scholarly journals Epigenetics and the exposomes: Obesity and beyond

2013 ◽  
Vol 06 (03) ◽  
pp. 089-093
Author(s):  
Rita P. Raman ◽  
Anita D. Raman
Keyword(s):  
Environmental Factors ◽  
Association Studies ◽  
Adult Life ◽  
Genetic Alterations ◽  
Common Disease ◽  
Neural Function ◽  
Genome Wide Association Studies ◽  
Negative Effects ◽  
Environmental Signals ◽  
And Function

ABSTRACTThe specific genetic alterations that result in diseases and complex syndromes have been and continue to be identified. Search for the origins of disease have led to investigations into the roles of dietary and environmental factors as potential triggers or modifiers of risk. Genome-wide association studies have identified concepts such as the rare variant-common disease hypothesis and the common variant-common disease hypothesis.1 Through association studies, unique gene-environment interactions, which may occur with or without specific periods of permissiveness or vulnerabilities, have also been identified. Major conditions where the role of exposomes and epigenetics are rapidly evolving are obesity, neurological disorders, immune disorders and cancers. These concepts are particularly intriguing in the context of obesity. BACKGROUND: Epigenetics can be defined as heritable traits resulting from changes in DNA or chromatin structure without alterations in the DNA sequence.2 Nutritional epigenetics is seen as a means for the prevention of developmental diseases and cancer, and to delay processes associated with aging.3,4 Diseases in which epigenetic factors are considered significant include type 2 diabetes mellitus, obesity, inflammation, cardiovascular diseases, neurocognitive disorders, and immune diseases, with neural function influenced by environmental factors including early experience.5 Studies with rodent models suggest that during both early development and in adult life, environmental signals can activate intracellular pathways that directly remodel the epigenome, leading to changes in gene expression and function. These studies define a biological basis for the interplay between environmental signals and the genome in the regulation of individual differences in behavior, cognition, and physiology.6 In reproduction, certain genes are turned on while others are turned off in the process of imprinting. In the case of imprinting, even though there are two copies of the gene, only one copy is expressed and there is no substitute functional allele. For this reason, imprinting makes the imprinted genes more vulnerable to the negative effects of mutations.7

scholarly journals Host Genetics and Gut Microbiome: Perspectives for Multiple Sclerosis

Genes ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 1181
Author(s):  
Alessandro Maglione ◽  
Miriam Zuccalà ◽  
Martina Tosi ◽  
Marinella Clerico ◽  
Simona Rolla
Keyword(s):  
Multiple Sclerosis ◽  
Environmental Factors ◽  
Lupus Erythematosus ◽  
Gut Microbiome ◽  
Complex Disease ◽  
Current Knowledge ◽  
Association Studies ◽  
Future Research ◽  
Genome Wide Association Studies ◽  
Host Genetics

As a complex disease, Multiple Sclerosis (MS)’s etiology is determined by both genetic and environmental factors. In the last decade, the gut microbiome has emerged as an important environmental factor, but its interaction with host genetics is still unknown. In this review, we focus on these dual aspects of MS pathogenesis: we describe the current knowledge on genetic factors related to MS, based on genome-wide association studies, and then illustrate the interactions between the immune system, gut microbiome and central nervous system in MS, summarizing the evidence available from Experimental Autoimmune Encephalomyelitis mouse models and studies in patients. Finally, as the understanding of influence of host genetics on the gut microbiome composition in MS is in its infancy, we explore this issue based on the evidence currently available from other autoimmune diseases that share with MS the interplay of genetic with environmental factors (Inflammatory Bowel Disease, Rheumatoid Arthritis and Systemic Lupus Erythematosus), and discuss avenues for future research.

scholarly journals Pesticide Exposures Induce Male-Mediated Reproductive Toxicity: A Review

2017 ◽  
Vol 9 (13) ◽  
pp. 122
Author(s):  
Nur Afizah Yusoff ◽  
Siti Balkis Budin ◽  
Izatus Shima Taib
Keyword(s):  
Environmental Factors ◽  
Germ Line ◽  
Sperm Quality ◽  
Reproductive Toxicity ◽  
Adult Life ◽  
Negative Effects ◽  
Male Germ Line ◽  
Hormonal Function ◽  
Pesticide Exposures ◽  
Genetic And Environmental Factors

