Dietary n-3 and n-6 polyunsaturated fatty acid intake interacts with FADS1 genetic variation to affect total and HDL-cholesterol concentrations in the Doetinchem Cohort Study

Gene-environment interactions that influence CVD, lipid traits, obesity, diabetes, and hypertension appear to be able to influence gene therapy

Most mind boggling diseases are accepted to be impacted by both genetic and environmental elements. As of late, there has been a flood in the improvement of different methodologies, concentrate on plans, and measurable and logical techniques to examine gene-environment cooperations (G × Es) in enormous scope studies including human populaces. The many-sided exchange between genetic elements and environmental openings has long charmed the consideration of clinicians and researchers looking to grasp the complicated starting points of diseases. While single variables can add to disease, the blend of genetic variations and environmental openings frequently decides disease risk. The fundamental point of this paper is to talk about the Gene-Environment Associations That Impact CVD, Lipid Characteristics, Obesity, Diabetes, and Hypertension Have all the earmarks of being Ready to Impact Gene Therapy. This survey paper investigates the meaning of gene-environment collaborations (G × E) in disease advancement. The intricacy of genetic and environmental communications in disease causation is explained, underlining the multifactorial idea of many circumstances. The job of gene-environment cooperations in cardiovascular disease, lipid digestion, diabetes, obesity, and hypertension is investigated. This audit fixates on Gene by Environment (G × E) collaborations, investigating their importance in disease etiology.

Interaction among dietary n-3 and n-6 polyunsaturated fatty acid intake, fatty acid desaturase 2 genetic variants, and low-density lipoprotein cholesterol levels in type 2 diabetes patients

AIMS/INTRODUCTION

Fatty acid desaturase (FADS) genetic polymorphisms are strongly correlated with the risk of dyslipidemia and cardiovascular disease. In this study, we examined the impact of FADS1 and FADS2 genetic variants on plasma lipid status, and assessed interactions between FADS genetic polymorphisms and plasma n-3/n-6 fatty acids regarding lipid status within a population of 816 Taiwanese patients with type 2 diabetes.

MATERIALS AND METHODS

Selected tag single-nucleotide polymorphisms (FADS1 rs174546 [T/C]; FADS2 rs174602 [A/G] and rs2072114 [A/G]) were genotyped (n = 816).

RESULTS

The distribution of genotypes were compared with reports publicly available in the Genome Aggregation Database for East Asian populations (https://gnomad.broadinstitute.org). In the subgroup of patients not taking lipid-lowering medications (n = 192), we observed that the G allele of FADS2 rs174602 was statistically significantly correlated with lower low-density lipoprotein cholesterol (LDL-C) concentrations (P = 0.001), whereas the G allele of rs2072114 was marginally associated with LDL-C concentrations (P = 0.091). Using a general linear model adjusted for confounding factors, statistically significant interactions (P = 0.016) between single-nucleotide polymorphisms in rs2072114 and a low alpha-linolenic acid (18:3n-3)/linoleic acid (18:2n-6) ratio; the G allele correlated with lower LDL-C levels among individuals with a low alpha-linolenic acid/linoleic acid ratio. Interaction between rs174602 single-nucleotide polymorphisms and low alpha-linolenic acid/linoleic acid values on LDL-C was only marginally significant (P = 0.063).

CONCLUSIONS

Our results show the role of n-3/n-6 dietary polyunsaturated fatty acids in modifying the effects of genetic susceptibility on lipoprotein concentrations in patients with type 2 diabetes. Our findings highlight the potential of interventions with dietary polyunsaturated fatty acids regarding developing individualized prevention strategies for type 2 diabetes presenting with co-occurring dyslipidemia and cardiovascular diseases.

Single nucleotide polymorphism of fatty acid desaturase gene and breast cancer risk in estrogen receptor subtype

BACKGROUND

Breast cancer (BC) is the most common cancer of women and the second most common cancer overall globally. Data suggest that the plasma concentration of omega fatty acids (n-3 and n-6) and the impact of the genetic variant are associated with diet-related inflammatory disease, BC. This study was aimed to find an association between genetic variant rs174537 of fatty acid desaturase gene 1(FADS 1) and breast cancer estrogen receptor subtype.

METHODOLOGY

Hundred and two blood samples from women were quantified for fatty acids by gas chromatography. SNP rs 174537(G > T) showed maximum variability and the strongest genetic determinant in the Genome-wide association study were genotyped using Sanger sequencing.

RESULTS

The highest tertile of ALA showed a significantly reduced risk of BC compared to the lowest tertile (OR = 0.2, 95 %CL = 0.1-1.14, P = 0.03). Median values of ALA were higher in GT/TT genotype in ER +ve molecular subtype (P = 0.03) and DPA was higher in GG genotype of ER-ve molecular subtype (P = 0.037). When both the groups were put together the highest tertile of GG tertile showed significantly reduced risk of BC compared with the other lowest tertiles of GG and GT/TT genotypes (OR, 95% CL = 0.45(0.2-0.9).

CONCLUSION

The high levels of arachidonic acid and low levels of n-3 fatty acids result in a pro-inflammatory milieu and that these pro-inflammatory effects might contribute to BC. We conclude that the individuals with genetically determined lower activity of FADS1(minor allele T) will derive greater advantage from n-3 FAs than those with higher FADS1 activity (G allele) and reduce the BC risk.

Interactive effects of the low‐carbohydrate diet score and genetic risk score on Hypo‐HDL‐cholesterolemia among Korean adults: A cross‐sectional analysis from the Ansan and Ansung Study of the Korean Genome and Epidemiology Study

This cross‐sectional study investigated the interaction between the genetic risk score (GRS) and abnormal high‐density lipoprotein (HDL) cholesterol lipid levels, which are modified by low‐carbohydrate diets (LCDs) and their effects on the prevalence of hypo‐HDL‐cholesterolemia (hypo‐HDL‐C) in Korean adults. Baseline data were obtained from the Ansan and Ansung study of the Korean Genome and Epidemiology Study (KoGES), conducted from 2001 to 2002, that targeted 8,314 Korean adults aged 40–69 years, including old men (47.6%) and women (52.4%), and whole genomic single nucleotide polymorphism (SNP) genotyping was performed. We identified 18 SNPs significantly associated with hypo‐HDL‐C in the proximity of several genes, including LPL, APOA5, LIPC, and CETP, and calculated the GRS. The low‐carbohydrate diet score (LCDS) was calculated on the basis of energy intake information from food frequency questionnaires. Furthermore, we performed multivariable‐adjusted logistic modeling to examine the odds ratio (OR) for hypo‐HDL‐C across tertiles of LCDS and GRS, adjusted for several covariates. Among participants in the highest GRS tertile, those in the highest tertile of the LCDS had a significantly lower risk of hypo‐HDL‐C (OR: 0.759, 95% CI (confidence interval): 0.625–0.923) than those in the lowest tertile of the LCDS. In the joint effect model, the group with the lowest GRS and highest LCDS was found to have the lowest risk of hypo‐HDL‐C prevalence. This study suggests that individuals with a high genetic risk for low HDL concentrations may have a beneficial effect on a lower intake of carbohydrates.

Personalized Dietary Recommendations Based on Lipid-Related Genetic Variants: A Systematic Review

Background

Obesity and dyslipidemias are risk factors for developing cardiovascular diseases, the leading causes of morbidity and mortality worldwide. The pathogenesis of these diseases involves environmental factors, such as nutrition, but other aspects like genetic polymorphisms confer susceptibility to developing obesity and dyslipidemias. In this sense, nutrigenetics is being used to study the influence of genetic variations on the circulating lipid responses promoted by certain nutrients or foods to provide specific dietary strategies considering the genetic factors in personalized nutrition interventions.

Objective

To identify throughout a systematic review the potential nutrigenetic recommendations that demonstrate a strong interaction between gene-diet and circulating lipid variations.

Methods

This systematic review used the PRISMA-Protocol for manuscript research and preparation using PubMed and ScienceDirect databases. Human studies published in English from January 2010 to December 2020 were included. The main results were outcomes related to gene-diet interactions and plasmatic lipids variation.

Results

About 1,110 articles were identified, but only 38 were considered to fulfill the inclusion criteria established based on the reported data. The acquired information was organized based on gene-diet interaction with nutrients and components of the diet and dietary recommendation generated by each interaction: gene-diet interaction with dietary fats, carbohydrates or dietary fiber, gene-diet interaction with nutraceutical or dietary supplementation, and gene-diet interaction with proteins.

Conclusion

Findings included in this systematic review indicated that a certain percentage of dietary macronutrients, the consumption of specific amounts of polyunsaturated or monounsaturated fatty acids, as well as the ingestion of nutraceuticals or dietary supplements could be considered as potential strategies for the development of a wide range of nutrigenetic interventions since they have a direct impact on the blood levels of lipids. In this way, specific recommendations were identified as potential tools in developing precision diets and highlighted the importance of personalized nutrition. These recommendations may serve as a possible strategy to implement as dietary tools for the preventive treatment and control alterations in lipid metabolism.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021248816, identifier [CRD42021248816].

