN truncating variants, the effects of other nearby sequence variations on splicing and their contribution to disease is uncertain.Methods:Rare variants of unknown significance located in the splice regions of highly expressed TTN exons from 203 DCM cases, 3329 normal subjects, and clinical variant databases were identified. The effects of these variants on splicing were assessed using an in vitro splice assay.Results:Splice-altering variants of unknown significance were enriched in DCM cases over controls and present in 2% of DCM patients (P=0.002). Application of this method to clinical variant databases demonstrated 20% of similar variants of unknown significance in TTN splice regions affect splicing. Noncanonical splice-altering variants were most frequently located at position +5 of the donor site (P=4.4×107) and position -3 of the acceptor site (P=0.002). SpliceAI, an emerging in silico prediction tool, had a high positive predictive value (86%–95%) but poor sensitivity (15%–50%) for the detection of splice-altering variants. Alternate exons spliced out of most TTN transcripts frequently lacked the consensus base at +5 donor and −3 acceptor positions.Conclusions:Noncanonical splice-altering variants in TTN explain 1-2% of DCM and offer a 10-20% increase in the diagnostic power of TTN sequencing in this disease. These data suggest rules that may improve efforts to detect splice-altering variants in other genes and may explain the low percent splicing observed for many alternate TTN exons.

Journal article

Wright CF, Quaife NM, Ramos-Hernández L, Danecek P, Ferla MP, Samocha KE, Kaplanis J, Gardner EJ, Eberhardt RY, Chao KR, Karczewski KJ, Morales J, Gallone G, Balasubramanian M, Banka S, Gompertz L, Kerr B, Kirby A, Lynch SA, Morton JEV, Pinz H, Sansbury FH, Stewart H, Zuccarelli BD, Genomics England Research Consortium, Cook SA, Taylor JC, Juusola J, Retterer K, Firth HV, Hurles ME, Lara-Pezzi E, Barton PJR, Whiffin Net al., 2021, Non-coding region variants upstream of MEF2C cause severe developmental disorder through three distinct loss-of-function mechanisms, American Journal of Human Genetics, Vol: 108, Pages: 1083-1094, ISSN: 0002-9297

Clinical genetic testing of protein-coding regions identifies a likely causative variant in only around half of developmental disorder (DD) cases. The contribution of regulatory variation in non-coding regions to rare disease, including DD, remains very poorly understood. We screened 9,858 probands from the Deciphering Developmental Disorders (DDD) study for de novo mutations in the 5' untranslated regions (5' UTRs) of genes within which variants have previously been shown to cause DD through a dominant haploinsufficient mechanism. We identified four single-nucleotide variants and two copy-number variants upstream of MEF2C in a total of ten individual probands. We developed multiple bespoke and orthogonal experimental approaches to demonstrate that these variants cause DD through three distinct loss-of-function mechanisms, disrupting transcription, translation, and/or protein function. These non-coding region variants represent 23% of likely diagnoses identified in MEF2C in the DDD cohort, but these would all be missed in standard clinical genetics approaches. Nonetheless, these variants are readily detectable in exome sequence data, with 30.7% of 5' UTR bases across all genes well covered in the DDD dataset. Our analyses show that non-coding variants upstream of genes within which coding variants are known to cause DD are an important cause of severe disease and demonstrate that analyzing 5' UTRs can increase diagnostic yield. We also show how non-coding variants can help inform both the disease-causing mechanism underlying protein-coding variants and dosage tolerance of the gene.

Journal article

Whiffin N, Karczewski KJ, Zhang X, Chothani S, Smith MJ, Evans DG, Roberts AM, Quaife NM, Schafer S, Rackham O, Alfoeldi J, O'Donnell-Luria AH, Francioli LC, Armean IM, Aguilar Salinas CA, Cook SA, Barton PJR, MacArthur DG, Ware JSet al., 2021, Characterising the loss-of-function impact of 5 ' untranslated region variants in 15,708 individuals (vol 11, 2523, 2020), Nature Communications, Vol: 12, Pages: 1-1, ISSN: 2041-1723

Journal article

Mazzarotto F, Hawley MH, Beltrami M, Beekman L, De Marvao A, McGurk K, Statton B, Boschi B, Girolami F, Roberts AM, Lodder EM, Allouba M, Romeih S, Aguib Y, Baksi J, Pantazis A, Prasad SK, Cerbai E, Yacoub M, O'Regan D, Cook S, Ware J, Funke B, Olivotto I, Bezzina C, Barton P, Walsh Ret al., 2021, Systematic large-scale assessment of the genetic architecture of left ventricular non-compaction reveals diverse aetiologies, Genetics in Medicine, Vol: 23, Pages: 856-864, ISSN: 1098-3600

Purpose: To characterise the genetic architecture of left ventricular non-compaction (LVNC) and investigate the extent to which it may represent a distinct pathology or a secondary phenotype associated with other cardiac diseases.Methods: We performed rare variant association analysis with 840 LVNC cases and 125,748 gnomAD population controls, and compared results to similar analyses on dilated cardiomyopathy (DCM) and hypertrophic cardiomyopathy (HCM). Results: We observed substantial genetic overlap indicating that LVNC often represents a phenotypic variation of DCM or HCM. In contrast, truncating variants (TV) in MYH7, ACTN2 and PRDM16 were uniquely associated with LVNC and may reflect a distinct LVNC aetiology. In particular, MYH7 TV, generally considered non-pathogenic for cardiomyopathies, were 20-fold enriched in LVNC cases over controls. MYH7 TV heterozygotes identified in the UK Biobank and healthy volunteer cohorts also displayed significantly greater non-compaction compared to matched controls. RYR2 exon deletions and HCN4 transmembrane variants were also enriched in LVNC, supporting prior reports of association with arrhythmogenic LVNC phenotypes.Conclusions: LVNC is characterised by substantial genetic overlap with DCM/HCM but is also associated with distinct non-compaction and arrhythmia aetiologies. These results will enable enhanced application of LVNC genetic testing and help to distinguish pathological from physiological non-compaction.

