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Schizophrenia Bulletin Sep 2022Schizophrenia has been robustly associated with multiple genetic and environmental risk factors. Childhood adversity is one of the most widely replicated environmental... (Meta-Analysis)
Meta-Analysis
BACKGROUND AND HYPOTHESIS
Schizophrenia has been robustly associated with multiple genetic and environmental risk factors. Childhood adversity is one of the most widely replicated environmental risk factors for schizophrenia, but it is unclear if schizophrenia genetic risk alleles contribute to this association.
STUDY DESIGN
In this systematic review and meta-analysis, we assessed the evidence for gene-environment correlation (genes influence likelihood of environmental exposure) between schizophrenia polygenic risk score (PRS) and reported childhood adversity. We also assessed the evidence for a gene-environment interaction (genes influence sensitivity to environmental exposure) in relation to the outcome of schizophrenia and/or psychosis. This study was registered on PROSPERO (CRD42020182812). Following PRISMA guidelines, a search for relevant literature was conducted using Cochrane, MEDLINE, PsycINFO, Web of Science, and Scopus databases until February 2022. All studies that examined the association between schizophrenia PRS and childhood adversity were included.
STUDY RESULTS
Seventeen of 650 identified studies met the inclusion criteria and were assessed against the Newcastle-Ottawa Scale for quality. The meta-analysis found evidence for gene-environment correlation between schizophrenia PRS and childhood adversity (r = .02; 95% CI = 0.01, 0.03; P = .001), but the effect was small and therefore likely to explain only a small proportion of the association between childhood adversity and psychosis. The 4 studies that investigated a gene-environment interaction between schizophrenia PRS and childhood adversity in increasing risk of psychosis reported inconsistent results.
CONCLUSIONS
These findings suggest that a gene-environment correlation could explain a small proportion of the relationship between reported childhood adversity and psychosis.
Topics: Adverse Childhood Experiences; Child; Gene-Environment Interaction; Humans; Multifactorial Inheritance; Risk; Schizophrenia
PubMed: 35674151
DOI: 10.1093/schbul/sbac049 -
International Journal of Molecular... Mar 2020Recent studies have led to considerable advances in the identification of genetic variants associated with type 1 and type 2 diabetes. An approach for converting genetic...
Recent studies have led to considerable advances in the identification of genetic variants associated with type 1 and type 2 diabetes. An approach for converting genetic data into a predictive measure of disease susceptibility is to add the risk effects of loci into a polygenic risk score. In order to summarize the recent findings, we conducted a systematic review of studies comparing the accuracy of polygenic risk scores developed during the last two decades. We selected 15 risk scores from three databases (Scopus, Web of Science and PubMed) enrolled in this systematic review. We identified three polygenic risk scores that discriminate between type 1 diabetes patients and healthy people, one that discriminate between type 1 and type 2 diabetes, two that discriminate between type 1 and monogenic diabetes and nine polygenic risk scores that discriminate between type 2 diabetes patients and healthy people. Prediction accuracy of polygenic risk scores was assessed by comparing the area under the curve. The actual benefits, potential obstacles and possible solutions for the implementation of polygenic risk scores in clinical practice were also discussed. Develop strategies to establish the clinical validity of polygenic risk scores by creating a framework for the interpretation of findings and their translation into actual evidence, are the way to demonstrate their utility in medical practice.
Topics: Diabetes Mellitus, Type 1; Diabetes Mellitus, Type 2; Genetic Predisposition to Disease; Humans; Multifactorial Inheritance
PubMed: 32131491
DOI: 10.3390/ijms21051703 -
Behavior Genetics Jul 2019Studies testing the effect of single genetic variants on substance use have had modest success. This paper reviewed 39 studies using polygenic measures to test...
Studies testing the effect of single genetic variants on substance use have had modest success. This paper reviewed 39 studies using polygenic measures to test interaction with any type of environmental exposure (G×E) in alcohol, tobacco, and cannabis use. Studies using haplotype combinations, sum scores of candidate-gene risk alleles, and polygenic scores (PS) were included. Overall study quality was moderate, with lower ratings for the polygenic methods in the haplotype and candidate-gene score studies. Heterogeneity in investigated environmental exposures, genetic factors, and outcomes was substantial. Most studies (N = 30) reported at least one significant G×E interaction, but overall evidence was weak. The majority (N = 26) found results in line with differential susceptibility and diathesis-stress frameworks. Future studies should pay more attention to methodological and statistical rigor, and focus on replication efforts. Additional work is needed before firm conclusions can be drawn about the importance of G×E in the etiology of substance use.