FADS1 and FADS2 Gene Polymorphisms Modulate the Relationship of Omega-3 and Omega-6 Fatty Acid Plasma Concentrations in Gestational Weight Gain: A NISAMI Cohort Study

The polymorphisms of fatty acid desaturase genes FADS1 and FADS2 have been associated with an increase in weight gain. We investigated FADS1 and FADS2 gene polymorphisms and the relation between ω-3 and ω-6 fatty acid plasma concentrations and gestational weight gain. A prospective cohort study of 199 pregnant women was followed in Santo Antônio de Jesus, Brazil. Plasma levels of polyunsaturated fatty acids (PUFAs) were measured at baseline and gestational weight gain during the first, second, and third trimesters. Fatty acid recognition was carried out with the aid of gas chromatography. Single nucleotide polymorphisms (SNPs) were genotyped using real-time PCR. Statistical analyses included Structural Equation Modelling. A direct effect of FADS1 and FADS2 gene polymorphisms on gestational weight was observed; however, only the SNP rs174575 (FADS2) showed a significant positive direct effect on weight over the course of the pregnancy (0.106; p = 0.016). In terms of the influence of SNPs on plasma levels of PUFAs, it was found that SNP rs174561 (FADS1) and SNP rs174575 (FADS2) showed direct adverse effects on plasma concentrations of ω-3 (eicosapentaenoic acid and alpha-linoleic acid), and only SNP rs174575 had positive direct effects on plasma levels of ARA and the ARA/LA (arachidonic acid/linoleic acid) ratio, ω-6 products, while the SNP rs3834458 (FADS2) had an adverse effect on plasma concentrations of EPA, leading to its increase. Pregnant women who were heterozygous and homozygous for the minor allele of the SNP rs3834458 (FADS2), on the other hand, showed larger concentrations of series ω-3 substrates, which indicates a protective factor for women’s health.

Nutrigenetics, omega-3 and plasma lipids/lipoproteins/apolipoproteins with evidence evaluation using the GRADE approach: a systematic review

OBJECTIVES

Despite the uptake of nutrigenetic testing through direct-to-consumer services and healthcare professionals, systematic reviews determining scientific validity are limited in this field. The objective of this review was to: retrieve, synthesise and assess the quality of evidence (confidence) for nutrigenetic approaches related to the effect of genetic variation on plasma lipid, lipoprotein and apolipoprotein responsiveness to omega-3 fatty acid intake.

DESIGN

A systematic review was conducted using three search engines (Embase, Web of Science and Medline) for articles published up until 1 August 2020. We aimed to systematically search, identify (select) and provide a narrative synthesis of all studies that assessed nutrigenetic associations/interactions for genetic variants (comparators) influencing the plasma lipid, lipoprotein and/or apolipoprotein response (outcomes) to omega-3 fatty acid intake (intervention/exposure) in humans-both paediatric and adult populations (population). We further aimed to assess the overall quality of evidence for specific priority nutrigenetic associations/interactions based on the following inclusion criteria: nutrigenetic associations/interactions reported for the same genetic variants (comparators) influencing the same plasma lipid, lipoprotein and/or apolipoprotein response (outcomes) to omega-3 fatty acid intake (intervention/exposure) in humans-both paediatric and adult populations (population) in at least two independent studies, irrespective of the findings. Risk of bias was assessed in individual studies. Evidence was evaluated using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach with a modification to further consider biological plausibility.

RESULTS

Out of 1830 articles screened, 65 met the inclusion criteria for the narrative synthesis (n=23 observational, n=42 interventional); of these, 25 met the inclusion criteria for GRADE evidence evaluation. Overall, current evidence is insufficient for gene-diet associations related to omega-3 fatty acid intake on plasma apolipoproteins, total cholesterol, high-density lipoprotein-cholesterol, low-density lipoprotein (LDL)-cholesterol and LDL particle size. However, there is strong (GRADE rating: moderate quality) evidence to suggest that male APOE-E4 carriers (rs429358, rs7412) exhibit significant triglyceride reductions in response to omega-3-rich fish oil with a dose-response effect. Moreover, strong (GRADE rating: high quality) evidence suggests that a 31-SNP nutrigenetic risk score can predict plasma triglyceride responsiveness to omega-3-rich fish oil in adults with overweight/obesity from various ethnicities.

CONCLUSIONS

Most evidence in this area is weak, but two specific nutrigenetic interactions exhibited strong evidence, with generalisability limited to specific populations.

PROSPERO REGISTRATION NUMBER

CRD42020185087.

Nutrigenetics and nutrigenomics-A personalized approach to nutrition

The prevalence of non-communicable diseases has been on an upward trajectory for some time and this puts an enormous burden on the healthcare expenditure. Lifestyle modifications including dietary interventions hold an immense promise to manage and prevent these diseases. Recent advances in genomic research provide evidence that focussing these efforts on individual variations in abilities to metabolize nutrients (nutrigenetics) and exploring the role of dietary compounds on gene expression (nutrigenomics and nutri-epigenomics) can lead to more meaningful personalized dietary strategies to promote optimal health. This chapter aims to provide examples on these gene-diet interactions at multiple levels to support the need of embedding targeted dietary interventions as a way forward to prevent, avoid and manage diseases.

A genetic sum score of effect alleles associated with serum lipid concentrations interacts with educational attainment

High-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and total cholesterol (TC) levels are influenced by both genes and the environment. The aim was to investigate whether education and income as indicators of socioeconomic position (SEP) interact with lipid-increasing genetic effect allele scores (GES) in a population-based cohort. Using baseline data of 4516 study participants, age- and sex-adjusted linear regression models were fitted to investigate associations between GES and lipids stratified by SEP as well as including GES×SEP interaction terms. In the highest education group compared to the lowest stronger effects per GES standard deviation were observed for HDL-C (2.96 mg/dl [95%-CI: 2.19, 3.83] vs. 2.45 mg/dl [95%-CI: 1.12, 3.72]), LDL-C (6.57 mg/dl [95%-CI: 4.73, 8.37] vs. 2.66 mg/dl [95%-CI: −0.50, 5.76]) and TC (8.06 mg/dl [95%-CI: 6.14, 9.98] vs. 4.37 mg/dl [95%-CI: 0.94, 7.80]). Using the highest education group as reference, interaction terms showed indication of GES by low education interaction for LDL-C (ß_{GES×Education}: −3.87; 95%-CI: −7.47, −0.32), which was slightly attenuated after controlling for GES_LDL-C×Diabetes interaction (ß_{GES×Education}: −3.42; 95%-CI: −6.98, 0.18). The present study showed stronger genetic effects on LDL-C in higher SEP groups and gave indication for a GES_LDL-C×Education interaction, demonstrating the relevance of SEP for the expression of genetic health risks.

Quantile-Dependent Expressivity and Gene-Lifestyle Interactions Involving High-Density Lipoprotein Cholesterol

BACKGROUND

The phenotypic expression of a high-density lipoprotein (HDL) genetic risk score has been shown to depend upon whether the phenotype (HDL-cholesterol) is high or low relative to its distribution in the population (quantile-dependent expressivity). This may be due to the effects of genetic mutations on HDL-metabolism being concentration dependent.

METHOD

The purpose of this article is to assess whether some previously reported HDL gene-lifestyle interactions could potentially be attributable to quantile-dependent expressivity.

SUMMARY

Seventy-three published examples of HDL gene-lifestyle interactions were interpreted from the perspective of quantile-dependent expressivity. These included interactive effects of diet, alcohol, physical activity, adiposity, and smoking with genetic variants associated with the ABCA1, ADH3, ANGPTL4, APOA1, APOA4, APOA5, APOC3, APOE, CETP, CLASP1, CYP7A1, GALNT2, LDLR, LHX1, LIPC, LIPG, LPL, MVK-MMAB, PLTP, PON1, PPARα, SIRT1, SNTA1,and UCP1genes. The selected examples showed larger genetic effect sizes for lifestyle conditions associated with higher vis-à-vis lower average HDL-cholesterol concentrations. This suggests these reported interactions could be the result of selecting subjects for conditions that differentiate high from low HDL-cholesterol (e.g., lean vs. overweight, active vs. sedentary, high-fat vs. high-carbohydrate diets, alcohol drinkers vs. abstainers, nonsmokers vs. smokers) producing larger versus smaller genetic effect sizes. Key Message: Quantile-dependent expressivity provides a potential explanation for some reported gene-lifestyle interactions for HDL-cholesterol. Although overall genetic heritability appears to be quantile specific, this may vary by genetic variant and environmental exposure.