Journal article

de Marvao A, McGurk KA, Zheng SL, Thanaj M, Bai W, Duan J, Biffi C, Mazzarotto F, Statton B, Dawes TJW, Savioli N, Halliday BP, Xu X, Buchan RJ, Baksi AJ, Quinlan M, Tokarczuk P, Tayal U, Francis C, Whiffin N, Theotokis PI, Zhang X, Jang M, Berry A, Pantazis A, Barton PJR, Rueckert D, Prasad SK, Walsh R, Ho CY, Cook SA, Ware JS, ORegan DPet al., 2021, Outcomes and phenotypic expression of rare variants in hypertrophic cardiomyopathy genes amongst UK Biobank participants, Publisher: Cold Spring Harbor Laboratory

<jats:title>Abstract</jats:title><jats:sec><jats:title>Background</jats:title><jats:p>Hypertrophic cardiomyopathy (HCM) is caused by rare variants in sarcomere-encoding genes, but little is known about the clinical significance of these variants in the general population.</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>We compared outcomes and cardiovascular phenotypes in UK Biobank participants with whole exome sequencing stratified by sarcomere-encoding variant status.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>The prevalence of rare variants (allele frequency &lt;0.00004) in HCM-associated sarcomere-encoding genes in 200,584 participants was 2.9% (n=5,727; 1 in 35), of which 0.24% (n=474, 1 in 423) were pathogenic or likely pathogenic variants (SARC-P/LP). SARC-P/LP variants were associated with increased risk of death or major adverse cardiac events compared to controls (HR 1.68, 95% CI 1.37-2.06, p&lt;0.001), mainly due to heart failure (HR 4.40, 95% CI 3.22-6.02, p&lt;0.001) and arrhythmia (HR 1.55, 95% CI 1.18-2.03, p=0.002). In 21,322 participants with cardiac magnetic resonance imaging, SARC-P/LP were associated with increased left ventricular maximum wall thickness (10.9±2.7 vs 9.4±1.6 mm, p&lt;0.001) and concentric remodelling (mass/volume ratio: 0.63±0.12 vs 0.58±0.09 g/mL, p&lt;0.001), but hypertrophy (≥13mm) was only present in 16% (n=7/43, 95% CI 7-31%). Other rare sarcomere-encoding variants had a weak effect on wall thickness (9.5±1.7 vs 9.4±1.6 mm, p=0.002) with no combined excess cardiovascular risk (HR 1.00 95% CI 0.92-1.08, p=0.9).</jats:p></jats:sec><jats:sec><jats:title>Conclusions</jats:title><jats:p>In the general population, SARC-P/LP variants have low aggregate penetrance for overt HCM bu

Working paper

Ware J, Tadros R, Francis C, Xu X, Matthews P, watkins H, Bezzina Cet al., 2021, Shared genetic pathways contribute to risk of hypertrophic and dilated cardiomyopathies with opposite directions of effect, Nature Genetics, Vol: 53, Pages: 128-134, ISSN: 1061-4036

The heart muscle diseases hypertrophic (HCM) and dilated (DCM) cardiomyopathies are leading causes of sudden death and heart failure in young otherwise healthy individuals. We conducted genome-wide association studies (GWAS) and multi-trait analyses in HCM (1,733 cases), DCM (5,521 cases), and nine left ventricular (LV) traits in 19,260 UK Biobank participants with structurally-normal hearts. We identified 16 loci associated with HCM, 13 with DCM, and 23 with LV traits. We show strong genetic correlations between LV traits and cardiomyopathies, with opposing effects in HCM and DCM. Two-sample Mendelian randomization supports a causal association linking increased contractility with HCM risk. A polygenic risk score (PRS) explains a significant portion of phenotypic variability in carriers of HCM-causing rare variants. Our findings thus provide evidence that PRS may account for variability in Mendelian diseases. More broadly, we provide insights into how genetic pathways may lead to distinct disorders through opposing genetic effects.

Journal article

Zhang X, Walsh R, Whiffin N, Buchan R, Midwinter W, Wilk A, Govind R, Li N, Ahmad M, Mazzarotto F, Roberts A, Theotokis P, Mazaika E, Allouba M, de Marvao A, Pua CJ, Day SM, Ashley E, Colan SD, Michels M, Pereira AC, Jacoby D, Ho CY, Olivotto I, Gunnarsson GT, Jefferies J, Semsarian C, Ingles J, ORegan DP, Aguib Y, Yacoub MH, Cook SA, Barton PJR, Bottolo L, Ware JSet al., 2021, Disease-specific variant pathogenicity prediction significantly improves variant interpretation in inherited cardiac conditions, Genetics in Medicine, Vol: 23, Pages: 69-79, ISSN: 1098-3600

Background: Accurate discrimination of benign and pathogenic rare variation remains a priority for clinical genome interpretation. State-of-the-art machine learning tools are useful for genome-wide variant prioritisation but remain imprecise. Since the relationship between molecular consequence and likelihood of pathogenicity varies between genes with distinct molecular mechanisms, we hypothesised that a disease-specific classifier may outperform existing genome-wide tools. Methods: We present a novel disease-specific variant classification tool, CardioBoost, that estimates the probability of pathogenicity for rare missense variants in inherited cardiomyopathies and arrhythmias, trained with variants of known clinical effect. To benchmark against state-of-the-art genome-wide pathogenicity classification tools, we assessed classification of hold-out test variants using both overall performance metrics, and metrics of high-confidence (&gt;90%) classifications relevant to variant interpretation. We further evaluated the prioritisation of variants associated with disease and patient clinical outcomes, providing validations that are robust to potential mis-classification in gold-standard reference datasets.Results: CardioBoost has higher discriminating power than published genome-wide variant classification tools in distinguishing between pathogenic and benign variants based on overall classification performance measures with the highest area under the Precision-Recall Curve as 91% for cardiomyopathies and as 96% for inherited arrhythmias. When assessed at high-confidence (&gt;90%) classification thresholds, prediction accuracy is improved by at least 120% over existing tools for both cardiomyopathies and arrhythmias, with significantly improved sensitivity and specificity. Finally, CardioBoost improves prioritisation of variants significantly associated with disease, and stratifies survival of patients with cardiomyopathies, confirming biologically relevant vari