Topics: Alcohol Drinking; Alleles; Cannabis; Ethanol; Gene Frequency; Gene-Environment Interaction; Genetic Predisposition to Disease; Haplotypes; Humans; Marijuana Use; Multifactorial Inheritance; Risk Factors; Nicotiana; Tobacco Use
PubMed: 31111357
DOI: 10.1007/s10519-019-09958-7 -
Genetics in Medicine : Official Journal... Jun 2022Recently, preimplantation genetic testing (PGT) for polygenic conditions (PGT-P) has been introduced commercially. In view of the lack of specific guidance on this... (Review)
Review
PURPOSE
Recently, preimplantation genetic testing (PGT) for polygenic conditions (PGT-P) has been introduced commercially. In view of the lack of specific guidance on this development, we analyzed normative documents on PGT for monogenic conditions (PGT-M) to understand what we can learn from these documents for recommendations for PGT-P.
METHODS
We conducted a systematic review of normative guidelines and recommendations on PGT-M. The aim was to understand what the current consensus and disagreements are on ethical acceptability of PGT-M and how this compares with PGT-P.
RESULTS
We analyzed 38 documents by advisory committees at the national, European, and global level. In total, 2 themes were identified, which included the following: (1) what PGT is considered appropriate for and (2) who can make decisions regarding the use of PGT. Many aspects of PGT-M documents apply to PGT-P as well. Additional factors such as the fact that PGT-P screens for risk indications of multiple polygenic conditions increase ethical difficulties regarding severity, risk, autonomy, and informed decision-making.
CONCLUSION
On the basis of PGT-M normative documents, we conclude that ethical acceptability for PGT-P is limited. Our findings present various factors that have to be considered for the development of guidelines and the appropriateness of PGT.
Topics: Aneuploidy; Female; Genetic Testing; Humans; Morals; Multifactorial Inheritance; Pregnancy; Preimplantation Diagnosis
PubMed: 35341652
DOI: 10.1016/j.gim.2022.03.001 -
Molecular Psychiatry Mar 2022Schizophrenia is a severe, complex mental disorder characterized by a combination of positive symptoms, negative symptoms, and impaired cognitive function. Schizophrenia...
Schizophrenia is a severe, complex mental disorder characterized by a combination of positive symptoms, negative symptoms, and impaired cognitive function. Schizophrenia is highly heritable (~80%) with multifactorial etiology and complex polygenic genetic architecture. Despite the large number of genetic variants associated with schizophrenia, few causal variants have been established. Gaining insight into the mechanistic influences of these genetic variants may facilitate our ability to apply these findings to prevention and treatment. Though there have been more than 300 studies of gene expression in schizophrenia over the past 15 years, none of the studies have yielded consistent evidence for specific genes that contribute to schizophrenia risk. The aim of this work is to conduct a systematic review and synthesis of case-control studies of genome-wide gene expression in schizophrenia. Comprehensive literature searches were completed in PubMed, EmBase, and Web of Science, and after a systematic review of the studies, data were extracted from those that met the following inclusion criteria: human case-control studies comparing the genome-wide transcriptome of individuals diagnosed with schizophrenia to healthy controls published between January 1, 2000 and June 30, 2020 in the English language. Genes differentially expressed in cases were extracted from these studies, and overlapping genes were compared to previous research findings from the genome-wide association, structural variation, and tissue-expression studies. The transcriptome-wide analysis identified different genes than those previously reported in genome-wide association, exome sequencing, and structural variation studies of schizophrenia. Only one gene, GBP2, was replicated in five studies. Previous work has shown that this gene may play a role in immune function in the etiology of schizophrenia, which in turn could have implications for risk profiling, prevention, and treatment. This review highlights the methodological inconsistencies that impede valid meta-analyses and synthesis across studies. Standardization of the use of covariates, gene nomenclature, and methods for reporting results could enhance our understanding of the potential mechanisms through which genes exert their influence on the etiology of schizophrenia. Although these results are promising, collaborative efforts with harmonization of methodology will facilitate the identification of the role of genes underlying schizophrenia.