Intake and metabolism of omega-3 and omega-6 polyunsaturated fatty acids: nutritional implications for cardiometabolic diseases

Prospective observational studies support the use of long-chain omega-3 polyunsaturated fatty acids (PUFAs) in the primary prevention of atherosclerotic cardiovascular disease; however, randomised controlled trials, have often reported neutral findings. There is a long history of debate about the potential harmful effects of a high intake of omega-6 PUFAs, although this idea is not supported by prospective observational studies or randomised controlled trials. Health effects of PUFAs might be influenced by Δ-5 and Δ-6 desaturases, the key enzymes in the metabolism of PUFAs. The activity of these enzymes and modulation by variants in encoding genes (FADS1-2-3 gene cluster) are linked to several cardiometabolic traits. This Review will further consider non-genetic determinants of desaturase activity, which have the potential to modify the availability of PUFAs to tissues. Finally, we discuss the consequences of altered desaturase activity in the context of PUFA intake, that is, gene-diet interactions and their clinical and public health implications.

FADS1 and FADS2 polymorphism are associated with changes in fatty acid concentrations after calorie-restricted Central European and Mediterranean diets

OBJECTIVE

In the present study, we tested whether calorie-restricted diets differing in their percentage of energy derived from monounsaturated fatty acids and carbohydrates can affect the metabolism of fatty acids (FAs) in postmenopausal women. Moreover, we examined whether polymorphisms of FADS1 and FADS2 are associated with these changes.

METHODS

Postmenopausal women (the mean age: 60.5 ± 5.0 y) were randomized for 16 weeks to two different calorie-restricted diets: a Central European diet (CED) or a Mediterranean diet (MED).

RESULTS

After the intervention, levels of most FAs in red blood cells decreased in both groups. The delta values for the 20:1n-9 and the 20:2n-6 levels differed between the CED and the MED (-1.55 ± 4.02 μg/mL vs 0.39 ± 4.11 μg/mL and -0.62 ± 10.93 μg/mL vs 3.06 ± 8.75 μg/mL; P < 0.05). Women in the CED group with at least one minor allele of FADS genes had greater decreases of α-linolenic acid, dihomo-γ-linolenic acid, total n-6, and total PUFA (by approximately 70%, 40%, 35%, and 35%, respectively) than did women with the major alleles. After the intervention, the change in the lipid accumulation product index was -28.28 ± 27.84 and -32.00 ± 78.55 in the CED and the MED group, respectively.

CONCLUSIONS

The effect of the dietary intervention on FA metabolism seems to depend mostly on calorie restriction, but not on type of diet. FADS1 and FADS2 gene polymorphisms can modify the response to the CED.

Association between Plasma N-6 Polyunsaturated Fatty Acids Levels and the Risk of Cardiovascular Disease in a Community-based Cohort Study

Most studies support that saturated fatty acid replacement with polyunsaturated fatty acids (PUFAs) may reduce the risk of cardiovascular diseases (CVDs) and put emphasis on the effects of N-3 PUFAs. The reported relationships between N-6 PUFAs and CVD risks vary. We aimed to examine the associations between N-6 PUFA concentrations and CVD risks. In this community-based prospective cohort study on CVD-free patients at baseline (N = 1835, age: 60.6 ± 10.5 years, women: 44.5%), we measured the fatty acid concentrations in the blood using gas chromatography. Four hundred twenty-four participants developed CVDs during follow up. The total N-6 PUFA concentration was inversely associated with the CVD risk, with a 48% lower risk in the highest N-6 PUFA concentration quartile (hazard ratio = 0.52; P for trend <0.001). The estimated population attributable risk of N-6 PUFAs indicated that approximately 20.7% of CVD events would have been prevented if the plasma N-6 PUFA concentration had been higher than the median value. The total N-6 PUFA concentration presented the highest net reclassification improvement (NRI = 7.2%, P = 0.03) for predicting incident CVD. Further studies on N-6 PUFAs, diet habits, and their relationships with healthcare are warranted.

Reverse gene-environment interaction approach to identify variants influencing body-mass index in humans

Identifying gene-environment interactions (GxEs) contributing to human cardiometabolic disorders is challenging. Here we apply a reverse GxE candidate search by deriving candidate variants from promoter-enhancer interactions that respond to dietary fatty acid challenge through altered chromatin accessibility in human primary adipocytes. We then test all variants residing in the lipid-responsive open chromatin sites within adipocyte promoter-enhancer contacts for interaction effects between the genotype and dietary saturated fat intake on body mass index (BMI) in the UK Biobank. We discover 14 novel GxE variants in 12 lipid-responsive promoters, including well-known lipid genes (LIPE, CARM1, and PLIN2) and novel genes, such as LDB3, for which we provide further functional and integrative genomics evidence. We further identify 24 GxE variants in enhancers, totaling 38 new GxE variants for BMI in the UK Biobank, demonstrating that molecular genomics data produced in physiologically relevant contexts can discover new functional GxE mechanisms in humans.

Nutrigenetic Contributions to Dyslipidemia: A Focus on Physiologically Relevant Pathways of Lipid and Lipoprotein Metabolism

Cardiovascular disease (CVD) remains the number one cause of death worldwide, and dyslipidemia is a major predictor of CVD mortality. Elevated lipid concentrations are the result of multiple genetic and environmental factors. Over 150 genetic loci have been associated with blood lipid levels. However, not all variants are present in pathways relevant to the pathophysiology of dyslipidemia. The study of these physiologically relevant variants can provide mechanistic understanding of dyslipidemia and identify potential novel therapeutic targets. Additionally, dietary fatty acids have been evidenced to exert both positive and negative effects on lipid profiles. The metabolism of both dietary and endogenously synthesized lipids can be affected by individual genetic variation to produce elevated lipid concentrations. This review will explore the genetic, dietary, and nutrigenetic contributions to dyslipidemia.

FADS1-FADS2 genetic polymorphisms are associated with fatty acid metabolism through changes in DNA methylation and gene expression

Background

Genome-wide association studies (GWASs) have shown that genetic variants are important determinants of free fatty acid levels. The mechanisms underlying the associations between genetic variants and free fatty acid levels are incompletely understood. Here, we aimed to identify genetic markers that could influence diverse fatty acid levels in a Chinese population and uncover the molecular mechanisms in terms of DNA methylation and gene expression.

Results

We identified strong associations between single-nucleotide polymorphisms (SNPs) in the fatty acid desaturase (FADS) region and multiple polyunsaturated fatty acids. Expression quantitative trait locus (eQTL) analysis of rs174570 on FADS1 and FADS2 mRNA levels proved that minor allele of rs174570 was associated with decreased FADS1 and FADS2 expression levels (P < 0.05). Methylation quantitative trait locus (mQTL) analysis of rs174570 on DNA methylation levels in three selected regions of FADS region showed that the methylation levels at four CpG sites in FADS1, one CpG site in intragenic region, and three CpG sites in FADS2 were strongly associated with rs174570 (P < 0.05). Then, we demonstrated that methylation levels at three CpG sites in FADS1 were negatively associated with FADS1 and FADS2 expression, while two CpG sites in FADS2 were positively associated with FADS1 and FADS2 expression. Using mediation analysis, we further show that the observed effect of rs174570 on gene expression was tightly correlated with the effect predicted through association with methylation.

Conclusions

Our findings suggest that genetic variants in the FADS region are major genetic modifiers that can regulate fatty acid metabolism through epigenetic gene regulation.

Electronic supplementary material

The online version of this article (10.1186/s13148-018-0545-5) contains supplementary material, which is available to authorized users.

Association of Polymorphism in Fatty Acid Desaturase Gene with the Risk of Type 2 Diabetes in Iranian Population

Background:

The type 2 diabetes is one of the most common autoimmune diseases. Due to a key role in the metabolism of unsaturated fatty acids such as arachidonic acid, one of the most important precursors of immunity mediators, fatty acid desaturase (FADS) genes could have an important impact in the development of type 2 diabetes.

Materials and Methods:

This study aimed to determine the relationship between polymorphisms rs174537 in FADS1 gene and rs174575 in FADS2 gene with type 2 diabetes in Iranian population. After extracting genomic DNA, the locations of mutations and allele types were identified with high-resolution melting (HRM)-polymerase chain reaction method. Then, association between these mutations with metabolic syndrome, dyslipidemia, and type 2 diabetes was investigated using χ² correlation coefficients for variables and logistic regression.

Results:

The results showed that among 50 diabetic participants, 68% of patients have the mutant allele for rs174537 in FADS1 gene. This rate is 26% for rs174575 in FADS2 gene. Based on the results, it seems that participants having rs174537 mutant allele are more prone to become diabetic but it has a beneficial effect on total and low-density lipoprotein cholesterol and participants having rs174575 mutant are less prone to become diabetic, and also, it leads to higher triglycerides and body mass index (obesity).

Conclusions:

Detecting FADS1 and FADS2, gene polymorphisms using HRM can be an anticipating tool for making decision on initiating lifestyle modifications to prevent type 2 diabetes.

A regulatory insertion-deletion polymorphism in the FADS gene cluster influences PUFA and lipid profiles among Chinese adults: a population-based study

Background

Arachidonic acid (AA) is the major polyunsaturated fatty acid (PUFA) substrate for potent eicosanoid signaling to modulate inflammation and thrombosis and is controlled in part by tissue abundance. Fatty acid desaturase 1 (FADS1) catalyzes synthesis of omega-6 (n-3) AA and n-3 eicosapentaenoic acid (EPA). The rs66698963 polymorphism, a 22-base pair (bp) insertion-deletion 137 bp downstream of a sterol regulatory element in FADS2 intron 1, mediates expression of FADS1 in vitro, as well as exerting positive selection in several human populations. The associations between the polymorphism rs66698963 and plasma PUFAs as well as disease phenotypes are unclear.

