Induced pluripotent stem cells (iPSCs) are an established cellular system to study the impact of genetic variants in derived cell types and developmental contexts. However, in their pluripotent ...state, the disease impact of genetic variants is less well known. Here, we integrate data from 1,367 human iPSC lines to comprehensively map common and rare regulatory variants in human pluripotent cells. Using this population-scale resource, we report hundreds of new colocalization events for human traits specific to iPSCs, and find increased power to identify rare regulatory variants compared with somatic tissues. Finally, we demonstrate how iPSCs enable the identification of causal genes for rare diseases.
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GEOZS, IJS, IMTLJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK, ZAGLJ
The ClinGen Inborn Errors of Metabolism Working Group was tasked with creating a comprehensive, standardized knowledge base of genes and variants for metabolic diseases. Phenylalanine hydroxylase ...(PAH) deficiency was chosen to pilot development of the Working Group's standards and guidelines. A PAH variant curation expert panel (VCEP) was created to facilitate this process. Following ACMG‐AMP variant interpretation guidelines, we present the development of these standards in the context of PAH variant curation and interpretation. Existing ACMG‐AMP rules were adjusted based on disease (6) or strength (5) or both (2). Disease adjustments include allele frequency thresholds, functional assay thresholds, and phenotype‐specific guidelines. Our validation of PAH‐specific variant interpretation guidelines is presented using 85 variants. The PAH VCEP interpretations were concordant with existing interpretations in ClinVar for 69 variants (81%). Development of biocurator tools and standards are also described. Using the PAH‐specific ACMG‐AMP guidelines, 714 PAH variants have been curated and will be submitted to ClinVar. We also discuss strategies and challenges in applying ACMG‐AMP guidelines to autosomal recessive metabolic disease, and the curation of variants in these genes.
The ClinGen Inborn Errors of Metabolism Working Group chose phenylalanine hydroxylase (PAH) deficiency to pilot metabolic‐specific ACMG‐AMP variant interpretation guidelines. A PAH variant curation expert panel adjusted existing ACMG‐AMP rules based on disease (6) or strength (5) or both (2). Disease adjustments include allele frequency thresholds, functional assay thresholds, and phenotype‐specific guidelines. Our validation of PAH‐specific variant interpretation guidelines are presented. Using these guidelines 714 PAH variants have been curated and will be submitted to ClinVar.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Biallelic variants in IL6ST, encoding GP130, cause a recessive form of hyper-IgE syndrome (HIES) characterized by high IgE level, eosinophilia, defective acute phase response, susceptibility to ...bacterial infections, and skeletal abnormalities due to cytokine-selective loss of function in GP130, with defective IL-6 and IL-11 and variable oncostatin M (OSM) and IL-27 levels but sparing leukemia inhibitory factor (LIF) signaling.
Our aim was to understand the functional and structural impact of recessive HIES-associated IL6ST variants.
We investigated a patient with HIES by using exome, genome, and RNA sequencing. Functional assays assessed IL-6, IL-11, IL-27, OSM, LIF, CT-1, CLC, and CNTF signaling. Molecular dynamics simulations and structural modeling of GP130 cytokine receptor complexes were performed.
We identified a patient with compound heterozygous novel missense variants in IL6ST (p.Ala517Pro and the exon-skipping null variant p.Gly484_Pro518delinsArg). The p.Ala517Pro variant resulted in a more profound IL-6– and IL-11–dominated signaling defect than did the previously identified recessive HIES IL6ST variants p.Asn404Tyr and p.Pro498Leu. Molecular dynamics simulations suggested that the p.Ala517Pro and p.Asn404Tyr variants result in increased flexibility of the extracellular membrane–proximal domains of GP130. We propose a structural model that explains the cytokine selectivity of pathogenic IL6ST variants that result in recessive HIES. The variants destabilized the conformation of the hexameric cytokine receptor complexes, whereas the trimeric LIF-GP130-LIFR complex remained stable through an additional membrane-proximal interaction. Deletion of this membrane-proximal interaction site in GP130 consequently caused additional defective LIF signaling and Stüve-Wiedemann syndrome.
Our data provide a structural basis to understand clinical phenotypes in patients with IL6ST variants.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
KCTD7 is a member of the potassium channel tetramerization domain-containing protein family and has been associated with progressive myoclonic epilepsy (PME), characterized by myoclonus, epilepsy, ...and neurological deterioration. Here we report four affected individuals from two unrelated families in which we identified KCTD7 compound heterozygous single nucleotide variants through exome sequencing. RNAseq was used to detect a non-annotated splicing junction created by a synonymous variant in the second family. Whole-cell patch-clamp analysis of neuroblastoma cells overexpressing the patients' variant alleles demonstrated aberrant potassium regulation. While all four patients experienced many of the common clinical features of PME, they also showed variable phenotypes not previously reported, including dysautonomia, brain pathology findings including a significantly reduced thalamus, and the lack of myoclonic seizures. To gain further insight into the pathogenesis of the disorder, zinc finger nucleases were used to generate kctd7 knockout zebrafish. Kctd7 homozygous mutants showed global dysregulation of gene expression and increased transcription of c-fos, which has previously been correlated with seizure activity in animal models. Together these findings expand the known phenotypic spectrum of KCTD7-associated PME, report a new animal model for future studies, and contribute valuable insights into the disease.
