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Dyslipidemia, inflammation, calcification, and adiposity in aortic stenosis: a genome-wide study.
Yu Chen, H, Dina, C, Small, AM, Shaffer, CM, Levinson, RT, Helgadóttir, A, Capoulade, R, Munter, HM, Martinsson, A, Cairns, BJ, et al
European heart journal. 2023;44(21):1927-1939
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Aortic stenosis (AS) is a form of heart disease that is an abnormal narrowing of the aortic valve in the heart, which restricts blood flow. Although being over the age of 75 appears to increase the risk for development, it is unclear as to who else may be at risk. A better understanding of genetic factors, which may be involved in its development could better help to identify those at risk. This meta-analysis of 10 cohort studies aimed to determine genetic contributors to AS and possible mechanisms involved. The results showed that 15 different gene variations were strongly associated with AS including those in the CELSR2-SORT1, NLRP6, LPA and SMC2 genes. Interestingly some of these genes were also identified in individuals with African and Latin American ancestry. It was concluded that these genes, many of which are associated with hardening of the arteries, altered lipid metabolism, excess storage of fat, and inflammation may all contribute to AS. This study could be used by healthcare professionals to understand that there are specific genetic contributors to the development of AS and that in the future we may be able to target these to identify high-risk individuals and use them in therapeutic management.
Abstract
AIMS: Although highly heritable, the genetic etiology of calcific aortic stenosis (AS) remains incompletely understood. The aim of this study was to discover novel genetic contributors to AS and to integrate functional, expression, and cross-phenotype data to identify mechanisms of AS. METHODS AND RESULTS A genome-wide meta-analysis of 11.6 million variants in 10 cohorts involving 653 867 European ancestry participants (13 765 cases) was performed. Seventeen loci were associated with AS at P ≤ 5 × 10-8, of which 15 replicated in an independent cohort of 90 828 participants (7111 cases), including CELSR2-SORT1, NLRP6, and SMC2. A genetic risk score comprised of the index variants was associated with AS [odds ratio (OR) per standard deviation, 1.31; 95% confidence interval (CI), 1.26-1.35; P = 2.7 × 10-51] and aortic valve calcium (OR per standard deviation, 1.22; 95% CI, 1.08-1.37; P = 1.4 × 10-3), after adjustment for known risk factors. A phenome-wide association study indicated multiple associations with coronary artery disease, apolipoprotein B, and triglycerides. Mendelian randomization supported a causal role for apolipoprotein B-containing lipoprotein particles in AS (OR per g/L of apolipoprotein B, 3.85; 95% CI, 2.90-5.12; P = 2.1 × 10-20) and replicated previous findings of causality for lipoprotein(a) (OR per natural logarithm, 1.20; 95% CI, 1.17-1.23; P = 4.8 × 10-73) and body mass index (OR per kg/m2, 1.07; 95% CI, 1.05-1.9; P = 1.9 × 10-12). Colocalization analyses using the GTEx database identified a role for differential expression of the genes LPA, SORT1, ACTR2, NOTCH4, IL6R, and FADS. CONCLUSION Dyslipidemia, inflammation, calcification, and adiposity play important roles in the etiology of AS, implicating novel treatments and prevention strategies.
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Genetic risk-factors for anxiety in healthy individuals: polymorphisms in genes important for the HPA axis.
Lindholm, H, Morrison, I, Krettek, A, Malm, D, Novembre, G, Handlin, L
BMC medical genetics. 2020;21(1):184
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Anxiety is a complex disorder that involves alterations in hormones secreted from glands in the brain. Genetic variations in these hormones can mean that some individuals are more susceptible to anxiety disorders. The aim of this observational study was to investigate possible relationships between genetic changes in brain hormones and anxiety in 72 individuals. The results showed that women were more likely than men to report feelings of anxiety and there were several relationships between genetic variations in brain hormones and self-reported measures of anxiety. It was concluded that genetic variations in brain hormones are associated with anxiety disorders in healthy individuals. This study could be used by healthcare professionals to understand how genetics could play a role in anxiety and that certain genes could be used to identify individuals at risk of anxiety disorders.
Abstract
BACKGROUND Two important aspects for the development of anxiety disorders are genetic predisposition and alterations in the hypothalamic-pituitary-adrenal (HPA) axis. In order to identify genetic risk-factors for anxiety, the aim of this exploratory study was to investigate possible relationships between genetic polymorphisms in genes important for the regulation and activity of the HPA axis and self-assessed anxiety in healthy individuals. METHODS DNA from 72 healthy participants, 37 women and 35 men, were included in the analyses. Their DNA was extracted and analysed for the following Single Nucleotide Polymorphisms (SNP)s: rs41423247 in the NR3C1 gene, rs1360780 in the FKBP5 gene, rs53576 in the OXTR gene, 5-HTTLPR in SLC6A4 gene and rs6295 in the HTR1A gene. Self-assessed anxiety was measured by the State and Trait Anxiety Inventory (STAI) questionnaire. RESULTS Self-assessed measure of both STAI-S and STAI-T were significantly higher in female than in male participants (p = 0.030 and p = 0.036, respectively). For SNP rs41423247 in the NR3C1 gene, there was a significant difference in females in the score for STAI-S, where carriers of the G allele had higher scores compared to the females that were homozygous for the C allele (p < 0.01). For the SNP rs53576 in the OXTR gene, there was a significant difference in males, where carriers of the A allele had higher scores in STAI-T compared to the males that were homozygous for the G allele (p < 0.01). CONCLUSION This study shows that SNP rs41423247 in the NR3C1 gene and SNP rs53576 in the OXTR gene are associated with self-assessed anxiety in healthy individuals in a gender-specific manner. This suggests that these SNP candidates are possible genetic risk-factors for anxiety.