Objective

This study aimed to evaluate the relation between rs66698963 genotypes and plasma PUFA concentrations and blood lipid profiles.

Design

Plasma fatty acids were measured from a single sample obtained at baseline in 1504 healthy Chinese adults aged between 35 and 59 y with the use of gas chromatography. Blood lipids were measured at baseline and a second time at the 18-mo follow-up. The rs66698963 genotype was determined by using agarose gel electrophoresis. Linear regression and logistic regression analyses were performed to assess the association between genotype and plasma PUFAs and blood lipids.

Results

A shift from the precursors linoleic acid and α-linolenic acid to produce AA and EPA, respectively, was observed, consistent with FADS1 activity increasing in the order of genotypes D/D to I/D to I/I. For I/I compared with D/D carriers, plasma concentrations of n-6 AA and the ratio of AA to n-3 EPA plus docosahexaenoic acid (DHA) were 57% and 32% higher, respectively. Carriers of the deletion (D) allele of rs66698963 tended to have higher triglycerides (β = 0.018; SE: 0.009; P = 0.05) and lower HDL cholesterol (β = -0.008; SE: 0.004; P = 0.02) than carriers of the insertion (I) allele.

Conclusions

The rs66698963 genotype is significantly associated with AA concentrations and AA to EPA+DHA ratio, reflecting basal risk of inflammatory and related chronic disease phenotypes, and is correlated with the risk of dyslipidemia. This trial was registered at chictr.org.cn as ChiCTR-EOC-17012759.

Serum Lipid Concentrations and FADS Genetic Variants in Young Mexican College Students: The UP-AMIGOS Cohort Study

BACKGROUND

Recent genome-wide association studies in the Mexican population have identified several genetic loci associated with blood lipid levels in adults. However, studies focusing on the fatty acid desaturase (FADS) gene cluster have been understudied in this population, even though it seems associated with lipid profiles in other ethnicities. The aim of this study was to test associations between single nucleotide polymorphisms (SNPs) in the FADS cluster (rs174546, rs1535, rs174548, rs174550, rs174450, and rs174618) and serum lipid profiles in young Mexicans.

METHODS

Anthropometrics, serum lipid profiles, and FADS SNPs were measured in 998 subjects in the UP-AMIGOS cohort study. Genotype-phenotype (total cholesterol [TC], triglyceride [TG], high-density lipoprotein cholesterol [HDL-C], low-density lipoprotein cholesterol [LDL-C], and very-low-density lipoprotein [VLDL]) associations were assessed using PLINK adjusted for sex, age, and body mass index (BMI).

RESULTS

Among 6 FADS SNPs, we found that carriers of the C-allele of the FADS1-rs174546 showed a significant association with lower TG concentrations (β = -12.6 mg/dL, p = 0.009) and lower VLDL concentrations (β = -2.52 mg/dL, p = 0.005). We found that rs174546, rs1535, and rs174550 were in high linkage disequilibrium (r2 > 0.80). There were no significant associations between rs174550, rs174548, and rs174618 and lipid profiles.

CONCLUSION

A genetic variant in the FADS1 (rs174546) gene is a major contributor of plasma TG and VLDL concentrations in healthy young Mexicans.

The combined effects of FADS gene variation and dietary fats in obesity-related traits in a population from the far north of Sweden: the GLACIER Study

Background

Recent analyses in Greenlandic Inuit identified six genetic polymorphisms (rs74771917, rs3168072, rs12577276, rs7115739, rs174602, and rs174570) in the fatty acid desaturase gene cluster (FADS1-FADS2-FADS3) that are associated with multiple metabolic and anthropometric traits. Our objectives were to systematically assess whether dietary polyunsaturated fat acid (PUFA) intake modifies the associations between genetic variants in the FADS gene cluster and cardiometabolic traits and to functionally annotate top ranking candidates to estimate their regulatory potential.

Methods

Data analyses consisted: interaction analyses between the six candidate genetic variants and dietary PUFA intake; gene-centric joint analyses to detect interaction signals in the FADS region; haplotype block-centric joint tests across 30 haplotype blocks in the FADS region to refine interaction signals; functional annotation of top loci. These analyses were undertaken in Swedish adults from the GLACIER Study (N=5,160); data on genetic variation and eight cardiometabolic traits was used.

Results

Interactions were observed between rs174570 and n-6 PUFA intake on fasting glucose (P_int=0.005) and between rs174602 and n-3 PUFA intake on total cholesterol (P_int=0.001). Gene-centric analyses demonstrated a statistically significant interaction effect for FADS and n-3 PUFA on triglycerides (P=0.005) considering genetic main effects as random. Haplotype analyses revealed three blocks (P_int<0.011) that could drive the interaction between FADS and n-3 PUFA on triglycerides; Functional annotation of these regions showed that each block harbours a number of highly functional regulatory variants; FADS2 rs5792235 demonstrated the highest functionality score.

Conclusions

The association between FADS variants and triglycerides may be modified by PUFA intake. The intronic FADS2 rs5792235 variant is a potential causal variant in the region having the highest regulatory potential. However, our results suggest that haplotypes may harbour multiple functional variants in a region, rather than a single variant.

Dietary linoleic acid interacts with FADS1 genetic variability to modulate HDL-cholesterol and obesity-related traits

BACKGROUND & AIMS

Blood levels of polyunsaturated fatty acids (PUFAs) are under control of endogenous synthesis via Δ5- and Δ6-desaturases, encoded by the FADS1 and FADS2 genes, respectively and of diet. Genome-wide associations studies (GWAS) reported associations between polymorphisms in FADS1-FADS2 and variations in plasma concentrations of PUFAs, HDL- and LDL-cholesterol and triglycerides. However, it is not established whether dietary PUFAs intake modulates these associations. We assessed whether dietary linoleic acid (LA) or α-linolenic acid (ALA) modulate the association between the FADS1 rs174547 polymorphism (a GWAS hit) and lipid and anthropometric phenotypes.

METHODS

Dietary intakes of LA and ALA, FADS1 rs174547 genotypes, lipid and anthropometric variables were determined in three French population-based samples (n = 3069). These samples were stratified according to the median dietary LA (<9.5 and ≥9.5 g/d) and ALA (<0.80 and ≥0.80 g/d) intakes. The meta-analysis was performed using a random-effect.

RESULTS

Our meta-analysis confirmed the association between rs174547 and plasma lipid levels and revealed an association with waist circumference and body mass index. These associations were not modified by dietary ALA intake (all p-interaction > 0.05). In contrast, the associations with HDL-cholesterol levels, waist circumference and BMI were modulated by the dietary intake of LA (p interaction < 0.05). In high LA consumers only, the rs174547 minor allele was significantly associated with lower HDL-cholesterol levels (β = -0.05 mmol/L, p = 0.0002). Furthermore, each copy of the rs174547 minor allele was associated with a 1.58 cm lower waist circumference (p = 0.0005) and a 0.46 kg m^-2 lower BMI (p = 0.01) in the low LA intake group, but not in the high LA intake group.

CONCLUSIONS

The present study suggests that dietary LA intake may modulate the association between the FADS gene variants and HDL-cholesterol concentration, waist circumference and BMI. These gene-nutrient interactions, if confirmed, suggest that subjects carrying the rs174547 minor allele might benefit from low dietary LA intakes.

FADS Gene Polymorphisms, Fatty Acid Desaturase Activities, and HDL-C in Type 2 Diabetes

Polyunsaturated fatty acids (PUFA) correlate with risk of dyslipidemia and cardiovascular diseases. Fatty acid desaturase (FADS) single nucleotide polymorphisms (SNPs) modulate circulating PUFA concentrations. This study examined influence of FADS1 and FADS2 genetic variants on desaturase activities and blood lipid concentrations in type 2 diabetes patients, and further assessed their interrelationships. Selected SNPs (FADS1: rs174547, rs174548, rs174550; FADS2: rs174575, rs174576, rs174583, rs498793 and rs2727270) were genotyped in 820 type 2 diabetes patients and compared with those reported in the HapMap. Patient subgroups (n = 176) without taking lipid-lowering medicine were studied to assess influence of tag SNPs including rs174547, rs174575, rs498793 and rs2727270 on delta-5 desaturase (D5D: 20:4 (n-6)/20:3 (n-6)) and delta-6 desaturase (D6D:18:3 (n-6)/18:2 (n-6)) activities, and blood lipids. FADS1 rs174547 TT/TC/CC and FADS2 rs2727270 CC/CT/TT were significantly (p for trend < 0.05) associated with reduced HDL-C, D5D and D6D activities. Upon adjustment for confounders, D5D (p = 0.006) correlated significantly and D6D marginally (p = 0.07) correlated with increased HDL-C levels, whereas rs174547 and rs2727270 polymorphisms were not associated. D6D andD5D activities may play a role in modulating HDL-C levels in type 2 diabetes. Future studies with larger sample sizes are needed to investigate how FADS genetic variations interact with desaturase activities or PUFAs in the metabolism of lipoproteins in diabetic patients.