Infertility remains a continuing globally problem wherever couples worldwide were infertile as much as 42 million in 1990 and keep projecting to 48.5 million in 2010. Male-mediated infertility becomes one of the numerous concerns due to pesticide especially sperm quality as revealed with raising number of animal and human studies in latter-day among researchers. Pesticides have been used since the early days as pest control in agriculture, as vector controls in malaria and dengue as well as subject to much regulation. The reproductive system might be affected with some negative effects from pesticides that lead to interference with the male hormonal function. Polyunsaturated fatty acid (PUFA) content in the sperm cell membrane makes it become highly susceptible towards reactive oxygen species (ROS), thus leading to sperm damage. Besides known genetic and environmental factors, research during the last two decades has highlight on several mechanisms and their association with male infertility. The male germ line undergoes extensive epigenetic modifications throughout fetal to adult life hence vulnerable to environmental factors that may influence fertility. The present literature will help in understanding the mechanisms of pesticide in inducing male-mediated reproductive toxicity.

scholarly journals Genetic Variants in SNCA and the Risk of Sporadic Parkinson’s Disease and Clinical Outcomes: A Review

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Clarissa Loureiro das Chagas Campêlo ◽  
Regina Helena Silva
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Environmental Factors ◽  
Clinical Outcomes ◽  
Association Studies ◽  
Clinical Aspects ◽  
Genome Wide Association Studies ◽  
Snca Gene ◽  
Increased Risk

There is increasing evidence of the contribution of genetic susceptibility to the etiology of Parkinson’s disease (PD). Genetic variations in the SNCA gene are well established by linkage and genome-wide association studies. Positive associations of single nucleotide polymorphisms (SNPs) in SNCA and increased risk for PD were found. However, the role of SNCA variants in individual traits or phenotypes of PD is unknown. Here, we reviewed the current literature and identified 57 studies, performed in fourteen different countries, that investigated SNCA variants and susceptibility to PD. We discussed the findings based on environmental factors, history of PD, clinical outcomes, and ethnicity. In conclusion, SNPs within the SNCA gene can modify the susceptibility to PD, leading to increased or decreased risk. The risk associations of some SNPs varied among samples. Of notice, no studies in South American or African populations were found. There is little information about the effects of these variants on particular clinical aspects of PD, such as motor and nonmotor symptoms. Similarly, evidence of possible interactions between SNCA SNPs and environmental factors or disease progression is scarce. There is a need to expand the clinical applicability of these data as well as to investigate the role of SNCA SNPs in populations with different ethnic backgrounds.

scholarly journals Leveraging mouse chromatin data for heritability enrichment informs common disease architecture and reveals cortical layer contributions to schizophrenia

2018 ◽  
Author(s):  
Paul W. Hook ◽  
Andrew S. McCallion
Keyword(s):  
Association Studies ◽  
Cortical Layer ◽  
Genome Wide Association ◽  
Cell Populations ◽  
Common Disease ◽  
Open Chromatin ◽  
Genome Wide Association Studies ◽  
Genome Wide ◽  
Excitatory Neurons ◽  
Cellular Context

Genome-wide association studies have implicated thousands of non-coding variants across human phenotypes. However, they cannot directly inform the cellular context in which disease-associated variants act. Here, we use open chromatin profiles from discrete mouse cell populations to address this challenge. We applied stratified linkage disequilibrium score regression and evaluated heritability enrichment in 64 genome-wide association studies, emphasizing schizophrenia. We provide evidence that mouse-derived human open chromatin profiles can serve as powerful proxies for difficult to obtain human cell populations, facilitating the illumination of common disease heritability enrichment across an array of human phenotypes. We demonstrate signatures from discrete subpopulations of cortical excitatory and inhibitory neurons are significantly enriched for schizophrenia heritability with maximal enrichment in discrete cortical layer V excitatory neurons. We also show differences between schizophrenia and bipolar disorder are concentrated in excitatory neurons in layers II-III, IV, V as well as the dentate gyrus. Finally, we use these data to fine-map variants in 177 schizophrenia loci, nominating variants in 104/177 loci, and place them in the cellular context where they may modulate risk.

scholarly journals Understanding PITX2-dependent Atrial Fibrillation Mechanisms through Computational Models

2021 ◽  
Author(s):  
Jieyun Bai ◽  
Yaosheng Lu ◽  
Yijie Zhu ◽  
Huijin Wang ◽  
Dechun Yin ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Computational Models ◽  
Association Studies ◽  
Basic Research ◽  
Genome Wide Association Studies ◽  
Gene Coding ◽  
Patient Health ◽  
Quantitative Understanding ◽  
Whole Heart ◽  
And Function