Journal article

Whiffin N, Karczewski KJ, Zhang X, Chothani S, Smith MJ, Evans DG, Roberts AM, Quaife NM, Schafer S, Rackham O, Alföldi J, ODonnell-Luria AH, Francioli LC, Alföldi J, Armean IM, Banks E, Bergelson L, Cibulskis K, Collins RL, Connolly KM, Covarrubias M, Cummings B, Daly MJ, Donnelly S, Farjoun Y, Ferriera S, Francioli L, Gabriel S, Gauthier LD, Gentry J, Gupta N, Jeandet T, Kaplan D, Karczewski KJ, Laricchia KM, Llanwarne C, Minikel EV, Munshi R, Neale BM, Novod S, ODonnell-Luria AH, Petrillo N, Poterba T, Roazen D, Ruano-Rubio V, Saltzman A, Samocha KE, Schleicher M, Seed C, Solomonson M, Soto J, Tiao G, Tibbetts K, Tolonen C, Vittal C, Wade G, Wang A, Wang Q, Ware JS, Watts NA, Weisburd B, Whiffin N, Salinas CAA, Ahmad T, Albert CM, Ardissino D, Atzmon G, Barnard J, Beaugerie L, Benjamin EJ, Boehnke M, Bonnycastle LL, Bottinger EP, Bowden DW, Bown MJ, Chambers JC, Chan JC, Chasman D, Cho J, Chung MK, Cohen B, Correa A, Dabelea D, Daly MJ, Darbar D, Duggirala R, Dupuis J, Ellinor PT, Elosua R, Erdmann J, Esko T, Färkkilä M, Florez J, Franke A, Getz G, Glaser B, Glatt SJ, Goldstein D, Gonzalez C, Groop L, Haiman C, Hanis C, Harms M, Hiltunen M, Holi MM, Hultman CM, Kallela M, Kaprio J, Kathiresan S, Kim B-J, Kim YJ, Kirov G, Kooner J, Koskinen S, Krumholz HM, Kugathasan S, Kwak SH, Laakso M, Lehtimäki T, Loos RJF, Lubitz SA, Ma RCW, MacArthur DG, Marrugat J, Mattila KM, McCarroll S, McCarthy MI, McGovern D, McPherson R, Meigs JB, Melander O, Metspalu A, Neale BM, Nilsson PM, ODonovan MC, Ongur D, Orozco L, Owen MJ, Palmer CNA, Palotie A, Park KS, Pato C, Pulver AE, Rahman N, Remes AM, Rioux JD, Ripatti S, Roden DM, Saleheen D, Salomaa V, Samani NJ, Scharf J, Schunkert H, Shoemaker MB, Sklar P, Soininen H, Soko H, Spector T, Sullivan PF, Suvisaari J, Tai ES, Teo YY, Tiinamaija T, Tsuang M, Turner D, Tusie-Luna T, Vartiainen E, Ware JS, Watkins H, Weersma RK, Wessman M, Wilson JG, Xavier RJ, Cook SA, Barton PJR, MacArthur DG, Ware JSet al., 2020, Characterising the loss-of-function impact of 5’ untranslated region variants in whole genome sequence data from 15,708 individuals, Nature Communications, Vol: 11

<jats:title>Abstract</jats:title><jats:p>Upstream open reading frames (uORFs) are important tissue-specific <jats:italic>cis</jats:italic>-regulators of protein translation. Although isolated case reports have shown that variants that create or disrupt uORFs can cause disease, genetic sequencing approaches typically focus on protein-coding regions and ignore these variants. Here, we describe a systematic genome-wide study of variants that create and disrupt human uORFs, and explore their role in human disease using 15,708 whole genome sequences collected by the Genome Aggregation Database (gnomAD) project. We show that 14,897 variants that create new start codons upstream of the canonical coding sequence (CDS), and 2,406 variants disrupting the stop site of existing uORFs, are under strong negative selection. Furthermore, variants creating uORFs that overlap the CDS show signals of selection equivalent to coding loss-of-function variants, and uORF-perturbing variants are under strong selection when arising upstream of known disease genes and genes intolerant to loss-of-function variants. Finally, we identify specific genes where perturbation of uORFs is likely to represent an important disease mechanism, and report a novel uORF frameshift variant upstream of <jats:italic>NF2</jats:italic> in families with neurofibromatosis. Our results highlight uORF-perturbing variants as an important and under-recognised functional class that can contribute to penetrant human disease, and demonstrate the power of large-scale population sequencing data to study the deleteriousness of specific classes of non-coding variants.</jats:p>

Journal article

Aguib Y, Allouba M, Afify A, Halawa S, El-Khatib M, Sous M, Galal A, Abdelrahman E, Shehata N, El Sawy A, Elmaghawry M, Anwer S, Kamel O, El Mozy W, Khedr H, Kharabish A, Thabet N, Theotokis P, Buchan R, Govind R, Whiffin N, Walsh R, Aguib H, ElGuindy A, O'Regan D, Cook S, Barton P, Ware J, Yacoub Met al., 2020, The Egyptian collaborative cardiac genomics (ECCO-GEN) Project: defining a healthy volunteer cohort, npj Genomic Medicine, Vol: 5, Pages: 1-8, ISSN: 2056-7944

The integration of comprehensive genomic and phenotypic data from diverse ethnic populations offers unprecedented opportunities towards advancements in precision medicine and novel diagnostic technologies. Current reference genomic databases are not representative of the global human population, making variant interpretation challenging, especially in underrepresented populations such as the North African population. To address this, the Egyptian Collaborative Cardiac Genomics (ECCO-GEN) Project launched a study comprising 1,000 individuals free of cardiovascular disease (CVD). Here, we present the first 391 Egyptian healthy volunteers (EHVols) recruited to establish a pilot phenotyped control cohort. All individuals underwent detailed clinical investigation, including cardiac MRI, and were sequenced using a targeted panel of 174 genes with reported roles in inherited cardiac conditions (ICC). We identified 1,262 variants in 27 cardiomyopathy genes of which 15.1% were not captured in current global and regional genetic reference databases (here: gnomAD and Great Middle Eastern (GME) Variome). The ECCO-GEN project aims at defining the genetic landscape of an understudied population and providing individual-level genetic and phenotypic data to support future studies in CVD and population genetics.