Association of the FADS gene cluster with coronary artery disease and plasma lipid concentrations in the northern Chinese Han population

We investigated the association of single nucleotide polymorphisms (SNPs) in the fatty acid desaturase (FADS) gene cluster with coronary artery disease (CAD) in a case-control study and evaluated the possible influence of genetic variation on total cholesterol (TC) and triglyceride concentrations in the controls. In total, 497 CAD patients and 495 unrelated controls were genotyped for eight SNPs in the FADS gene cluster, and the blood lipid levels of subjects were measured. Three genetic models, including codominant, dominant and recessive, were used to analyze the genotypic relationship with CAD and plasma lipid levels. Single locus genotypic analysis revealed that rs1000778 in FADS3 under a recessive model (AA vs. GG-GA) was significantly associated with CAD adjusted for risk factors. The rs1000778 minor allele AA was associated with a lower risk of CAD (OR =0.37, 95% CI: 0.15-0.89, P=0.025). In the control group, there were significant differences in TC concentrations under a recessive genetic model for rs174575 (C/G) in FADS2 and for rs174450 (A/C) and rs7115739 (G/T) in FADS3 (P=0.053, 0.016 and 0.018, respectively). The rs1000778-G variant in FADS3 may contribute to the susceptibility of CAD, but the result needs to be further confirmed because of small sample size in our study. Genetic variations in FADS2 and FADS3 influence TC concentration in the northern Chinese Han population.

The impact of fatty acid desaturase genotype on fatty acid status and cardiovascular health in adults

The aim of this review was to determine the impact of the fatty acid desaturase (FADS) genotype on plasma and tissue concentrations of the long-chain (LC) n-3 PUFA, including EPA and DHA, which are associated with the risk of several diet-related chronic diseases, including CVD. In addition to dietary intakes, which are low for many individuals, tissue EPA and DHA are also influenced by the rate of bioconversion from α-linolenic acid (αLNA). Δ-5 and Δ-6 desaturase enzymes, encoded for by FADS1 and FADS2 genes, are key desaturation enzymes involved in the bioconversion of essential fatty acids (αLNA and linoleic acid (LA)) to longer chained PUFA. In general, carriers of FADS minor alleles tend to have higher habitual plasma and tissue levels of LA and αLNA, and lower levels of arachidonic acid, EPA and also to a lesser extent DHA. In conclusion, available research findings suggest that FADS minor alleles are also associated with reduced inflammation and CVD risk, and that dietary total fat and fatty acid intake have the potential to modify relationships between FADS gene variants and circulating fatty acid levels. However to date, neither the size-effects of FADS variants on fatty acid status, nor the functional SNP in FADS1 and 2 have been identified. Such information could contribute to the refinement and targeting of EPA and DHA recommendations, whereby additional LC n-3 PUFA intakes could be recommended for those carrying FADS minor alleles.

FADS1-FADS2 gene cluster confers risk to polycystic ovary syndrome

Dyslipidemia is common in polycystic ovary syndrome (PCOS). This study was aimed to investigate whether fatty acid desaturase genes (FADS), a dyslipidemia-related gene cluster, are associated with PCOS. We scanned variations of FADS genes using our previous data of genome-wide association study (GWAS) for PCOS and selected rs174570 for further study. The case-control study was conducted in an independent cohort of 1918 PCOS cases and 1889 age-matched controls and family-based study was conducted in a set of 243 core family trios with PCOS probands. Minor allele frequency (allele T) of rs174570 was significantly lower in PCOS cases than that in age-matched controls (P = 2.17E-03, OR = 0.85), even after adjustment of BMI and age. PCOS subjects carrying CC genotype had higher testosterone level and similar lipid/glucose level compared with those carrying TT or TC genotype. In trios, transmission disequilibrium test (TDT) analysis revealed risk allele C of rs174570 was significantly over-transmitted (P = 2.00E-04). Decreased expression of FADS2 was detected in PCOS cases and expression quantitative trait loci (eQTL) analysis revealed the risk allele C dosage was correlated with the decline of FADS2 expression (P = 0.002). Our results demonstrate that FADS1-FADS2 are susceptibility genes for PCOS.

Biochemical insights from population studies with genetics and metabolomics

Genome-wide association studies with concentrations of hundreds of small molecules in samples collected from thousands of individuals (mGWAS) access otherwise inaccessible natural genetic experiments and their influence on the metabolic capacities of the human body. By sampling the natural metabolic and genetic variability that is present in the general population, mGWAS identified over 150 associations between genetic variants and variation in the metabolic composition of human body fluids. Many of these genetic variants were found to be located in enzyme or transporter coding genes, whose functions match the biochemical nature of the associated metabolites. Associations identified by mGWAS can reveal novel biochemical knowledge, such as the function of uncharacterized genes, the biochemical identity of small molecules, and the structure of entire biochemical pathways. Here we review findings of recent mGWAS and discuss concrete examples of how their results can be interpreted in a biochemical context. We describe online resources that are available for mining mGWAS results. In this context, we present two concepts that also find more general applications in the field of metabolomics: strengthening of associations by looking at ratios between metabolite pairs and reconstruction of metabolic pathways by Gaussian graphical modeling.

Genetic Contribution of Variants near SORT1 and APOE on LDL Cholesterol Independent of Obesity in Children

Objective

To assess potential effects of variants in six lipid modulating genes (SORT1, HMGCR, MLXIPL, FADS2, APOE and MAFB) on early development of dyslipidemia independent of the degree of obesity in children, we investigated their association with total (TC), low density lipoprotein (LDL-C), high density lipoprotein (HDL-C) cholesterol and triglyceride (TG) levels in 594 children. Furthermore, we evaluated the expression profile of the candidate genes during human adipocyte differentiation.

Results

Expression of selected genes increased 10¹ to >10⁴ fold during human adipocyte differentiation, suggesting a potential link with adipogenesis. In genetic association studies adjusted for age, BMI SDS and sex, we identified significant associations for rs599839 near SORT1 with TC and LDL-C and for rs4420638 near APOE with TC and LDL-C. We performed Bayesian modelling of the combined lipid phenotype of HDL-C, LDL-C and TG to identify potentially causal polygenic effects on this multi-dimensional phenotype and considering obesity, age and sex as a-priori modulating factors. This analysis confirmed that rs599839 and rs4420638 affect LDL-C.

Conclusion

We show that lipid modulating genes are dynamically regulated during adipogenesis and that variants near SORT1 and APOE influence lipid levels independent of obesity in children. Bayesian modelling suggests causal effects of these variants.

Dietary n-3 polyunsaturated fatty acid intakes modify the effect of genetic variation in fatty acid desaturase 1 on coronary artery disease

BACKGROUND

Previous studies suggested that dietary fatty acids could affect blood lipids by interacting with genetic variations in fatty acid desaturase 1 (FADS1). However, little is known about their direct effects on coronary artery disease (CAD). The aim of this study was to evaluate whether dietary n-3 long-chain polyunsaturated fatty acids (LCPUFAs)-eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) could modulate the effect of FADS1 rs174547 polymorphism on CAD.

METHODS

FADS1 single-nucleotide polymorphisms rs174547 genotypes were measured in 440 CAD patients and 838 healthy controls. Dietary EPA and DHA intakes were assessed with a validated quantitative frequency food questionnaire. The association between FADS1 rs174547 and CAD was estimated using logistic regression under both dominant and additive genetic models. The interactions between rs174547 polymorphism and LCPUFAs were analyzed by using multiple logistic regression and the "genotype × n-3 LCPUFAs" interaction term was included into the model.

RESULTS

We found that the minor T allele of FADS1 rs174547 increased CAD risk (OR = 1.36, 95%CIs 1.03-1.80), and observed significant interaction between rs174547 and dietary EPA intakes on CAD (P-interaction = 0.028). The T-allele was only associated with higher CAD risk among individuals with lower dietary EPA intakes, but not in those with higher EPA intakes. Similarly, significant interaction was also observed between rs174547 and dietary DHA intakes on CAD (P-interaction = 0.020).

CONCLUSIONS

Dietary n-3 LCPUFA intakes could modulate the association between FADS1 rs174547 polymorphism and CAD. High dietary n-3 LCPUFA intakes could negate the unfavorable effect of genetic variation in FADS1 on CAD in middle-aged and elderly Chinese population.

Gene-environment interaction in dyslipidemia

PURPOSE OF REVIEW

Recent genome-wide association studies have identified numerous common genetic variants associated with plasma lipid traits and have provided new insights into the regulation of lipoprotein metabolism including the identification of novel biological processes. These findings add to a body of existing data on dietary and environmental factors affecting plasma lipids. Here we explore how interactions between genetic risk factors and other phenotypes may explain some of the missing heritability of plasma lipid traits.