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Genomics in Personalized Nutrition: Can You "Eat for Your Genes"?
Mullins, VA, Bresette, W, Johnstone, L, Hallmark, B, Chilton, FH
Nutrients. 2020;12(10)
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Genetics may have a huge influence on how nutrients are processed within the body, challenging the one-size-fits-all dietary approach and highlighting the possible need for personalised nutrition based on genetics. There are a growing number of companies that offer genetic nutritional testing, however the science behind this is still in its infancy. This review of 130 papers aimed to discuss the role of genetics in nutrition and the possibility for precision nutrition. The paper stated that dietary components, especially those found in the modern Western diet (WD), may detrimentally interact with genetics. Overconsumption of certain nutrients, changes in nutrient exposure throughout history and the ability of certain nutrients to make small genetic changes are all ways that genetics and diet can interact. Therefore, understanding how an individual’s genetics have been and continue to be affected by diet may ensure effective nutrition recommendations. Ethical implications should be considered prior to testing and whether results will motivate or dissuade an individual to make dietary changes assessed. It was concluded that personalised nutrition recommendations in the future will rely upon understanding an individual’s genetics, however current research has a limited understanding of the numerous diet-genetic interactions. This paper could be used by healthcare professionals to evaluate the need for genetic testing to make personalised recommendations.
Abstract
Genome-wide single nucleotide polymorphism (SNP) data are now quickly and inexpensively acquired, raising the prospect of creating personalized dietary recommendations based on an individual's genetic variability at multiple SNPs. However, relatively little is known about most specific gene-diet interactions, and many molecular and clinical phenotypes of interest (e.g., body mass index [BMI]) involve multiple genes. In this review, we discuss direct to consumer genetic testing (DTC-GT) and the current potential for precision nutrition based on an individual's genetic data. We review important issues such as dietary exposure and genetic architecture addressing the concepts of penetrance, pleiotropy, epistasis, polygenicity, and epigenetics. More specifically, we discuss how they complicate using genotypic data to predict phenotypes as well as response to dietary interventions. Then, several examples (including caffeine sensitivity, alcohol dependence, non-alcoholic fatty liver disease, obesity/appetite, cardiovascular, Alzheimer's disease, folate metabolism, long-chain fatty acid biosynthesis, and vitamin D metabolism) are provided illustrating how genotypic information could be used to inform nutritional recommendations. We conclude by examining ethical considerations and practical applications for using genetic information to inform dietary choices and the future role genetics may play in adopting changes beyond population-wide healthy eating guidelines.
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Functional variants in the sucrase-isomaltase gene associate with increased risk of irritable bowel syndrome.
Henström, M, Diekmann, L, Bonfiglio, F, Hadizadeh, F, Kuech, EM, von Köckritz-Blickwede, M, Thingholm, LB, Zheng, T, Assadi, G, Dierks, C, et al
Gut. 2018;67(2):263-270
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Congenital sucrase-isomaltase deficiency (CSID) is a genetic disorder which results in a lower ability to digest certain sugars, resulting in diarrhoea, abdominal pain and bloating, which are also common symptoms of Irritable Bowel Syndrome (IBS). The objective of this study was to test sucrase-isomaltase (SI) gene variants for their potential relevance in IBS. The researchers looked at genetics in several populations with and without IBS. The researchers found that genetic mutations are associated with a 35% reduction in the activity of the SI enzymes. CSID mutations were almost twice as common in IBS patients than healthy controls. The genetic variant 15Phe was associated with diarrhoea, stool frequency and changes in the gut bacteria. The authors concluded that people with SI gene variants associated with reduced enzyme activity are more at risk of IBS. Genetic screening could help to identify individuals at increased risk of IBS, and may lead to more targeted treatment for some people with IBS.
Abstract
OBJECTIVE IBS is a common gut disorder of uncertain pathogenesis. Among other factors, genetics and certain foods are proposed to contribute. Congenital sucrase-isomaltase deficiency (CSID) is a rare genetic form of disaccharide malabsorption characterised by diarrhoea, abdominal pain and bloating, which are features common to IBS. We tested sucrase-isomaltase (SI) gene variants for their potential relevance in IBS. DESIGN We sequenced SI exons in seven familial cases, and screened four CSID mutations (p.Val557Gly, p.Gly1073Asp, p.Arg1124Ter and p.Phe1745Cys) and a common SI coding polymorphism (p.Val15Phe) in a multicentre cohort of 1887 cases and controls. We studied the effect of the 15Val to 15Phe substitution on SI function in vitro. We analysed p.Val15Phe genotype in relation to IBS status, stool frequency and faecal microbiota composition in 250 individuals from the general population. RESULTS CSID mutations were more common in patients than asymptomatic controls (p=0.074; OR=1.84) and Exome Aggregation Consortium reference sequenced individuals (p=0.020; OR=1.57). 15Phe was detected in 6/7 sequenced familial cases, and increased IBS risk in case-control and population-based cohorts, with best evidence for diarrhoea phenotypes (combined p=0.00012; OR=1.36). In the population-based sample, 15Phe allele dosage correlated with stool frequency (p=0.026) and Parabacteroides faecal microbiota abundance (p=0.0024). The SI protein with 15Phe exhibited 35% reduced enzymatic activity in vitro compared with 15Val (p<0.05). CONCLUSIONS SI gene variants coding for disaccharidases with defective or reduced enzymatic activity predispose to IBS. This may help the identification of individuals at risk, and contribute to personalising treatment options in a subset of patients.