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DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Identification of clinically significant genetic alterations involved in human disease has been dramatically accelerated by developments in next-generation sequencing technologies. However, the ...infrastructure and accessible comprehensive curation tools necessary for analyzing an individual patient genome and interpreting genetic variants to inform healthcare management have been lacking.
Here we present the ClinGen Variant Curation Interface (VCI), a global open-source variant classification platform for supporting the application of evidence criteria and classification of variants based on the ACMG/AMP variant classification guidelines. The VCI is among a suite of tools developed by the NIH-funded Clinical Genome Resource (ClinGen) Consortium and supports an FDA-recognized human variant curation process. Essential to this is the ability to enable collaboration and peer review across ClinGen Expert Panels supporting users in comprehensively identifying, annotating, and sharing relevant evidence while making variant pathogenicity assertions. To facilitate evidence-based improvements in human variant classification, the VCI is publicly available to the genomics community. Navigation workflows support users providing guidance to comprehensively apply the ACMG/AMP evidence criteria and document provenance for asserting variant classifications.
The VCI offers a central platform for clinical variant classification that fills a gap in the learning healthcare system, facilitates widespread adoption of standards for clinical curation, and is available at https://curation.clinicalgenome.org.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
COVID-19 has quickly spread throughout the world, necessitating assessment of effective containment methods. The purpose of this study was to examine the impact of government mandated school ...closures, stay at home orders and mask requirements
Cumulative incidence rates were calculated at 14-day intervals until the day of the first vaccine administration in the country. Rate ratios were calculated using negative binomial regression while investigating the effects of adjusting for several sociodemographic and medical factors
Faster implementation of mask mandates was consistently shown to be protective. States with mask mandates made at three to six months had a 1.61 times higher rate than those who implemented within one month (adjusted rate ratio = 1.61, 95% confidence interval: 1.23-2.10, P = .001). States with mask mandates made after 6 months or with no mandate had a 2.16 times higher rate than those who implemented within 1 month (adjusted rate ratio = 2.16, 95% confidence interval: 1.64-2.88, P < .0001). In contrast, both stay at home orders and school closures had no significant influence on disease trajectory.
The benefits of mask mandates are apparent, especially when mandates were issued within a month. The impact of school closing and stay at home orders were less clear.
Our results suggest that of the different physical distancing measures implemented by the government, mask mandates are the most important.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Here we describe a patient who presented with a history of congenital diaphragmatic hernia, inguinal hernia, and recurrent umbilical hernia. She also has joint laxity, hypotonia, and dysmorphic ...features. A unifying diagnosis was not identified based on her clinical phenotype. As part of her evaluation through the Undiagnosed Diseases Network, trio whole-exome sequencing was performed. Pathogenic variants in
and
were identified as causing two distinct autosomal dominant conditions, each with de novo inheritance. Fibrillin 1 (
mutations are associated with Marfan syndrome and a spectrum of similar phenotypes.
mutations are associated with trichorhinophalangeal syndrome types I and III. Features of both conditions are evident in the patient reported here. Discrepant features of the conditions (e.g., stature) and the young age of the patient may have made a clinical diagnosis more difficult in the absence of exome-wide genetic testing.
Decreased sequencing costs have led to an explosion of genetic and genomic data. These data have revealed thousands of candidate human disease variants. Establishing which variants cause phenotypes ...and diseases, however, has remained challenging. Significant progress has been made, including advances by the National Institutes of Health (NIH)-funded Undiagnosed Diseases Network (UDN). However, 6000-13,000 additional disease genes remain to be identified. The continued discovery of rare diseases and their genetic underpinnings provides benefits to affected patients, of whom there are more than 400 million worldwide, and also advances understanding the mechanisms of more common diseases. Platforms employing model organisms enable discovery of novel gene-disease relationships, help establish variant pathogenicity, and often lead to the exploration of underlying mechanisms of pathophysiology that suggest new therapies. The Model Organism Screening Center (MOSC) of the UDN is a unique resource dedicated to utilizing informatics and functional studies in model organisms, including worm (Caenorhabditis elegans), fly (Drosophila melanogaster), and zebrafish (Danio rerio), to aid in diagnosis. The MOSC has directly contributed to the diagnosis of challenging cases, including multiple patients with complex, multi-organ phenotypes. In addition, the MOSC provides a framework for how basic scientists and clinicians can collaborate to drive diagnoses. Customized experimental plans take into account patient presentations, specific genes and variant(s), and appropriateness of each model organism for analysis. The MOSC also generates bioinformatic and experimental tools and reagents for the wider scientific community. Two elements of the MOSC that have been instrumental in its success are (1) multidisciplinary teams with expertise in variant bioinformatics and in human and model organism genetics, and (2) mechanisms for ongoing communication with clinical teams. Here we provide a position statement regarding the central role of model organisms for continued discovery of disease genes, and we advocate for the continuation and expansion of MOSC-type research entities as a Model Organisms Network (MON) to be funded through grant applications submitted to the NIH, family groups focused on specific rare diseases, other philanthropic organizations, industry partnerships, and other sources of support.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
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