Topics: Case-Control Studies; Genetic Predisposition to Disease; Genome-Wide Association Study; Humans; Multifactorial Inheritance; Schizophrenia; Exome Sequencing
PubMed: 35091668
DOI: 10.1038/s41380-021-01420-7 -
NeuroImage. Clinical 2020Diffusion magnetic resonance imaging (dMRI) is an imaging technique which probes the random motion of water molecules in tissues and has been widely applied to... (Review)
Review
Diffusion magnetic resonance imaging (dMRI) is an imaging technique which probes the random motion of water molecules in tissues and has been widely applied to investigate changes in white matter microstructure in Alzheimer's Disease. This paper aims to systematically review studies that examined the effect of Alzheimer's risk genes on white matter microstructure. We assimilated findings from 37 studies and reviewed their diffusion pre-processing and analysis methods. Most studies estimate the diffusion tensor (DT) and compare derived quantitative measures such as fractional anisotropy and mean diffusivity between groups. Those with increased AD genetic risk are associated with reduced anisotropy and increased diffusivity across the brain, most notably the temporal and frontal lobes, cingulum and corpus callosum. Structural abnormalities are most evident amongst those with established Alzheimer's Disease. Recent studies employ signal representations and analysis frameworks beyond DT MRI but show that dMRI overall lacks specificity to disease pathology. However, as the field advances, these techniques may prove useful in pre-symptomatic diagnosis or staging of Alzheimer's disease.
Topics: Alzheimer Disease; Anisotropy; Brain; Diffusion Magnetic Resonance Imaging; Diffusion Tensor Imaging; Humans; White Matter
PubMed: 32758801
DOI: 10.1016/j.nicl.2020.102359 -
Genetics in Medicine : Official Journal... Sep 2022Single-nucleotide variations (SNVs) (formerly single-nucleotide polymorphism [SNV]) influence genetic predisposition to endometrial cancer. We hypothesized that a...
PURPOSE
Single-nucleotide variations (SNVs) (formerly single-nucleotide polymorphism [SNV]) influence genetic predisposition to endometrial cancer. We hypothesized that a polygenic risk score (PRS) comprising multiple SNVs may improve endometrial cancer risk prediction for targeted screening and prevention.
METHODS
We developed PRSs from SNVs identified from a systematic review of published studies and suggestive SNVs from the Endometrial Cancer Association Consortium. These were tested in an independent study of 555 surgically-confirmed endometrial cancer cases and 1202 geographically-matched controls from Manchester, United Kingdom and validated in 1676 cases and 116,960 controls from the UK Biobank (UKBB).
RESULTS
Age and body mass index predicted endometrial cancer in both data sets (Manchester: area under the receiver operator curve [AUC] = 0.77, 95% CI = 0.74-0.80; UKBB: AUC = 0.74, 95% CI = 0.73-0.75). The AUC for PRS19, PRS24, and PRS72 were 0.58, 0.55, and 0.57 in the Manchester study and 0.56, 0.54, and 0.54 in UKBB, respectively. For PRS19, women in the third tertile had a 2.1-fold increased risk of endometrial cancer compared with those in the first tertile of the Manchester study (odds ratio = 2.08, 95% CI = 1.61-2.68, P = 5.75E-9). Combining PRS19 with age and body mass index improved discriminatory power (Manchester study: AUC = 0.79, 95% CI = 0.76-0.82; UKBB: AUC =0.75, 95% CI = 0.73-0.76).
CONCLUSION
An endometrial cancer risk prediction model incorporating a PRS derived from multiple SNVs may help stratify women for screening and prevention strategies.
Topics: Female; Humans; Endometrial Neoplasms; Genetic Predisposition to Disease; Genome-Wide Association Study; Multifactorial Inheritance; Polymorphism, Single Nucleotide; Risk Assessment; Risk Factors
PubMed: 35704044
DOI: 10.1016/j.gim.2022.05.014 -
Journal of Alzheimer's Disease : JAD 2020Late-onset Alzheimer's disease (AD) is highly heritable. The effect of many common genetic variants, single nucleotide polymorphisms (SNPs), confer risk. Variants are...
BACKGROUND
Late-onset Alzheimer's disease (AD) is highly heritable. The effect of many common genetic variants, single nucleotide polymorphisms (SNPs), confer risk. Variants are clustered in areas of biology, notably immunity and inflammation, cholesterol metabolism, endocytosis, and ubiquitination. Polygenic scores (PRS), which weight the sum of an individual's risk alleles, have been used to draw inferences about the pathological processes underpinning AD.
OBJECTIVE
This paper aims to systematically review how AD PRS are being used to study a range of outcomes and phenotypes related to neurodegeneration.
METHODS
We searched the literature from July 2008-July 2018 following PRISMA guidelines.
