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Cardiomyopathy (CMP) is a heritable disorder. Over 50% of cases are gene-elusive on clinical gene panel testing. The contribution of variants in non-coding DNA elements that result in cryptic splicing and regulate gene expression has not been explored. We analyzed whole-genome sequencing (WGS) data in a discovery cohort of 209 pediatric CMP patients and 1953 independent replication genomes and exomes. We searched for protein-coding variants, and non-coding variants predicted to affect the function or expression of genes. Thirty-nine percent of cases harbored pathogenic coding variants in known CMP genes, and 5% harbored high-risk loss-of-function (LoF) variants in additional candidate CMP genes. Fifteen percent harbored high-risk regulatory variants in promoters and enhancers of CMP genes (odds ratio 2.25, p = 6.70 × 10−7 versus controls). Genes involved in α-dystroglycan glycosylation (FKTN, DTNA) and desmosomal signaling (DSC2, DSG2) were most highly enriched for regulatory variants (odds ratio 6.7–58.1). Functional effects were confirmed in patient myocardium and reporter assays in human cardiomyocytes, and in zebrafish CRISPR knockouts. We provide strong evidence for the genomic contribution of functionally active variants in new genes and in regulatory elements of known CMP genes to early onset CMP. This project was supported by the Ted Rogers Centre for Heart Research (SM, JE), the Canadian Institutes of Health Research (PJT 175034) (SM, JE) and by the Canadian Institutes of Health Research (ENP 161429), under the frame of ERA PerMed (SM). SM holds the Heart and Stroke Foundation of Canada & Robert M Freedom Chair in Cardiovascular Science. SWS holds the GlaxoSmithKline Endowed Chair in Genome Sciences at the Hospital for Sick Children and the University of Toronto. PGM holds a Canada Research Chair Tier 2 in Non-coding Disease Mechanisms. PGM acknowledges the support of the Government of Canada’s New Frontiers in Research Fund (NFRF), [NFRFE-2018-01305]. EO holds the Bitove Family Professorship of Adult Congenital Heart Disease. MM holds a Ramon y Cajal grant from the Spanish Ministry of Science and Innovation (RYC-2017-22249). WO is supported by funding from Fundació La Marató (321/C/2019). JB is funded by a Frans Van de Werf fellowship for clinical cardiovascular research, and by a senior clinical investigator fellowship of the FWO Flanders. KM was a National Science Foundation Graduate Research Fellow under grant no. DGE1144152 during the majority of the project. CS is the recipient of a National Health and Medical Research Council (NHMRC) Practitioner Fellowship (1154992). JI is the recipient of an NHMRC Career Development Fellowship (1162929). RDB is the recipient of a New South Wales Health Cardiovascular Disease Senior Scientist Grant. PSD is supported by the DBT/Wellcome Trust- Indian Alliance. We acknowledge the Labatt Family Heart Centre Biobank at the Hospital for Sick Children for access to DNA samples, and The Centre for Applied Genomics at the Hospital for Sick Children for performing WGS. We thank Xiucheng Cui and Emanuela Pannia for performing the zebrafish experiments at the SickKids Zebrafish Genetics and Disease Models Core (CRISPR-Cas9 and gRNA syntheses, zebrafish embryo microinjections, gRNA PCR validation, qRT-PCR, cardiac imaging). This research was made possible through access to the data and findings generated by the 100,000 Genomes Project. The 100,000 Genomes Project is managed by Genomics England Limited (a wholly owned company of the Department of Health and Social Care). The 100,000 Genomes Project is funded by the National Institute for Health Research and NHS England. The Wellcome Trust, Cancer Research UK and the Medical Research Council have also funded research infrastructure. The 100,000 Genomes Project uses data provided by patients and collected by the National Health Service as part of their care and support. We thank members of the ICGC/PCAWG working groups for generating the variant calls used in our case-control burden analyses. Peer Reviewed "Article signat per 38 autors/es: Robert Lesurf, Abdelrahman Said, Oyediran Akinrinade, Jeroen Breckpot, Kathleen Delfosse, Ting Liu, Roderick Yao, Gabrielle Persad, Fintan McKenna, Ramil R. Noche, Winona Oliveros, Kaia Mattioli, Shreya Shah, Anastasia Miron, Qian Yang, Guoliang Meng, Michelle Chan Seng Yue, Wilson W. L. Sung, Bhooma Thiruvahindrapuram, Jane Lougheed, Erwin Oechslin, Tapas Mondal, Lynn Bergin, John Smythe, Shashank Jayappa, Vinay J. Rao, Jayaprakash Shenthar, Perundurai S. Dhandapany, Christopher Semsarian, Robert G. Weintraub, Richard D. Bagnall, Jodie Ingles, Genomics England Research Consortium, Marta Melé, Philipp G. Maass, James Ellis, Stephen W. Scherer & Seema Mital"

Although many long non-coding RNAs (lncRNAs) exhibit lineage-specific expression, the vast majority remain functionally uncharacterized in the context of development. Here, we report the first described human embryonic stem cell (hESC) lines to repress (CRISPRi) or activate (CRISPRa) transcription during differentiation into all three germ layers, facilitating the modulation of lncRNA expression during early development. We performed an unbiased, genome-wide CRISPRi screen targeting thousands of lncRNA loci expressed during endoderm differentiation. While dozens of lncRNA loci were required for proper differentiation, most differentially expressed lncRNAs were not, supporting the necessity for functional screening instead of relying solely on gene expression analyses. In parallel, we developed a clustering approach to infer mechanisms of action of lncRNA hits based on a variety of genomic features. We subsequently identified and validated FOXD3-AS1 as a functional lncRNA essential for pluripotency and differentiation. Taken together, the cell lines and methodology described herein can be adapted to discover and characterize novel regulators of differentiation into any lineage.

