Missense variants in phospholamban and cardiac myosin binding protein identified in patients with a family history and clinical diagnosis of dilated cardiomyopathy.

As the genetic landscape of cardiomyopathies continues to expand, the identification of missense variants in disease-associated genes frequently leads to a classification of variant of uncertain significance (VUS). For the proper reclassification of such variants, functional characterization is an important contributor to the proper assessment of pathogenic potential. Several missense variants in the calcium transport regulatory protein phospholamban have been associated with dilated cardiomyopathy. However, >40 missense variants in this transmembrane peptide are currently known and most remain classified as VUS with little clinical information. Similarly, missense variants in cardiac myosin binding protein have been associated with hypertrophic cardiomyopathy. However, hundreds of variants are known and many have low penetrance and are often found in control populations. Herein, we focused on novel missense variants in phospholamban, an Ala15-Thr variant found in a 4-year-old female and a Pro21-Thr variant found in a 60-year-old female, both with a family history and clinical diagnosis of dilated cardiomyopathy. The patients also harbored a Val896-Met variant in cardiac myosin binding protein. The phospholamban variants caused defects in the function, phosphorylation, and dephosphorylation of this calcium transport regulatory peptide, and we classified these variants as potentially pathogenic. The variant in cardiac myosin binding protein alters the structure of the protein. While this variant has been classified as benign, it has the potential to be a low-risk susceptibility variant because of the structural change in cardiac myosin binding protein. Our studies provide new biochemical evidence for missense variants previously classified as benign or VUS.

Human Genetic Variation Influences Enteric Fever Progression.

In the 21st century, enteric fever is still causing a significant number of mortalities, especially in high-risk regions of the world. Genetic studies involving the genome and transcriptome have revealed a broad set of candidate genetic polymorphisms associated with susceptibility to and the severity of enteric fever. This review attempted to explain and discuss the past and the most recent findings on human genetic variants affecting the progression of Salmonella typhoidal species infection, particularly toll-like receptor (TLR) 4, TLR5, interleukin (IL-) 4, natural resistance-associated macrophage protein 1 (NRAMP1), VAC14, PARK2/PACRG, cystic fibrosis transmembrane conductance regulator (CFTR), major-histocompatibility-complex (MHC) class II and class III. These polymorphisms on disease susceptibility or progression in patients could be related to multiple mechanisms in eliminating both intracellular and extracellular Salmonella typhoidal species. Here, we also highlighted the limitations in the studies reported, which led to inconclusive results in association studies. Nevertheless, the knowledge obtained through this review may shed some light on the development of risk prediction tools, novel therapies as well as strategies towards developing a personalised typhoid vaccine.

COVID-19: aspectos relacionados a la susceptibilidad genética y defectos congénitos / COVID-19: Aspects of genetic susceptibility and congenital defects

RESUMEN Introducción: la COVID-19 (acrónimo del inglés c oronavirus disease 2019) es una enfermedad infecciosa de reciente descripción, causada por el SARS-CoV-2, sin tratamiento efectivo. La identificación de variantes genéticas que intervienen en la respuesta a la COVID-19; así como la posibilidad de trasmisión materno-fetal del SARS-CoV-2 no solo permitirán ampliar los conocimientos sobre su fisiopatología; sino además estratificar los grupos de la población, y según su riesgo, implementar medidas preventivas y tratamientos personalizados, incluida la prioridad en el uso de vacunas. Objetivo: describir aspectos relacionados con la susceptibilidad genética y defectos congénitos en la COVID-19. Material y Métodos: se realizó una investigación tipo revisión bibliográfica; para identificar los documentos que se revisarían se consultó la base bibliográfica PubMed/Medline, incluyendo los trabajos del 2019 y 2020. Se incluyó publicaciones recomendadas por expertos, preferiblemente publicados en los últimos 10 años; luego de una valoración cualitativa, se realizó una síntesis. Desarrollo: están descritas mutaciones de los genes: ACE2, ACE1, TMPRSS2, TLR7, así como haplotipos HLA asociadas a la susceptibilidad genética a la COVID-19. Variantes de los genes: SLC6A20, LZTFL1, CCR9, FYCO1, CXCR6 y XCR1; así como de los que codifican para el receptor de la Vitamina D y las citoquinas pro inflamatorias (como las IL-1, IL-6, IL-12, IFN-γ, y TNT-α), pudieran también estar relacionadas con un incremento de la susceptibilidad al SARS-CoV-2. Ante la posibilidad de trasmisión vertical de la COVID-19 y su posible papel teratogénico, las embarazadas constituyen un grupo de riesgo. Conclusión: variantes genéticas humanas son factores de susceptibilidad genética al virus SARS-CoV-2, que puede ser causa de defectos congénitos(AU)