Journal article

Pua CJ, Tham N, Chin CW, Walsh R, Khor CC, Toepfer CN, Repetti GG, Garfinkel AC, Ewoldt JF, Cloonan P, Chen CS, Lim SQ, Cai J, Loo LY, Kong SC, Chiang CWK, Whiffin N, de Marvao A, Lio PM, Hii AA, Yang CX, Le TT, Bylstra Y, Lim WK, Teo JX, Padilha K, Venturini G, Pan B, Govind R, Buchan RJ, Barton PJ, Tan P, Foo R, Yip JWL, Wong RCC, Chan WX, Pereira AC, Tang HC, Jamuar SS, Ware JS, Seidman JG, Seidman CE, Cook SAet al., 2020, Genetic studies of hypertrophic cardiomyopathy in Singaporeans identify variants in TNNI3 and TNNT2 that are common in Chinese patients, Circulation: Genomic and Precision Medicine, Vol: 13, Pages: 424-434, ISSN: 2574-8300

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=3,634), compared findings with additional populations and Caucasian HCM cohorts (n=6,179) and performed in vitro functional studies.Results - Singaporean HCM patients had significantly fewer confidently interpreted HCM disease variants (Pathogenic (P)/Likely Pathogenic (LP):18%, p<0.0001) but an excess of variants of unknown significance (exVUS: 24%, p<0.0001), as compared to Caucasians (P/LP: 31%, exVUS: 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, gnomAD-East Asian (gnomAD-EA) AF=0.0062, p=0.0086; TNNT2:p.R286H, Singaporean controls AF=0.0017, p<0.0001, gnomAD-EA 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 to non-carriers while its etiological fraction is limited (0.70, 95% CI: 0.35-0.86) and thus TNNI3:p.R79C is considered a VUS. Mutant TNNT2:p.R286H iPSC-CMs 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 to Caucasians, 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-Caucasian pop

Journal article

Lopez-Sainz A, Dominguez F, Rocha Lopes L, Pablo Ochoa J, Barriales-Villa R, Climent V, Linschoten M, Tiron C, Chiriatti C, Marques N, Rasmussen TB, Angeles Espinosa M, Beinart R, Quarta G, Cesar S, Field E, Garcia-Pinilla JM, Bilinska Z, Muir AR, Roberts AM, Santas E, Zorio E, Pena-Pena ML, Navarro M, Fernandez A, Palomino-Doza J, Azevedo O, Lorenzini M, Garcia-Alvarez MI, Bento D, Jensen MK, Mendez I, Pezzoli L, Sarquella-Brugada G, Campuzano O, Gonzalez-Lopez E, Mogensen J, Kaski JP, Arad M, Brugada R, Asselbergs FW, Monserrat L, Olivotto I, Elliott PM, Garcia-Pavia Pet al., 2020, Clinical features and natural history of PRKAG2 variant cardiac glycogenosis, Journal of the American College of Cardiology, Vol: 76, Pages: 186-197, ISSN: 0735-1097

BackgroundPRKAG2 gene variants cause a syndrome characterized by cardiomyopathy, conduction disease, and ventricular pre-excitation. Only a small number of cases have been reported to date, and the natural history of the disease is poorly understood.ObjectivesThe aim of this study was to describe phenotype and natural history of PRKAG2 variants in a large multicenter European cohort.MethodsClinical, electrocardiographic, and echocardiographic data from 90 subjects with PRKAG2 variants (53% men; median age 33 years; interquartile range [IQR]: 15 to 50 years) recruited from 27 centers were retrospectively studied.ResultsAt first evaluation, 93% of patients were in New York Heart Association functional class I or II. Maximum left ventricular wall thickness was 18 ± 8 mm, and left ventricular ejection fraction was 61 ± 12%. Left ventricular hypertrophy (LVH) was present in 60 subjects (67%) at baseline. Thirty patients (33%) had ventricular pre-excitation or had undergone accessory pathway ablation; 17 (19%) had pacemakers (median age at implantation 36 years; IQR: 27 to 46 years), and 16 (18%) had atrial fibrillation (median age 43 years; IQR: 31 to 54 years). After a median follow-up period of 6 years (IQR: 2.3 to 13.9 years), 71% of subjects had LVH, 29% had AF, 21% required de novo pacemakers (median age at implantation 37 years; IQR: 29 to 48 years), 14% required admission for heart failure, 8% experienced sudden cardiac death or equivalent, 4% required heart transplantation, and 13% died.ConclusionsPRKAG2 syndrome is a progressive cardiomyopathy characterized by high rates of atrial fibrillation, conduction disease, advanced heart failure, and life-threatening arrhythmias. Classical features of pre-excitation and severe LVH are not uniformly present, and diagnosis should be considered in patients with LVH who develop atrial fibrillation or require permanent pacemakers at a young age.

Journal article

Mazzarotto F, Olivotto I, Boschi B, Girolami F, Poggesi C, Barton P, Walsh Ret al., 2020, Contemporary insights into the genetics of hypertrophic cardiomyopathy: towards a new era in clinical testing?, Journal of the American Heart Association, Vol: 21, Pages: 1-22, ISSN: 2047-9980

Genetic testing for hypertrophic cardiomyopathy (HCM) is an established clinical technique, supported by30 years of research into its genetic aetiology. Although pathogenic variants are often detected in patientsand used to identify at-risk relatives, the effectiveness of genetic testing has been hampered by ambiguousgenetic associations (yielding uncertain and potentially false-positive results), difficulties in classifyingvariants and uncertainty about genotype-negative patients. Recent case-control studies on rare variation,improved data sharing and meta-analysis of case cohorts contributed to new insights into the genetic basisof HCM. In particular, while research into new genes and mechanisms remains essential, re-assessment ofMendelian genetic associations in HCM argues that current clinical genetic testing should be limited to asmall number of validated disease genes that yield informative and interpretable results. Accurate andconsistent variant interpretation has benefitted from new standardised variant interpretation guidelines andinnovative approaches to improve classification. Most cases lacking a pathogenic variant are now believedto indicate non-Mendelian HCM, with more benign prognosis and minimal risk to relatives.Here, we discuss recent advances in the genetics of HCM and their application to clinical genetic testingtogether with practical issues regarding implementation. While this review focuses on HCM, many of theissues discussed are also relevant to other inherited cardiac diseases.