This work was funded by the US National Institutes of Health (NIH) grant P01GM099117, and by the National Science Foundation Graduate Research Fellowship under the grant DGE1144152 (J.R.H. and K.M.). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript., Although many long non-coding RNAs (lncRNAs) exhibit lineage-specific expression, the vast majority remain functionally uncharacterized in the context of development. Here, we report the first described human embryonic stem cell (hESC) lines to repress (CRISPRi) or activate (CRISPRa) transcription during differentiation into all three germ layers, facilitating the modulation of lncRNA expression during early development. We performed an unbiased, genome-wide CRISPRi screen targeting thousands of lncRNA loci expressed during endoderm differentiation. While dozens of lncRNA loci were required for proper differentiation, most differentially expressed lncRNAs were not, supporting the necessity for functional screening instead of relying solely on gene expression analyses. In parallel, we developed a clustering approach to infer mechanisms of action of lncRNA hits based on a variety of genomic features. We subsequently identified and validated FOXD3-AS1 as a functional lncRNA essential for pluripotency and differentiation. Taken together, the cell lines and methodology described herein can be adapted to discover and characterize novel regulators of differentiation into any lineage., United States Department of Health & Human Services National Institutes of Health (NIH) - USA P01GM099117, National Science Foundation (NSF) DGE1144152

Although many long non-coding RNAs (lncRNAs) exhibit lineage-specific expression, the vast majority remain functionally uncharacterized in the context of development. Here, we report the first described human embryonic stem cell (hESC) lines to repress (CRISPRi) or activate (CRISPRa) transcription during differentiation into all three germ layers, facilitating the modulation of lncRNA expression during early development. We performed an unbiased, genome-wide CRISPRi screen targeting thousands of lncRNA loci expressed during endoderm differentiation. While dozens of lncRNA loci were required for proper differentiation, most differentially expressed lncRNAs were not, supporting the necessity for functional screening instead of relying solely on gene expression analyses. In parallel, we developed a clustering approach to infer mechanisms of action of lncRNA hits based on a variety of genomic features. We subsequently identified and validated FOXD3-AS1 as a functional lncRNA essential for pluripotency and differentiation. Taken together, the cell lines and methodology described herein can be adapted to discover and characterize novel regulators of differentiation into any lineage.

Cardiomyopathy (CMP) is a heritable genetic disorder. Protein-coding variants account for 20-30% of cases. The contribution of variants in non-coding DNA elements that regulate gene expression has not been explored. We performed whole-genome sequencing (WGS) of 228 unrelated CMP families. Besides pathogenic protein-coding variants in known CMP genes, 5% cases harbored rare loss-of-function variants in novel cardiac genes, with NRAP and FHOD3 being strong candidates. WGS also revealed a high burden of high-risk variants in promoters and enhancers of CMP genes in an additional 20% cases (Odds ratio 2.14, 95% CI 1.60-2.86, p=5.26×10−7 vs 1326 controls) with genes involved in α-dystroglycan glycosylation (FKTN, DTNA) and desmosomal signaling (DSC2, DSG2) specifically enriched for regulatory variants (False discovery rate

Background Gene expression differences between species are driven by both cis and trans effects. Whereas cis effects are caused by genetic variants located on the same DNA molecule as the target gene, trans effects are due to genetic variants that affect diffusible elements. Previous studies have mostly assessed the impact of cis and trans effects at the gene level. However, how cis and trans effects differentially impact regulatory elements such as enhancers and promoters remains poorly understood. Here, we use massively parallel reporter assays to directly measure the transcriptional outputs of thousands of individual regulatory elements in embryonic stem cells and measure cis and trans effects between human and mouse. Results Our approach reveals that cis effects are widespread across transcribed regulatory elements, and the strongest cis effects are associated with the disruption of motifs recognized by strong transcriptional activators. Conversely, we find that trans effects are rare but stronger in enhancers than promoters and are associated with a subset of transcription factors that are differentially expressed between human and mouse. While we find that cis-trans compensation is common within promoters, we do not see evidence of widespread cis-trans compensation at enhancers. Cis-trans compensation is inversely correlated with enhancer redundancy, suggesting that such compensation may often occur across multiple enhancers. Conclusions Our results highlight differences in the mode of evolution between promoters and enhancers in complex mammalian genomes and indicate that studying the evolution of individual regulatory elements is pivotal to understand the tempo and mode of gene expression evolution.

Gene expression differences between species are driven by bothcisandtranseffects. Whereasciseffects are caused by genetic variants in close proximity to the target gene,transeffects are due to distal genetic variants that affect diffusible elements such as transcription factors. Previous studies have mostly assessed the impact ofcisandtranseffects at the gene level. However, howcisandtranseffects differentially impact regulatory elements such as enhancers and promoters remains poorly understood. Here, we used massively parallel reporter assays to directly measurecisandtranseffects between human and mouse embryonic stem cells at thousands of individual regulatory elements. Our approach revealed thatciseffects are widespread across regulatory elements, and the strongestciseffects are associated with the disruption of motifs recognized by strong transcriptional activators. Conversely, we found thattranseffects are rare but stronger in enhancers than promoters, and can be attributed to a subset of transcription factors that are differentially expressed between human and mouse. While previous studies have found extensive co-occurrence ofcisandtranseffects in opposite directions that stabilize gene expression throughout evolution, we find thatcis-transcompensation is uncommon within individual regulatory elements. Thus, our results are consistent with a model wherein compensatorycis-transeffects at the gene level are explained bycisandtranseffects that separately impact several regulatory elements rather thancis-transeffects that occur simultaneously within a single regulatory element. Together, these results indicate that studying the evolution of individual regulatory elements is pivotal to understand the tempo and mode of gene expression evolution.