RESULTS
57 studies met criteria. The AD PRS can distinguish AD cases from controls. The ability of AD PRS to predict conversion from mild cognitive impairment (MCI) to AD was less clear. There was strong evidence of association between AD PRS and cognitive impairment. AD PRS were correlated with a number of biological phenotypes associated with AD pathology, such as neuroimaging changes and amyloid and tau measures. Pathway-specific polygenic scores were also associated with AD-related biologically relevant phenotypes.
CONCLUSION
PRS can predict AD effectively and are associated with cognitive impairment. There is also evidence of association between AD PRS and other phenotypes relevant to neurodegeneration. The associations between pathway specific polygenic scores and phenotypic changes may allow us to define the biology of the disease in individuals and indicate who may benefit from specific treatments. Longitudinal cohort studies are required to test the ability of PGS to delineate pathway-specific disease activity.
Topics: Alzheimer Disease; Genetic Predisposition to Disease; Genetic Testing; Humans; Multifactorial Inheritance; Precision Medicine
PubMed: 32250305
DOI: 10.3233/JAD-191233 -
Human Genetics Nov 2022Genomic medicine aims to improve health using the individual genomic data of people to inform care. While clinical utility of genomic medicine in many monogenic,... (Review)
Review
Genomic medicine aims to improve health using the individual genomic data of people to inform care. While clinical utility of genomic medicine in many monogenic, Mendelian disorders is amply demonstrated, clinical utility is less evident in polygenic traits, e.g., coronary artery disease or breast cancer. Polygenic risk scores (PRS) are subsets of individual genotypes designed to capture heritability of common traits, and hence to allow the stratification of risk of the trait in a population. We systematically reviewed the PubMed database for unequivocal evidence of clinical utility of polygenic risk scores, using stringent inclusion and exclusion criteria. While we identified studies demonstrating clinical validity in conditions where medical intervention based on a PRS is likely to benefit patient outcome, we did not identify a single study demonstrating unequivocally such a benefit, i.e. clinical utility. We conclude that while the routine use of PRSs hold great promise, translational research is still needed before they should enter mainstream clinical practice.
Topics: Genetic Predisposition to Disease; Genomic Medicine; Genomics; Humans; Multifactorial Inheritance; Risk Factors
PubMed: 35488921
DOI: 10.1007/s00439-022-02452-x -
Annals of Palliative Medicine Aug 2022Ischaemic stroke is a common neurological disease and a leading cause of severe disability and death in developed countries. In most cases, stroke is thought to be a... (Meta-Analysis)
Meta-Analysis
BACKGROUND
Ischaemic stroke is a common neurological disease and a leading cause of severe disability and death in developed countries. In most cases, stroke is thought to be a multifactorial disorder or complex trait for which classic patterns of inheritance cannot be shown. Xuesaitong is one of the most commonly used medicines for treating ischemic stroke in China. However, compared to the conventional therapy, the effectiveness and safety of Xuesaitong for ischemic stroke needs to be further systematically reviewed and determined.
METHODS
Relevant randomized controlled trials (RCTs) examining the use of the Xuesaitong soft capsule in the treatment of patients with ischemic stroke were identified from databases, including the China National Knowledge Infrastructure, Wanfang, PubMed, Embase, and Web of Science databases. Next, 2 researchers independently extracted information from the included studies, analyzed the data using STATA 15.0 software, and evaluated the quality of the included studies using RevMan 5.3.
RESULTS
A total of 17 RCTs (comprising 1,942 patients with ischemic stroke) were included in the meta-analysis. The meta-analysis results showed that the Xuesaitong soft capsule treatment increased patients' total effective rate compared to conventional or other drug treatments, and improved patients' Clinical Severity Score (CSS scores) or Barthel index (BI) score. A further subgroup analysis stratified by different treatment times showed that Xuesaitong soft capsule treatment at 4 and 8 weeks improved CSS scores more than treatment at 2 weeks in patients with ischemic stroke. Additionally, the Xuesaitong soft capsule also significantly improved plasma viscosity, whole-blood viscosity at high and low shear rates, fibrinogen, hematocrit, and the effect on traditional Chinese medicine (TCM) single symptoms or signs in patients with ischemic stroke.
DISCUSSION
In summary, compared to conventional or other drug treatments, the Xuesaitong soft capsule treatment was beneficial in improving patients' TCM symptoms (e.g., crooked mouth and tongue, and dizziness) and various indicators. Further, Xuesaitong soft capsule may be a safe and effective drug for the treatment of ischemic stroke. And large-scale randomized clinical trials are needed to further confirm our findings.
Topics: Capsules; Drugs, Chinese Herbal; Humans; Ischemic Stroke; Saponins; Stroke
PubMed: 36064360
DOI: 10.21037/apm-22-748