Atrial fibrillation (AF) is a common arrhythmia. Better prevention and treatment of AF are needed to reduce AF-associated morbidity and mortality. Several major mechanisms cause AF in patients, including a genetic predisposition to develop AF. Genome-wide association studies have identified genetic variants associated with AF populations, with the strongest hits clustering on chromosome 4q25, close to the gene coding for the homeobox transcription PITX2. Because of the inherent complexity of the human heart, experimental and basic research on PITX2-dependent AF is not sufficient for understanding atrial functional proprieties. Linking PITX2 to ion channels, cells, tissues, atria and the whole heart, computational models are necessary for achieving a quantitative understanding of atrial structure and function in PITX2-dependent AF. Computational approaches are used to capture all that we know about PITX2-dependent AF and to develop improved therapies. In the present review, we discuss advances in atrial modelling and focus on the mechanistic links between PITX2 and AF. Challenges in applying models for improving patient health are described, as well as a summary of future perspectives.

scholarly journals THE EFFECT OF SINGLE NUCLEOTIDE POLYMORPHISM (SNP) IN GLIOBLASTOMA MULTIFORME

2021 ◽  
Author(s):  
Asmita Ghosh ◽  
Dattatreya Mukherjee ◽  
Parth Patel ◽  
Debraj Mukhopadhyay
Keyword(s):  
Single Nucleotide Polymorphism ◽  
Glioblastoma Multiforme ◽  
Association Studies ◽  
Disease Onset ◽  
Genetic Alterations ◽  
Genome Wide Association Studies ◽  
Nucleotide Polymorphisms ◽  
Coding Region ◽  
Nucleotide Polymorphism ◽  
Single Nucleotide

Single nucleotide polymorphism is a genetic substitution of a base pair at a single position of the genome. SNPs are a common phenomenon and influence mRNA expression. Half of the SNPs occur in the non-coding region with 25% being mis-sense mutation and 25% being silent mutations. SNPs belong to the last generation of molecular markers which is identified through SNP mapping. SNPs are extensively studied to distinguish genetic expression and protein synthesis. These genetic differences are a major source of diseases in humans like cancers. One of the most common types of cancer of the brain is the Glioblastoma Multiforme that accounts for more than 80% of the malignant primary brain tumors (PBT). Researchers have found out a potential role of various SNPs in the genome to have a strong relation with Glioma formation and proliferation. Most SNPs are either not discovered, or their biological mechanisms are unknown, making it difficult to link putative associations with disease onset. The given review aims to identify some of the most common SNPs associated with GBM and classify the genetic basis along with future prospects. These SNPs are pioneer in Genome Wide Association studies to help in cancer research and identification of specific genetic alterations liked to GBM. Single Nucleotide Polymorphisms in a gene can be used as genetic biomarkers to aid better understanding of the mechanism of cancer formation, its aetiology, progression and metastatic behaviour.

scholarly journals Exome sequencing and genotyping identify a rare variant in NLRP7 gene associated with ulcerative colitis

2017 ◽  
Author(s):  
Alexandros Onoufriadis ◽  
Kristina Stone ◽  
Antreas Katsiamides ◽  
Ariella Amar ◽  
Yasmin Omar ◽  
...  
Keyword(s):  
Ulcerative Colitis ◽  
Exome Sequencing ◽  
Genetic Variants ◽  
Odds Ratio ◽  
High Throughput Sequencing ◽  
Association Studies ◽  
Common Disease ◽  
Genome Wide Association Studies ◽  
Increased Risk ◽  
Coding Variants

AbstractBackground and aimsAlthough genome-wide association studies (GWAS) in inflammatory bowel disease (IBD) have identified a large number of common disease susceptibility alleles for both Crohn’s disease (CD) and ulcerative colitis (UC), a substantial fraction of IBD heritability remains unexplained, suggesting that rare coding genetic variants may also have a role in pathogenesis. We used high-throughput sequencing in families with multiple cases of IBD, followed by genotyping of cases and controls, to investigate whether rare protein altering genetic variants are associated with susceptibility to IBD.MethodsWhole exome sequencing was carried out in 10 families in which 3 or more individuals were affected with IBD. A stepwise filtering approach was applied to exome variants to identify potential causal variants. Follow-up genotyping was performed in 6,025 IBD cases (2,948 CD; 3,077 UC) and 7,238 controls.ResultsOur exome variant analysis revealed coding variants in the NLRP7 gene that were present in affected individuals in two distinct families. Genotyping of the two variants, p.S361L and p.R801H, in IBD cases and controls showed that the p.S361L variant was significantly associated with an increased risk of ulcerative colitis (odds ratio 4.79, p=0.0039) and IBD (odds ratio 3.17, p=0.037). A combined analysis of both variants showed suggestive association with an increased risk of IBD (odds ratio 2.77, p=0.018).ConclusionsThe results suggest that NLRP7 signalling and inflammasome formation may be a significant component in the pathogenesis of IBD.