Journal article

Allouba M, Aguib Y, Walsh R, Afify A, Theotokis P, Galal A, Halawa S, Shorbagy S, Ibrahim AM, Kassem HS, Ellithy A, Buchan R, Hosny M, Whiffin N, Elguindy A, Anwer S, Cook SA, Ware JS, Barton PJ, Yacoub Met al., 2020, Analysis of HCM in an understudied population reveals a new mechanism of pathogenicity, Publisher: Cold Spring Harbor Laboratory

Hypertrophic Cardiomyopathy (HCM) is an inherited disease characterized by genetic and phenotypic heterogeneity. MYH7 represents one of the main sarcomere-encoding genes associated with HCM. Missense variants in this gene cause HCM through gain-of-function actions, whereby variants produce an abnormal activated protein which incorporates into the sarcomere as a "poison peptide". Here we report a frameshift variant in MYH7, c.5769delG, that is associated with HCM in an Egyptian cohort (3.3%) compared with ethnically-matched controls. This variant is absent from previously published large-scale Caucasian HCM cohorts. We further demonstrate strong evidence of co-segregation of c.5769delG with HCM in a large family (LOD score: 3.01). The predicted sequence of the variant MYH7 transcript shows that the frameshift results in a premature termination codon (PTC) downstream of the last exon-exon junction of the gene that is expected to escape nonsense-mediated decay (NMD). RNA sequencing of myocardial tissue obtained from a patient with the variant during surgical myectomy confirmed the expression of the variant MYH7 transcript. Our analysis reveals a new mechanism of pathogenicity in the understudied Egyptian population whereby distal PTC in MYH7 may lead to the expression of an abnormal protein.

Working paper

Mazzarotto F, Tayal U, Buchan RJ, Midwinter W, Wilk A, Whiffin N, Govind R, Mazaika E, de Marvao A, Dawes TJW, Felkin LE, Ahmad M, Theotokis PI, Edwards E, Ing AY, Thomson KL, Chan LLH, Sim D, Baksi AJ, Pantazis A, Roberts AM, Watkins H, Funke B, O'Regan DP, Olivotto I, Barton PJR, Prasad SK, Cook SA, Ware JS, Walsh Ret al., 2020, Reevaluating the Genetic Contribution of Monogenic Dilated Cardiomyopathy., Circulation, Vol: 141, Pages: 387-398

BACKGROUND: Dilated cardiomyopathy (DCM) is genetically heterogeneous, with >100 purported disease genes tested in clinical laboratories. However, many genes were originally identified based on candidate-gene studies that did not adequately account for background population variation. Here we define the frequency of rare variation in 2538 patients with DCM across protein-coding regions of 56 commonly tested genes and compare this to both 912 confirmed healthy controls and a reference population of 60 706 individuals to identify clinically interpretable genes robustly associated with dominant monogenic DCM. METHODS: We used the TruSight Cardio sequencing panel to evaluate the burden of rare variants in 56 putative DCM genes in 1040 patients with DCM and 912 healthy volunteers processed with identical sequencing and bioinformatics pipelines. We further aggregated data from 1498 patients with DCM sequenced in diagnostic laboratories and the Exome Aggregation Consortium database for replication and meta-analysis. RESULTS: Truncating variants in TTN and DSP were associated with DCM in all comparisons. Variants in MYH7, LMNA, BAG3, TNNT2, TNNC1, PLN, ACTC1, NEXN, TPM1, and VCL were significantly enriched in specific patient subsets, with the last 2 genes potentially contributing primarily to early-onset forms of DCM. Overall, rare variants in these 12 genes potentially explained 17% of cases in the outpatient clinic cohort representing a broad range of adult patients with DCM and 26% of cases in the diagnostic referral cohort enriched in familial and early-onset DCM. Although the absence of a significant excess in other genes cannot preclude a limited role in disease, such genes have limited diagnostic value because novel variants will be uninterpretable and their diagnostic yield is minimal. CONCLUSIONS: In the largest sequenced DCM cohort yet described, we observe robust disease association with 12 genes, highlighting their importance in DCM and translating in

Journal article

Chothani S, Schäfer S, Adami E, Viswanathan S, Widjaja AA, Langley SR, Tan J, Wang M, Quaife NM, Pua CJ, D'Agostino G, Shekeran SG, George BL, Lim S, Cao EY, van Heesch S, Witte F, Felkin LE, Christodoulou EG, Dong J, Blachut S, Patone G, Barton PJR, Hubner N, Cook SA, Rackham OJLet al., 2019, Widespread translational control of fibrosis in the human heart by RNA-binding proteins, Circulation, Vol: 140, Pages: 937-951, ISSN: 0009-7322

BACKGROUND: Fibrosis is a common pathology in many cardiac disorders and is driven by the activation of resident fibroblasts. The global post-transcriptional mechanisms underlying fibroblast-to-myofibroblast conversion in the heart have not been explored. METHODS: Genome-wide changes of RNA transcription and translation during human cardiac fibroblast activation were monitored with RNA sequencing and ribosome profiling. We then used an RNA-binding protein-based analyses to identify translational regulators of fibrogenic genes. The integration with cardiac ribosome occupancy levels of 30 dilated cardiomyopathy patients demonstrates that these post-transcriptional mechanisms are also active in the diseased fibrotic human heart. RESULTS: We generated nucleotide-resolution translatome data during the TGFβ1-driven cellular transition of human cardiac fibroblasts to myofibroblasts. This identified dynamic changes of RNA transcription and translation at several time points during the fibrotic response, revealing transient and early-responder genes. Remarkably, about one-third of all changes in gene expression in activated fibroblasts are subject to translational regulation and dynamic variation in ribosome occupancy affects protein abundance independent of RNA levels. Targets of RNA-binding proteins were strongly enriched in post-transcriptionally regulated genes, suggesting genes such as MBNL2 can act as translational activators or repressors. Ribosome occupancy in the hearts of patients with dilated cardiomyopathy suggested the same post-transcriptional regulatory network was underlying cardiac fibrosis. Key network hubs include RNA-binding proteins such as PUM2 and QKI that work in concert to regulate the translation of target transcripts in human diseased hearts. Furthermore, silencing of both PUM2 and QKI inhibits the transition of fibroblasts toward pro-fibrotic myofibroblasts in response to TGFβ1. CONCLUSIONS: We reveal widespread translational effects of

Journal article

Chen H, Moreno-Moral A, Pesce F, Devapragash N, Mancini M, Heng EL, Rotival M, Srivastava PK, Harmston N, Shkura K, Rackham OJL, Yu W-P, Sun X-M, Tee NGZ, Tan ELS, Barton PJR, Felkin LE, Lara-Pezzi E, Angelini G, Beltrami C, Pravenec M, Schafer S, Bottolo L, Hubner N, Emanueli C, Cook SA, Petretto Eet al., 2019, Author Correction: WWP2 regulates pathological cardiac fibrosis by modulating SMAD2 signaling, Nature Communications, Vol: 10, ISSN: 2041-1723