ABSTRACT Introduction: COVID-19 (acronym for Coronavirus Disease 2019) is a recently described infectious disease caused by SARS-CoV-2, without effective treatment. Identification of genetic variants involved in the response to COVID-19 as well as the possibility of maternal-fetal transmission of SARS-CoV-2 will not only allow us to expand our knowledge of the pathophysiology of COVID-19, but also stratify population groups according to their risks in order to implement preventive measures and personalized treatments, including the priority in the use of vaccines. Objective: To describe aspects related to congenital defects and genetic susceptibility to the SARS-CoV-2 virus. Material and Methods: A bibliographic review was carried out. Medline and PubMed bibliographic databases were searched. Studies published between 2019 and 2020 were included as well the ones recommended by experts, preferably published within the last 10 years. After qualitative evaluation, synthesis was made. Development: Mutations in ACE2, ACE1, TMPRSS2, TLR7 genes, as well as HLA haplotypes associated with genetic susceptibility to COVID-19 are described. Variants in the genes SLC6A20, LZTFL1, CCR9, FYCO1, CXCR6, XCR1 and in those codifying vitamin D receptor and proinflammatory cytokines (IL-1, IL-6, IL-12, IFN-γ, and TNF-α) could be related to an increased susceptibility to SARS-CoV-2. Due to the risk of vertical transmission of COVID-19 and its possible teratogenic effect, pregnant women are included in the risk group. Conclusion: Human genetic variants are factors of genetic susceptibility to the SARS-CoV-2 virus which may cause congenital defects(AU)

eQTL Mapping Using Transcription Factor Affinity.

In the last decades, thousands of common genetic variants have been associated with human diseases by genome-wide association studies (GWAS). However, the functional interpretation of GWAS hits is usually nontrivial, especially because most of them lay outside the coding genome. These noncoding variants presumably exert their effect by altering gene expression levels; therefore, expression quantitative trait loci (eQTL) mapping analyses represent an important step in understanding their functional relevance and identifying the target genes. Here we describe an alternative strategy for the detection of eQTL that takes into account the combined effect of genetic variants within regulatory regions and leverages the idea that changes in gene expression often are the consequence of the alteration of transcription factor (TF) binding.

The Length of the Expressed 3' UTR Is an Intermediate Molecular Phenotype Linking Genetic Variants to Complex Diseases.

In the last decades, genome-wide association studies (GWAS) have uncovered tens of thousands of associations between common genetic variants and complex diseases. However, these statistical associations can rarely be interpreted functionally and mechanistically. As the majority of the disease-associated variants are located far from coding sequences, even the relevant gene is often unclear. A way to gain insight into the relevant mechanisms is to study the genetic determinants of intermediate molecular phenotypes, such as gene expression and transcript structure. We propose a computational strategy to discover genetic variants affecting the relative expression of alternative 3' untranslated region (UTR) isoforms, generated through alternative polyadenylation, a widespread posttranscriptional regulatory mechanism known to have relevant functional consequences. When applied to a large dataset in which whole genome and RNA sequencing data are available for 373 European individuals, 2,530 genes with alternative polyadenylation quantitative trait loci (apaQTL) were identified. We analyze and discuss possible mechanisms of action of these variants, and we show that they are significantly enriched in GWAS hits, in particular those concerning immune-related and neurological disorders. Our results point to an important role for genetically determined alternative polyadenylation in affecting predisposition to complex diseases, and suggest new ways to extract functional information from GWAS data.

Complementation of Yeast Genes with Human Genes as an Experimental Platform for Functional Testing of Human Genetic Variants.

While the pace of discovery of human genetic variants in tumors, patients, and diverse populations has rapidly accelerated, deciphering their functional consequence has become rate-limiting. Using cross-species complementation, model organisms like the budding yeast, Saccharomyces cerevisiae, can be utilized to fill this gap and serve as a platform for testing human genetic variants. To this end, we performed two parallel screens, a one-to-one complementation screen for essential yeast genes implicated in chromosome instability and a pool-to-pool screen that queried all possible essential yeast genes for rescue of lethality by all possible human homologs. Our work identified 65 human cDNAs that can replace the null allele of essential yeast genes, including the nonorthologous pair yRFT1/hSEC61A1. We chose four human cDNAs (hLIG1, hSSRP1, hPPP1CA, and hPPP1CC) for which their yeast gene counterparts function in chromosome stability and assayed in yeast 35 tumor-specific missense mutations for growth defects and sensitivity to DNA-damaging agents. This resulted in a set of human-yeast gene complementation pairs that allow human genetic variants to be readily characterized in yeast, and a prioritized list of somatic mutations that could contribute to chromosome instability in human tumors. These data establish the utility of this cross-species experimental approach.