scholarly journals Combining SNP-to-gene linking strategies to pinpoint disease genes and assess disease omnigenicity

2021 ◽  
Author(s):  
Steven Gazal ◽  
Omer Weissbrod ◽  
Farhad Hormozdiari ◽  
Kushal Dey ◽  
Joseph Nasser ◽  
...  
Keyword(s):  
Fine Mapping ◽  
Complex Traits ◽  
Target Genes ◽  
Disease Risk ◽  
Association Studies ◽  
Common Disease ◽  
Disease Genes ◽  
Genome Wide Association Studies ◽  
Functional Interpretation ◽  
Genome Wide

Although genome-wide association studies (GWAS) have identified thousands of disease-associated common SNPs, these SNPs generally do not implicate the underlying target genes, as most disease SNPs are regulatory. Many SNP-to-gene (S2G) linking strategies have been developed to link regulatory SNPs to the genes that they regulate in cis, but it is unclear how these strategies should be applied in the context of interpreting common disease risk variants. We developed a framework for evaluating and combining different S2G strategies to optimize their informativeness for common disease risk, leveraging polygenic analyses of disease heritability to define and estimate their precision and recall. We applied our framework to GWAS summary statistics for 63 diseases and complex traits (average N=314K), evaluating 50 S2G strategies. Our optimal combined S2G strategy (cS2G) included 7 constituent S2G strategies (Exon, Promoter, 2 fine-mapped cis-eQTL strategies, EpiMap enhancer-gene linking, Activity-By-Contact (ABC), and Cicero), and achieved a precision of 0.75 and a recall of 0.33, more than doubling the precision and/or recall of any individual strategy; this implies that 33% of SNP-heritability can be linked to causal genes with 75% confidence. We applied cS2G to fine-mapping results for 49 UK Biobank diseases/traits to predict 7,111 causal SNP-gene-disease triplets (with S2G-derived functional interpretation) with high confidence. Finally, we applied cS2G to genome-wide fine-mapping results for these traits (not restricted to GWAS loci) to rank genes by the heritability linked to each gene, providing an empirical assessment of disease omnigenicity; averaging across traits, we determined that the top 200 (1%) of ranked genes explained roughly half of the heritability linked to all genes. Our results highlight the benefits of our cS2G strategy in providing functional interpretation of GWAS findings; we anticipate that precision and recall will increase further under our framework as improved functional assays lead to improved S2G strategies. 

scholarly journals Candidate Genes for Age at Menarche Are Associated With Uterine Leiomyoma

2021 ◽  
Vol 11 ◽  
Author(s):  
Irina Ponomarenko ◽  
Evgeny Reshetnikov ◽  
Alexey Polonikov ◽  
Irina Verzilina ◽  
Inna Sorokina ◽  
...  
Keyword(s):  
Candidate Genes ◽  
Uterine Leiomyoma ◽  
Association Studies ◽  
Pubertal Development ◽  
Reproductive Organs ◽  
Age At Menarche ◽  
Genome Wide Association Studies ◽  
Induced Abortions ◽  
Trait Locus ◽  
And Function

Age at menarche (AAM) is an important marker of the pubertal development and function of the hypothalamic–pituitary–ovarian system. It was reported as a possible factor for a risk of uterine leiomyoma (UL). However, while more than 350 loci for AAM have been determined by genome-wide association studies (GWASs) to date, no studies of these loci for their association with UL have been conducted so far. In this study, we analyzed 52 candidate loci for AAM for possible association with UL in a sample of 569 patients and 981 controls. The results of the study suggested that 23 out of the 52 studied polymorphisms had association with UL. Locus rs7759938 LIN28B was individually associated with the disease according to the dominant model. Twenty loci were associated with UL within 11 most significant models of intergenic interactions. Nine loci involved in 16 most significant models of interactions between single-nucleotide polymorphism (SNP), induced abortions, and chronic endometritis were associated with UL. Among the 23 loci associated with UL, 16 manifested association also with either AAM (7 SNPs) or height and/or body mass index (BMI) (13 SNPs). The above 23 SNPs and 514 SNPs linked to them have non-synonymous, regulatory, and expression quantitative trait locus (eQTL) significance for 35 genes, which play roles in the pathways related to development of the female reproductive organs and hormone-mediated signaling [false discovery rate (FDR) ≤ 0.05]. This is the first study reporting associations of candidate genes for AAM with UL.

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