Journal article

Chen H, Moreno-Moral A, Pesce F, Devapragash N, Mancini M, Heng E, Rotival M, Srivastava P, Harmston N, Shkura K, Rackham O, Yu W-P, Sun X-M, Gui Zhen Tee N, Tan E, Barton P, Felkin L, Lara-Pezzi E, Angelini G, Beltrami C, Pravenec M, Schafer S, Bottolo L, Hubner N, Emanueli C, Cook S, Petretto Eet al., 2019, WWP2 regulates pathological cardiac fibrosis by modulating SMAD2 signaling, Nature Communications, Vol: 10, Pages: 1-19, ISSN: 2041-1723

Cardiac fibrosis is a final common pathology in inherited and acquired heart diseases that causes cardiac electrical and pump failure. Here, we use systems genetics to identify a pro-fibrotic gene network in the diseased heart and show that this network is regulated by the E3 ubiquitin ligase WWP2, specifically by the WWP2-N terminal isoform. Importantly, the WWP2-regulated pro-fibrotic gene network is conserved across different cardiac diseases characterized by fibrosis: human and murine dilated cardiomyopathy and repaired tetralogy of Fallot. Transgenic mice lacking the N-terminal region of the WWP2 protein show improved cardiac function and reduced myocardial fibrosis in response to pressure overload or myocardial infarction. In primary cardiac fibroblasts, WWP2 positively regulates the expression of pro-fibrotic markers and extracellular matrix genes. TGFβ1 stimulation promotes nuclear translocation of the WWP2 isoforms containing the N-terminal region and their interaction with SMAD2. WWP2 mediates the TGFβ1-induced nucleocytoplasmic shuttling and transcriptional activity of SMAD2.

Journal article

Garcia-Pavia P, Kim Y, Restrepo-Cordoba MA, Lunde IG, Wakimoto H, Smith AM, Toepfer CN, Getz K, Gorham J, Patel P, Ito K, Willcox JA, Arany Z, Li J, Owens AT, Govind R, Nuñez B, Mazaika E, Bayes-Genis A, Walsh R, Finkelman B, Lupon J, Whiffin N, Serrano I, Midwinter W, Wilk A, Bardaji A, Ingold N, Buchan R, Tayal U, Pascual-Figal DA, de Marvao A, Ahmad M, Garcia-Pinilla JM, Pantazis A, Dominguez F, John Baksi A, O'Regan DP, Rosen SD, Prasad SK, Lara-Pezzi E, Provencio M, Lyon AR, Alonso-Pulpon L, Cook SA, DePalma SR, Barton PJR, Aplenc R, Seidman JG, Ky B, Ware JS, Seidman CEet al., 2019, Genetic variants associated with cancer therapy-induced cardiomyopathy, Circulation, Vol: 140, Pages: 31-41, ISSN: 0009-7322

BackgroundCancer therapy-induced cardiomyopathy (CCM) is associated with cumulative drug exposures and pre-existing cardiovascular disorders. These parametersincompletely account for substantial inter-individual susceptibility to CCM. We hypothesized that rare variants in cardiomyopathy genes contribute to CCM.MethodsWe studied 213 CCM patients from three cohorts: retrospectively recruited adults with diverse cancers (n=99), prospectively phenotyped breast cancer adults (n=73) and prospectively phenotyped children with acute myeloid leukemia (n=41). Cardiomyopathy genes, including nine pre-specified genes were sequenced. The prevalence of rare variants was compared between CCM cohorts and The Cancer Genome Atlas (TCGA) participants(n=2053), healthy volunteers(n=445), and ancestry-matchedreference population. Clinical characteristics and outcomes were assessed, stratified by genotypes. A prevalent CCM genotype was modeled in anthracycline-treated mice.ResultsCCM was diagnosed 0.4-9 years after chemotherapy; 90% of these patients received anthracyclines. Adult CCM patients had cardiovascular risk factors similar to the U.S. population. Among nine prioritized genes CCM patients had more rare protein-altering variants than comparative cohorts (p≤1.98e-04). Titin-truncating variants (TTNtv) predominated, occurring in 7.5% CCM patients versus 1.1% TCGA participants (p=7.36e-08), 0.7% healthy volunteers (p=3.42e-06), and 0.6% reference population (p=5.87e-14). Adult CCM patients with TTNtv experienced more heart failure and atrial fibrillation (p=0.003)and impaired myocardial recovery (p=0.03) than those without.Consistent with human data, anthracycline-treated TTNtv mice and isolated TTNtv cardiomyocytes showed sustained contractile dysfunction unlike wildtype (p=0.0004 and p<0.002, respectively).ConclusionsUnrecognized rare variants in cardiomyopathy-associated genes, particularly TTNtv, increased the risk for CCM in children and adults, and adverse cardiac events

Journal article

Corden B, Jarman J, Whiffin N, Tayal U, Buchan R, Sehmi J, Harper A, Midwinter W, Lascelles K, Mason M, Baksi J, Pantazis A, Pennell D, Barton P, Prasad S, Wong T, Cook S, Ware Jet al., 2019, Association between titin truncating variants and life-threatening cardiac arrhythmias in patients with dilated cardiomyopathy and implantable defibrillator, JAMA Network Open, Vol: 2, Pages: 1-12, ISSN: 2574-3805

Importance There is a need for better arrhythmic risk stratification in nonischemic dilated cardiomyopathy (DCM). Titin-truncating variants (TTNtvs) in the TTN gene are the most common genetic cause of DCM and may be associated with higher risk of arrhythmias in patients with DCM.Objective To determine if TTNtv status is associated with the development of life-threatening ventricular arrhythmia and new persistent atrial fibrillation in patients with DCM and implanted cardioverter defibrillator (ICD) or cardiac resynchronization therapy defibrillator (CRT-D) devices.Design, Setting, and Participants This retrospective, multicenter cohort study recruited 148 patients with or without TTNtvs who had nonischemic DCM and ICD or CRT-D devices from secondary and tertiary cardiology clinics in the United Kingdom from February 1, 2011, to June 30, 2016, with a median (interquartile range) follow-up of 4.2 (2.1-6.5) years. Exclusion criteria were ischemic cardiomyopathy, primary valve disease, congenital heart disease, or a known or likely pathogenic variant in the lamin A/C gene. Analyses were performed February 1, 2017, to May 31, 2017.Main Outcome and Measures The primary outcome was time to first device-treated ventricular tachycardia of more than 200 beats/min or first device-treated ventricular fibrillation. Secondary outcome measures included time to first development of persistent atrial fibrillation.Results Of 148 patients recruited, 117 adult patients with nonischemic DCM and an ICD or CRT-D device (mean [SD] age, 56.9 [12.5] years; 76 [65.0%] men; 106 patients [90.6%] with primary prevention indications) were included. Having a TTNtv was associated with a higher risk of receiving appropriate ICD therapy (shock or antitachycardia pacing) for ventricular tachycardia or fibrillation (hazard ratio [HR], 4.9; 95% CI, 2.2-10.7; P < .001). This association was independent of all covariates, including midwall fibrosis measured by late gadolinium enhanc