RECENT FINDINGS

Recent studies have identified true statistical interaction between several environmental and genetic risk factors and their effects on plasma lipid fractions. These include interactions between behaviors such as smoking or exercise as well as specific dietary nutrients and the effect size of specific genetic variants on plasma lipid traits risk and modifying effects of measures of adiposity on the cumulative impact of a number of common genetic variants on each of plasma triglycerides and HDL cholesterol.

SUMMARY

Interactions between genetic risk factors and clinical phenotypes may account for some of the unexplained heritability of plasma lipid traits. Recent studies provide biological insight into specific genetic associations and may aid in the identification of dyslipidemic patients for whom specific lifestyle interventions are likely to be most effective.

Beneficial effects of ω-3 PUFA in children on cardiovascular risk factors during childhood and adolescence

Omega-3 polyunsatured fatty acids (ω-3 PUFA) are essential nutrients mainly derived from fish and seafood but present also in vegetables such as nuts and seed-oils. Some epidemiological and clinical studies indicate a protection of ω-3 FA against cardiovascular disease and a favourable effect on cardiovascular risk factors control in adults. The evidences of their effects in children and adolescents are scanty but a possible beneficial role, especially for insulin sensitivity and blood pressure control, has been proposed. In this review we want to focus especially on the evidences, which could justify the assumption of ω-3 in children and adolescents, and to underline the aspects which need further investigation. Mechanisms through which ω-3 FA act are manifolds and still a matter of investigation: beside their interaction with ion channel and their influence on plasma membrane fluidity, probably the main effect is acting as competitor for cytochrome P-450 (CYP) with respect to ω-6 FA. Thus, they can modulate the biosynthesis of eicosanoids and other lipid mediators, which likely exert a protective action. Another suggestive hypothesis is that their beneficial effect is not dependent only on the intake of ω-3 FA, but also on the complex interaction between different nutrients including ω-3 and other FAs with polymorphisms in genes involved in ω-3 FA modulation. This complex interaction has seldom been explored in children and adolescents. Further studies are needed to investigate all these points in order to find a better collocation of ω-3 FA on the available armamentarium for preventive, possibly individualized, medicine.

Genetic loci associated with circulating phospholipid trans fatty acids: a meta-analysis of genome-wide association studies from the CHARGE Consortium

BACKGROUND

Circulating trans fatty acids (TFAs), which cannot be synthesized by humans, are linked to adverse health outcomes. Although TFAs are obtained from diet, little is known about subsequent influences (e.g., relating to incorporation, metabolism, or intercompetition with other fatty acids) that could alter circulating concentrations and possibly modulate or mediate impacts on health.

OBJECTIVE

The objective was to elucidate novel biologic pathways that may influence circulating TFAs by evaluating associations between common genetic variation and TFA biomarkers.

DESIGN

We performed meta-analyses using 7 cohorts of European-ancestry participants (n = 8013) having measured genome-wide variation in single-nucleotide polymorphisms (SNPs) and circulating TFA biomarkers (erythrocyte or plasma phospholipids), including trans-16:1n-7, total trans-18:1, trans/cis-18:2, cis/trans-18:2, and trans/trans-18:2. We further evaluated SNPs with genome-wide significant associations among African Americans (n = 1082), Chinese Americans (n = 669), and Hispanic Americans (n = 657) from 2 of these cohorts.

RESULTS

Among European-ancestry participants, 31 SNPs in or near the fatty acid desaturase (FADS) 1 and 2 cluster were associated with cis/trans-18:2; a top hit was rs174548 (β = 0.0035, P = 4.90 × 10(-15)), an SNP previously associated with circulating n-3 and n-6 polyunsaturated fatty acid concentrations. No significant association was identified for other TFAs. rs174548 in FADS1/2 was also associated with cis/trans-18:2 in Hispanic Americans (β = 0.0053, P = 1.05 × 10(-6)) and Chinese Americans (β = 0.0028, P = 0.002) but not African Americans (β = 0.0009, P = 0.34); however, in African Americans, fine mapping identified a top hit in FADS2 associated with cis/trans-18:2 (rs174579: β = 0.0118, P = 4.05 × 10(-5)). The association between rs174548 and cis/trans-18:2 remained significant after further adjustment for individual circulating n-3 and n-6 fatty acids, except arachidonic acid. After adjustment for arachidonic acid concentrations, the association between rs174548 and cis/trans-18:2 was nearly eliminated in European-ancestry participants (β-coefficient reduced by 86%), with similar reductions in Hispanic Americans and Chinese Americans.

CONCLUSIONS

Our findings provide novel evidence for genetic regulation of cis/trans-18:2 by the FADS1/2 cluster and suggest that this regulation may be influenced/mediated by concentrations of arachidonic acid, an n-6 polyunsaturated fat.

Omega-3 fatty acids and the genetic risk of early onset acute coronary syndrome

BACKGROUND AND AIMS

Recent gene-environment interaction studies suggest that diet may influence an individual's genetic predisposition to cardiovascular risk. We evaluated whether omega-3 fatty acid intake may influence the risk for acute coronary syndrome (ACS) conferred by genetic polymorphisms among patients with early onset ACS.

METHODS AND RESULTS

Our population consisted of 705 patients of white European descent enrolled in GENESIS-PRAXY, a multicenter cohort study of patients aged 18-55 years and hospitalized with ACS. We used a case-only design to investigate interactions between the omega-3 index (a validated biomarker of omega-3 fatty acid intake) and 30 single nucleotide polymorphisms (SNPs) robustly associated with ACS. We used logistic regression to assess the interaction between each SNP and the omega-3 index. Interaction was also assessed between the omega-3 index and a genetic risk score generated from the 30 SNPs. All models were adjusted for age and sex. An interaction for increased ACS risk was found between carriers of the chromosome 9p21 variant rs4977574 and low omega-3 index (OR 1.57, 95% CI 1.07-2.32, p = 0.02), but this was not significant after correction for multiple testing. Similar results were obtained in the adjusted model (OR 1.55, 95% CI 1.05-2.29, p = 0.03). We did not observe any interaction between the genetic risk score or any of the other SNPs and the omega-3 index.

CONCLUSION

Our results suggest that omega-3 fatty acid intake may modify the genetic risk conferred by chromosome 9p21 variation in the development of early onset ACS and requires independent replication.

Endogenous Production of Long-Chain Polyunsaturated Fatty Acids and Metabolic Disease Risk

Long chain polyunsaturated fatty acids (PUFAs) are important structural components of cellular membranes and are converted into eicosanoids which serve various biological roles. The most common dietary n-6 and n-3 PUFAs are linoleic acid and α-linoleic acid, respectively. These 18-carbon chain fatty acids undergo a series of desaturation and elongation steps to become the 20-carbon fatty acids arachidonic acid and eicosapentaenoic acid, respectively. Evidence from genome wide association studies has consistently demonstrated that plasma and tissue levels of the n-6 long-chain PUFA arachidonic acid and to a lesser extent the n-3 long-chain PUFA eicosapentaenoic acid, are strongly influenced by variation in fatty acid desaturase-1,-2, and elongation of very long chain fatty acid genes. Studies of functional variants in these genes, as well as studies in which desaturase activity has been indirectly estimated by fatty acid product-to -precursor ratios, have suggested that endogenous capacity to synthesize long-chain PUFAs may be associated with metabolic diseases such as diabetes mellitus. Interventional studies are starting to tease out the complicated relationship between dietary intakes of specific fatty acids, variation in desaturase and elongase genes and tissue levels of long chain PUFAs. Thus future studies of dietary PUFA interventions designed to reduce inflammatory and metabolic diseases will need to carefully consider how an individual's genetically-determined endogenous long-chain PUFA synthesis capacity might modify therapeutic response.

Genetic variation in FADS1 has little effect on the association between dietary PUFA intake and cardiovascular disease

The unclear link between intake of polyunsaturated fatty acids (PUFAs) and risk of cardiovascular disease (CVD) could depend on genetic differences between individuals. Minor alleles of single-nucleotide polymorphisms (SNPs) in the ∆5 fatty acid desaturase (FADS) 1 gene were associated with lower blood concentrations of long-chain ω-3 (n-3) and ω-6 (n-6) PUFAs, indicating an associated loss of function effect. We examined whether the SNP rs174546 in FADS1 modifies the association between PUFA intakes and CVD risk. We included 24,032 participants (62% women, aged 44-74 y) from the Malmö Diet and Cancer cohort without prevalent CVD and diabetes. During a mean follow-up of 14 y, 2648 CVD cases were identified. Diet was assessed by a modified diet history method. A borderline interaction was observed between the α-linolenic acid (ALA) (18:3n-3)-to-linoleic acid (LA) (18:2n-6) intake ratio and FADS1 genotype on CVD incidence (P = 0.06). The ALA-to-LA intake ratio was inversely associated with CVD risk only among participants homozygous for the minor T-allele (HR for quintile 5 vs. quintile 1 = 0.72; 95% CI: 0.50, 1.04; P-trend = 0.049). When excluding participants reporting unstable food habits in the past (35%), the interaction between the ALA-to-LA intake ratio and FADS1 genotype on CVD incidence was strengthened and statistically significant (P = 0.04). Additionally, we observed a significant interaction between ALA and FADS1 genotype on ischemic stroke incidence (P = 0.03). ALA was inversely associated with ischemic stroke only among TT genotype carriers (HR for quintile 5 vs. quintile 1 = 0.50; 95% CI: 0.27, 0.94; P-trend = 0.02). In this large cohort, we found some weak, but not convincing, evidence of effect modification by genetic variation in FADS1 on the associations between PUFA intakes and CVD risk. For the 11% of the population homozygous for the minor T-allele of rs174546 that associates with lower ∆5 FADS activity, high ALA intake and ALA-to-LA intake ratio may be preferable in the prevention of CVD and ischemic stroke.

Interleukin-6 gene polymorphisms, dietary fat intake, obesity and serum lipid concentrations in black and white South African women

This study investigated interactions between dietary fat intake and IL-6 polymorphisms on obesity and serum lipids in black and white South African (SA) women. Normal-weight and obese, black and white women underwent measurements of body composition, serum lipids and dietary fat intake, and were genotyped for the IL-6 -174 G>C, IVS3 +281 G>T and IVS4 +869 A>G polymorphisms. In black women the IVS4 +869 G allele was associated with greater adiposity, and with increasing dietary fat intake adiposity increased in the IVS3 +281 GT+GG and IVS4 +869 AA or AG genotypes. In white women, with increasing omega-3 (n-3) intake and decreasing n-6:n-3 ratio, body mass index (BMI) decreased in those with the -174 C allele, IVS3 +281 T allele and IVS4 +869 AG genotype. In the white women, those with the IVS3 +281 T allele had lower triglycerides. Further, with increasing n-3 polyunsaturated fatty acid (PUFA); triglyceride and total cholesterol:high-density lipoprotein cholesterol (T-C:HDL-C) ratio decreased in those with the -174 C allele. In black women, with increasing total fat intake, triglycerides and T-C:HDL-C ratio increased in those with the IVS4 +869 G allele. This study is the first to show that dietary fat intake modulates the relationship between the IL-6 -174 G>C, IVS3 +281 G>T and IVS4 +869 A>G polymorphisms on obesity and serum lipids in black and white SA women.

Genetic predisposition scores for dyslipidaemia influence plasma lipid concentrations at baseline, but not the changes after controlled intake of n-3 polyunsaturated fatty acids

Inconsistent effects of fish oil supplementation on plasma lipids may be influenced by genetic variation. We investigated 12 single nucleotide polymorphisms (SNPs) associated with dyslipidaemia in genome-wide association studies, in 310 participants randomised to treatment with placebo or 0.45, 0.9 and 1.8 g/day eicosapentaenoic acid (20:5n-3, EPA) and docosahexaenoic acid (22:6n-3, DHA) (1.51:1) in a 12-month parallel controlled trial. Effects of risk alleles were assessed as trait-specific genetic predisposition scores (GPS) and singly. GPS were positively associated with baseline concentrations of plasma total cholesterol, low-density-lipoprotein cholesterol and triglyceride (TG) and negatively with high-density-lipoprotein cholesterol. The TG-GPS was associated with 0.210 mmol/L higher TG per risk allele (P < 0.0001), but no effects of single TG SNPs were significant at baseline. After treatment with EPA and DHA, TG-GPS was associated with 0.023 mmol/L lower TG per risk allele (P = 0.72). No interactions between GPS and treatment were significant; however, FADS1 SNP rs174546 C/T interaction with treatment was a significant determinant of plasma TG concentration (P = 0.047, n = 267). Concentration differed between genotype groups after the 1.8 g/day dose (P = 0.026), decreasing by 3.5 (95 % CI -15.1 to 8.2) % in non-carriers of the risk T-allele (n = 30) and by 21.6 (95 % CI -32.1 to -11.2) % in carriers (n = 37), who showed a highly significant difference between treatments (P = 0.007). Carriers of the FADS1 rs174546 risk allele could benefit from a high intake of EPA and DHA in normalising plasma TG.

Present and future of genotype-based personalized nutrition

After the completion of the Human Genome Project, the era of providing personalized dietary advice based on an individual’s genetic profile seemed near. Since then more than a decade has passed and the pace of development has been slower than expected. Genotyping single nucleotide polymorphisms which may determine susceptibility to multifactorial diseases is cheaper and more accessible than it was ten years ago. However, few of them are supported by such solid scientific evidence which would justify their use for personalized dietary advice. The future of genotype-based personalized nutrition depends on whether a sufficient amount of gene–diet-disease interactions are identified and scientifically confirmed. Orv. Hetil., 2014, 155(20), 771–777.

Genetic Variants in the FADS Gene: Implications for Dietary Recommendations for Fatty Acid Intake

Unequivocally, genetic variants within the fatty acid desaturase (FADS) cluster are determinants of long chain polyunsaturated fatty acid (LC-PUFA) levels in circulation, cells and tissues. A recent series of papers have addressed these associations in the context of ancestry; evidence clearly supports that the associations are robust to ethnicity. However ∼80% of African Americans carry two copies of the alleles associated with increased levels of arachidonic acid, compared to only ∼45% of European Americans raising important questions of whether gene-PUFA interactions induced by a modern western diet are differentially driving the risk of diseases of inflammation in diverse populations, and are these interactions leading to health disparities. We highlight an important aspect thus far missing in the debate regarding dietary recommendations; we content that current evidence from genetics strongly suggest that an individual's, or at the very least the population from which an individual is sampled, genetic architecture must be factored into dietary recommendations currently in place.

Associations between variants of FADS genes and omega-3 and omega-6 milk fatty acids of Canadian Holstein cows

BACKGROUND

Fatty acid desaturase 1 (FADS1) and 2 (FADS2) genes code respectively for the enzymes delta-5 and delta-6 desaturases which are rate limiting enzymes in the synthesis of polyunsaturated omega-3 and omega-6 fatty acids (FAs). Omega-3 and-6 FAs as well as conjugated linoleic acid (CLA) are present in bovine milk and have demonstrated positive health effects in humans. Studies in humans have shown significant relationships between genetic variants in FADS1 and 2 genes with plasma and tissue concentrations of omega-3 and-6 FAs. The aim of this study was to evaluate the extent of sequence variations within these two genes in Canadian Holstein cows as well as the association between sequence variants and health promoting FAs in milk.

RESULTS

Thirty three SNPs were detected within the studied regions of genes including a synonymous mutation (FADS1-07, rs42187261, 306Tyr > Tyr) in exon 8 of FADS1, a non-synonymous mutation (FADS2-14, rs211580559, 294Ala > Val) within FADS2 exon 7, a splice site SNP (FADS2-05, rs211263660), a 3'UTR SNP (FADS2-23, rs109772589), and another 3'UTR SNP with an effect on a microRNA binding site within FADS2 gene (FADS2-19, rs210169303). Association analyses showed significant relations between three out of seven tested SNPs and several FAs. Significant associations (FDR P < 0.05) were recorded between FADS2-23 (rs109772589) and two omega-6 FAs (dihomogamma linolenic acid [C20:3n6] and arachidonic acid [C20:4n6]), FADS1-07 (rs42187261) and one omega-3 FA (eicosapentaenoic acid, C20:5n3) and tricosanoic acid (C23:0), and one intronic SNP, FADS1-01 (rs136261927) and C20:3n6.

CONCLUSION

Our study has demonstrated positive associations between three SNPs within FADS1 and FADS2 genes (a SNP within the 3'UTR, a synonymous SNP and an intronic SNP), with three milk PUFAs of Canadian Holstein cows thus suggesting possible involvement of synonymous and non-coding region variants in FA synthesis. These SNPs may serve as potential genetic markers in breeding programs to increase milk FAs that are of benefit to human health.

Erythrocyte membrane docosapentaenoic acid levels are associated with islet autoimmunity: the Diabetes Autoimmunity Study in the Young

AIMS/HYPOTHESES

We previously reported that lower n-3 fatty acid intake and levels in erythrocyte membranes were associated with increased risk of islet autoimmunity (IA) but not progression to type 1 diabetes in children at increased risk for diabetes. We hypothesise that specific n-3 fatty acids and genetic markers contribute synergistically to this increased risk of IA in the Diabetes Autoimmunity Study in the Young (DAISY).

METHODS

DAISY is following 2,547 children at increased risk for type 1 diabetes for the development of IA, defined as being positive for glutamic acid decarboxylase (GAD)65, IA-2 or insulin autoantibodies on two consecutive visits. Using a case-cohort design, erythrocyte membrane fatty acids and dietary intake were measured prospectively in 58 IA-positive children and 299 IA-negative children.

RESULTS

Lower membrane levels of the n-3 fatty acid, docosapentaenoic acid (DPA), were predictive of IA (HR 0.23; 95% CI 0.09, 0.55), while α-linolenic acid (ALA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were not, adjusting for HLA and diabetes family history. We examined whether the effect of dietary intake of the n-3 fatty acid ALA on IA risk was modified by fatty acid elongation and desaturation genes. Adjusting for HLA, diabetes family history, ethnicity, energy intake and questionnaire type, ALA intake was significantly more protective for IA in the presence of an increasing number of minor alleles at FADS1 rs174556 (pinteraction = 0.017), at FADS2 rs174570 (pinteraction = 0.016) and at FADS2 rs174583 (pinteraction = 0.045).