Journal article

van Heesch S, Witte F, Schneider-Lunitz V, Schulz JF, Adami E, Faber AB, Kirchner M, Maatz H, Blachut S, Sandmann C-L, Kanda M, Worth CL, Schafer S, Calviello L, Merriott R, Patone G, Hummel O, Wyler E, Obermayer B, Mücke MB, Lindberg EL, Trnka F, Memczak S, Schilling M, Felkin LE, Barton PJR, Quaife NM, Vanezis K, Diecke S, Mukai M, Mah N, Oh S-J, Kurtz A, Schramm C, Schwinge D, Sebode M, Harakalova M, Asselbergs FW, Vink A, de Weger RA, Viswanathan S, Widjaja AA, Gärtner-Rommel A, Milting H, dos Remedios C, Knosalla C, Mertins P, Landthaler M, Vingron M, Linke WA, Seidman JG, Seidman CE, Rajewsky N, Ohler U, Cook SA, Hubner Net al., 2019, The translational landscape of the human heart, Cell, Vol: 178, Pages: 242-260.e29, ISSN: 0092-8674

Gene expression in human tissue has primarily been studied on the transcriptional level, largely neglecting translational regulation. Here, we analyze the translatomes of 80 human hearts to identify new translation events and quantify the effect of translational regulation. We show extensive translational control of cardiac gene expression, which is orchestrated in a process-specific manner. Translation downstream of predicted disease-causing protein-truncating variants appears to be frequent, suggesting inefficient translation termination. We identify hundreds of previously undetected microproteins, expressed from lncRNAs and circRNAs, for which we validate the protein products in vivo. The translation of microproteins is not restricted to the heart and prominent in the translatomes of human kidney and liver. We associate these microproteins with diverse cellular processes and compartments and find that many locate to the mitochondria. Importantly, dozens of microproteins are translated from lncRNAs with well-characterized noncoding functions, indicating previously unrecognized biology.

Journal article

Aguib Y, Allouba M, Afify A, Halawa S, ElKhateb M, Sous M, Galal A, Abdelrahman E, Shehata N, Sawy AE, Maghawry M, Anwer S, Kamel O, El-Mozy W, Khedr H, Essam A, Thabet N, Theotokis P, Buchan R, Govind R, Whiffin N, Walsh R, Aguib H, Elguindy A, Cook S, Barton P, Ware J, Yacoub Met al., 2019, Genomics of Egyptian healthy volunteers: the EHVol study, Publisher: bioRxiv

ABSTRACT Comprehensive genomic databases offer unprecedented opportunities towards effective tailored strategies for the prevention and treatment of disease. The integration of genomic and phenotypic data from diverse ethnic populations is also key to advancements in precision medicine and novel diagnostic technologies. Current reference genomic databases, however, are not representative of the global human population, making variant interpretation challenging and uncertain, especially in underrepresented populations such as the North African population. To address this, a study of 391 Egyptian healthy volunteers (EHVols) was initiated as a milestone towards establishing the 1000 Egyptian Genomes project.

Working paper

Walsh R, Mazzarotto F, Whiffin N, Buchan R, Midwinter W, Wilk A, Li N, Felkin L, Ingold N, Govind R, Ahmad M, Mazaika E, Allouba M, Zhang X, de Marvao A, Day SM, Ashley E, Colan SD, Michels M, Pereira AC, Jacoby D, Ho CY, Thomson KL, Watkins H, Barton PJR, Olivotto I, Cook SA, Ware JSet al., 2019, Quantitative approaches to variant classification increase the yield and precision of genetic testing in Mendelian diseases: The case of hypertrophic cardiomyopathy, Genome Medicine, Vol: 11, ISSN: 1756-994X

BackgroundInternational guidelines for variant interpretation in Mendelian disease set stringent criteria to report a variant as (likely) pathogenic, prioritising control of false-positive rate over test sensitivity and diagnostic yield. Genetic testing is also more likely informative in individuals with well-characterised variants from extensively studied European-ancestry populations. Inherited cardiomyopathies are relatively common Mendelian diseases that allow empirical calibration and assessment of this framework.MethodsWe compared rare variants in large hypertrophic cardiomyopathy (HCM) cohorts (up to 6179 cases) to reference populations to identify variant classes with high prior likelihoods of pathogenicity, as defined by etiological fraction (EF). We analysed the distribution of variants using a bespoke unsupervised clustering algorithm to identify gene regions in which variants are significantly clustered in cases.ResultsAnalysis of variant distribution identified regions in which variants are significantly enriched in cases and variant location was a better discriminator of pathogenicity than generic computational functional prediction algorithms. Non-truncating variant classes with an EF ≥ 0.95 were identified in five established HCM genes. Applying this approach leads to an estimated 14–20% increase in cases with actionable HCM variants, i.e. variants classified as pathogenic/likely pathogenic that might be used for predictive testing in probands’ relatives.ConclusionsWhen found in a patient confirmed to have disease, novel variants in some genes and regions are empirically shown to have a sufficiently high probability of pathogenicity to support a “likely pathogenic” classification, even without additional segregation or functional data. This could increase the yield of high confidence actionable variants, consistent with the framework and recommendations of current guidelines. The techniques outlined offer a consisten

Journal article

Whiffin N, Roberts AM, Minikel E, Zappala Z, Walsh R, O'Donnell-Luria AH, Karczewski KJ, Harrison SM, Thomson KL, Sage H, Ing AY, Barton PJR, Funke B, Cook SA, MacArthur DG, Ware JSet al., 2019, Using high-resolution variant frequencies empowers clinical genome interpretation and enables investigation of genetic architecture, American Journal of Human Genetics, Vol: 104, Pages: 187-190, ISSN: 0002-9297