CONCLUSIONS/INTERPRETATION

The putative protective effect of n-3 fatty acids on IA may result from a complex interaction between intake and genetically controlled fatty acid desaturation.

Difference in effects of cigarette smoking or alcohol consumption on serum non-high-density lipoprotein cholesterol levels is related to mitochondrial DNA 5178 C/A polymorphism in middle-aged Japanese men: a cross-sectional study

BACKGROUND

Mitochondrial DNA 5178 cytosine/adenosine (Mt5178 C/A) polymorphism is associated with longevity in the Japanese. The purpose of this study is to investigate whether Mt5178 C/A polymorphism modifies the effects of habitual smoking or habitual drinking on serum non-high-density lipoprotein (non-HDL) cholesterol levels in middle-aged Japanese men.

METHODS

A total of 394 male subjects (age 53.9 ± 7.9 years; mean ± SD) were selected from among individuals visiting the hospital for regular medical check-ups. After Mt5178 C/A genotyping, a cross-sectional study assessing the joint effects of Mt5178 C/A polymorphism and cigarette smoking or alcohol drinking on serum non-HDL cholesterol levels was conducted. High levels of serum non-HDL cholesterol were defined as serum non-HDL cholesterol levels ≥160 mg/dl or ≥190 mg/dl.

RESULTS

For men with Mt5178A, cigarette smoking may increase serum non-HDL cholesterol levels (P for trend < 0.001), as well as the risk of high levels of non-HDL cholesterol (serum non-HDL cholesterol levels ≥160 mg/dl, P for trend < 0.001; serum non-HDL cholesterol levels ≥190 mg/dl, P for trend = 0.004). On the other hand, for men with Mt5178C, after adjusting for age and body mass index, alcohol consumption may decrease serum non-HDL cholesterol levels (P for trend = 0.043) and the risk of high levels of non-HDL cholesterol (serum non-HDL cholesterol level ≥160 mg/dl, P for trend = 0.005).

CONCLUSIONS

These gene-environment interactions on serum non-HDL cholesterol levels may contribute to the establishment of individualized prevention of the risk of high levels of serum non-HDL cholesterol.

Interaction of fatty acid genotype and diet on changes in colonic fatty acids in a Mediterranean diet intervention study

A Mediterranean diet increases intakes of n-3 and n-9 fatty acids and lowers intake of n-6 fatty acids. This can impact colon cancer risk as n-6 fatty acids are metabolized to proinflammatory eicosanoids. The purpose of this study was to evaluate interactions of polymorphisms in the fatty acid desaturase (FADS) genes, FADS1 and FADS2, and changes in diet on fatty acid concentrations in serum and colon. A total of 108 individuals at increased risk of colon cancer were randomized to either a Mediterranean or a Healthy Eating diet. Fatty acids were measured in both serum and colonic mucosa at baseline and after six months. Each individual was genotyped for four single-nucleotide polymorphisms in the FADS gene cluster. Linear regression was used to evaluate the effects of diet, genotype, and the diet by genotype interaction on fatty acid concentrations in serum and colon. Genetic variation in the FADS genes was strongly associated with baseline serum arachidonic acid (n-6) but serum eicosapentaenoic acid (n-3) and colonic fatty acid concentrations were not significantly associated with genotype. After intervention, there was a significant diet by genotype interaction for arachidonic acid concentrations in colon. Subjects who had all major alleles for FADS1/2 and were following a Mediterranean diet had 16% lower arachidonic acid concentrations in the colon after six months of intervention than subjects following the Healthy Eating diet. These results indicate that FADS genotype could modify the effects of changes in dietary fat intakes on arachidonic acid concentrations in the colon.

The relationship between dietary fatty acids and inflammatory genes on the obese phenotype and serum lipids

Obesity, a chronic low-grade inflammatory condition is associated with the development of many comorbidities including dyslipidemia. This review examines interactions between single nucleotide polymorphisms (SNP) in the inflammatory genes tumor necrosis alpha (TNFA) and interleukin-6 (IL-6) and dietary fatty acids, and their relationship with obesity and serum lipid levels. In summary, dietary fatty acids, in particular saturated fatty acids and the omega-3 and omega-6 polyunsaturated fatty acids, impact the expression of the cytokine genes TNFA and IL-6, and alter TNFα and IL-6 production. In addition, sequence variants in these genes have also been shown to alter their gene expression and plasma levels, and are associated with obesity, measures of adiposity and serum lipid concentrations. When interactions between dietary fatty acids and TNFA and IL-6 SNPs on obesity and serum lipid were analyzed, both the quantity and quality of dietary fatty acids modulated the relationship between TNFA and IL-6 SNPs on obesity and serum lipid profiles, thereby impacting the association between phenotype and genotype. Researching these diet–gene interactions more extensively, and understanding the role of ethnicity as a confounder in these relationships, may contribute to a better understanding of the inter-individual variability in the obese phenotype.

Genetic variation in FADS genes and plasma cholesterol levels in 2-year-old infants: KOALA Birth Cohort Study

Objective

Single nucleotide polymorphisms (SNPs) in genes involved in fatty acid metabolism (FADS1 FADS2 gene cluster) are associated with plasma lipid levels. We aimed to investigate whether these associations are already present early in life and compare the relative contribution of FADS SNPs vs traditional (non-genetic) factors as determinants of plasma lipid levels.

Methods

Information on infants’ plasma total cholesterol levels, genotypes of five FADS SNPs (rs174545, rs174546, rs174556, rs174561, and rs3834458), anthropometric data, maternal characteristics, and breastfeeding history was available for 521 2-year-old children from the KOALA Birth Cohort Study. For 295 of these 521 children, plasma HDLc and non-HDLc levels were also known. Multivariable linear regression analysis was used to study the associations of genetic and non-genetic determinants with cholesterol levels.

Results

All FADS SNPs were significantly associated with total cholesterol levels. Heterozygous and homozygous for the minor allele children had about 4% and 8% lower total cholesterol levels than major allele homozygotes. In addition, homozygous for the minor allele children had about 7% lower HDLc levels. This difference reached significance for the SNPs rs174546 and rs3834458. The associations went in the same direction for non-HDLc, but statistical significance was not reached. The percentage of total variance of total cholesterol levels explained by FADS SNPs was relatively low (lower than 3%) but of the same order as that explained by gender and the non-genetic determinants together.

Conclusions

FADS SNPs are associated with plasma total cholesterol and HDLc levels in preschool children. This brings a new piece of evidence to explain how blood lipid levels may track from childhood to adulthood. Moreover, the finding that these SNPs explain a similar amount of variance in total cholesterol levels as the non-genetic determinants studied reveals the potential importance of investigating the effects of genetic variations in early life.

Identification and MS-assisted interpretation of genetically influenced NMR signals in human plasma

Nuclear magnetic resonance spectroscopy (NMR) provides robust readouts of many metabolic parameters in one experiment. However, identification of clinically relevant markers in (1)H NMR spectra is a major challenge. Association of NMR-derived quantities with genetic variants can uncover biologically relevant metabolic traits. Using NMR data of plasma samples from 1,757 individuals from the KORA study together with 655,658 genetic variants, we show that ratios between NMR intensities at two chemical shift positions can provide informative and robust biomarkers. We report seven loci of genetic association with NMR-derived traits (APOA1, CETP, CPS1, GCKR, FADS1, LIPC, PYROXD2) and characterize these traits biochemically using mass spectrometry. These ratios may now be used in clinical studies.

Interaction between a common variant in FADS1 and erythrocyte polyunsaturated fatty acids on lipid profile in Chinese Hans

Little is known about the associations of FADS1 genetic variants with circulating levels of PUFA and lipids in Asian populations who have a different dietary pattern and dyslipidemia prevalence compared with Western populations. In a population-based sample of 3,210 unrelated Han Chinese living in Beijing and Shanghai, we examined a FADS1 genetic variant, rs174550, in relation to blood PUFA and lipid levels. C-allele of rs174550 was significantly associated with levels of erythrocyte PUFAs in upstream and downstream pathways of delta-5 desaturase (D5D) (P ≤ 0.003). Moreover, rs174550 C-allele was associated with a lower HDL cholesterol level (P = 0.02) in total population and a higher triglyceride level (P = 0.0002) in Beijing residents. Interestingly, erythrocyte levels of 18:2n-6 and 18:3n-3 modified the effect of rs174550 on HDL cholesterol level: stronger associations between rs174550 C-allele and lower HDL cholesterol levels were exhibited when erythrocyte 18:2n-6 or 18:3n-3 level was low (P for interaction = 0.02 and 0.03, respectively). These data suggested that FADS1 genetic variant was associated with circulating PUFA and lipid levels and that its effect on HDL cholesterol might depend on PUFA status in the Han Chinese population.