Journal article

Horvat C, Johnson R, Lam L, Munro J, Mazzarotto F, Roberts A, Herman D, Parfenov M, Haghighli A, Macdonough B, DePalma S, Keogh A, Macdonald P, Hayward C, Roberts A, Barton PJR, Felkin L, Giannoulatou E, Cook S, Seidman J, Siedman C, Fatkin Det al., 2019, A gene-centric strategy for identifying disease-causing rare variants in dilated cardiomyopathy, Genetics in Medicine, Vol: 21, Pages: 133-143, ISSN: 1098-3600

PurposeWe evaluated strategies for identifying disease-causing variants in genetic testing for dilated cardiomyopathy (DCM).MethodsCardiomyopathy gene panel testing was performed in 532 DCM patients and 527 healthy control subjects. Rare variants in 41 genes were stratified using variant-level and gene-level characteristics.ResultsA majority of DCM cases and controls carried rare protein-altering cardiomyopathy gene variants. Variant-level characteristics alone had limited discriminative value. Differentiation between groups was substantially improved by addition of gene-level information that incorporated ranking of genes based on literature evidence for disease association. The odds of DCM were increased to nearly 9-fold for truncating variants or high-impact missense variants in the subset of 14 genes that had the strongest biological links to DCM (P <0.0001). For some of these genes, DCM-associated variants appeared to be clustered in key protein functional domains. Multiple rare variants were present in many family probands, however, there was generally only one “driver” pathogenic variant that cosegregated with disease.ConclusionRare variants in cardiomyopathy genes can be effectively stratified by combining variant-level and gene-level information. Prioritization of genes based on their a priori likelihood of disease causation is a key factor in identifying clinically actionable variants in cardiac genetic testing.

Journal article

Domínguez F, Cuenca S, Bilińska Z, Toro R, Villard E, Barriales-Villa R, Ochoa JP, Asselbergs F, Sammani A, Franaszczyk M, Akhtar M, Coronado-Albi MJ, Rangel-Sousa D, Rodriguez-Palomares JF, Jiménez-Jáimez J, Garcia-Pinilla JM, Ripoll-Vera T, Mogollon MV, Fontalba A, Garcia-Medina D, Doza JP, de Gonzalo-Calvo D, Cicerchia M, Salazar-Mendiguchia J, Pankuweit S, Morris Hey T, Mogensen J, Barton PJ, Charron P, Elliott P, Garcia-Pavia Pet al., 2018, Dilated cardiomyopathy due to BLC2-associated athanogene 3 (BAG3) mutations, Journal of the American College of Cardiology, Vol: 72, Pages: 2471-2481, ISSN: 0735-1097

BackgroundThe BAG3 (BLC2-associated athanogene 3) gene codes for an antiapoptotic protein located on the sarcomere Z-disc. Mutations in BAG3 are associated with dilated cardiomyopathy (DCM), but only a small number of cases have been reported to date, and the natural history of BAG3 cardiomyopathy is poorly understood.ObjectivesThis study sought to describe the phenotype and prognosis of BAG3 mutations in a large multicenter DCM cohort.MethodsThe study cohort comprised 129 individuals with a BAG3 mutation (62% males, 35.1 ± 15.0 years of age) followed at 18 European centers. Localization of BAG3 in cardiac tissue was analyzed in patients with truncating BAG3 mutations using immunohistochemistry.ResultsAt first evaluation, 57.4% of patients had DCM. After a median follow-up of 38 months (interquartile range: 7 to 95 months), 68.4% of patients had DCM and 26.1% who were initially phenotype-negative developed DCM. Disease penetrance in individuals >40 years of age was 80% at last evaluation, and there was a trend towards an earlier onset of DCM in men (age 34.6 ± 13.2 years vs. 40.7 ± 12.2 years; p = 0.053). The incidence of adverse cardiac events (death, left ventricular assist device, heart transplantation, and sustained ventricular arrhythmia) was 5.1% per year among individuals with DCM. Male sex, decreased left ventricular ejection fraction. and increased left ventricular end-diastolic diameter were associated with adverse cardiac events. Myocardial tissue from patients with a BAG3 mutation showed myofibril disarray and a relocation of BAG3 protein in the sarcomeric Z-disc.ConclusionsDCM caused by mutations in BAG3 is characterized by high penetrance in carriers >40 years of age and a high risk of progressive heart failure. Male sex, decreased left ventricular ejection fraction, and enlarged left ventricular end-diastolic diameter are associated with adverse outcomes in patients with BAG3 mutations.

Journal article

Chothani S, Schafer S, Adami E, Viswanathan S, Widjaja A, Langley S, Tan J, Pua CJ, DAgostino G, van Heesch S, Witte F, Felkin L, Christodoulou E, Dong J, Blachut S, Patone G, Barton PJR, Hubner N, Cook S, Rackham OJLet al., 2018, Translational control of cardiac fibrosis

<h4>Background</h4> Fibrosis is a common pathology in many cardiac disorders and is driven by the activation of resident fibroblasts. The global post-transcriptional mechanisms underlying fibroblast-to-myofibroblast conversion in the heart have not been explored. <h4>Methods</h4> Genome-wide changes of RNA transcription and translation during human cardiac fibroblast activation were monitored with RNA sequencing and ribosome profiling. We then used miRNA-and RNA-binding protein-based analyses to identify translational regulators of fibrogenic genes. To reveal post-transcriptional mechanisms in the human fibrotic heart, we then integrated our findings with cardiac ribosome occupancy levels of 30 dilated cardiomyopathy patients. <h4>Results</h4> We generated nucleotide-resolution translatome data during the TGFβ1-driven cellular transition of human cardiac fibroblasts to myofibroblasts. This identified dynamic changes of RNA transcription and translation at several time points during the fibrotic response, revealing transient and early-responder genes. Remarkably, about one-third of all changes in gene expression in activated fibroblasts are subject to translational regulation and dynamic variation in ribosome occupancy affects protein abundance independent of RNA levels. Targets of RNA-binding proteins were strongly enriched in post-transcriptionally regulated genes, suggesting genes such as MBNL2 can act as translational activators or repressors. Ribosome occupancy in the hearts of patients with dilated cardiomyopathy suggested an extensive post-transcriptional regulatory network underlying cardiac fibrosis. Key network hubs include RNA-binding proteins such as PUM2 and QKI that work in concert to regulate the translation of target transcripts in human diseased hearts. <h4>Conclusions</h4> We reveal widespread translational effects of TGFβ1 and define novel post-transcriptional events that control the fibrobl

Working paper

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