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  1. All, I'm usually reluctant to post studies that try to associate single nucleotide polymorphisms (SNPs) with health or longevity outcomes. There are several reasons to be skeptical of such gene studies, including: They often fail to replicate across different populations The effects of individual SNP variations are often quite small - since there are usually many genes and polymorphisms that contribute to any important health/longevity outcome Often it's not even clear from the study what the specific allele variation(s) the authors are evaluating You often can't even find out what variant of an allele you have - since only some of us have our own genetic data and even that is only partial coverage through 23andMe. There is nothing you can do about it anyway - your genes are your genes. These polymorphisms and their effects often have nothing to do with CR. But this new meta-analysis [1] posted by Al Pater (thanks Al!) seems to suffer from none of these shortcomings. It focuses on a SNP in the FoxO3 gene (rs2802292) which has been previously associated with longevity - is it overrepresented in centenarians [2], as discussed here, and summarized as: [T]he odds ratio for reaching 100 years of age for rs2802292(G;G) vs (T;T) carriers was 2.75 (p = 0.00009; adjusted p = 0.00135). One's odds of living to 100 with one copy of 'G' for rs2802292 (i.e. G:T), appears to be about 1.5-2 times greater than people with T:T. Those results were encouraging, but didn't address causality, and was limited to a homogeneous population of men. Plus it only seemed relevant for people without other 'gotchas' (genetic or otherwise) that might kill them off long before reaching 100. What about the rest of us mortals, who may not be destined to live that long? Does having copies of the 'G' allele for rs2802292 do the rest of us any good on the way to extreme longevity? Apparently - Yes! Study [1] followed three pretty large groups of Americans with Japanese (N ≈ 3600), Caucasian (N ≈ 1600), or African (N ≈ 1000) ancestory for 17 years to assess the association between SNP rs2802292 status and mortality. Interestingly, the frequency of being a lucky 'G' Allele Carrier (GAC) for this SNP varied between the three populations - 47% of Japanese, 58% of Caucasian and 92% of African ancestry folks were GACs. Across all three populations, being a GAC was associated with a 10% reduction in all-cause mortality over the 17 year follow-up, with virtually all of the benefit resulting from a 26% reduction in heart disease mortality. Here is the most important figure from the free full text: As you can see the effect was quite consistent across the three populations. The difference in the confidence interval for the three groups was a result of the different population sizes. The cool thing is that those of us with 23andMe data can find out our status for SNP rs2802292. Simply log in to 23andMe and follow this link. I'm fortunate to be in the ~60% of caucasian people who is a 'G' carrier for this allele (I've got one copy). But for anyone who isn't lucky enough to be a GAC for this allele, there is still hope. Why? Because FoxO3 gene activity is something we know quite a bit about, including ways of boosting its activity, like the G allele for rs2802292 apparently does. Curiously, cider vinegar appears to upregulate DAF-16, the C. Elegans equivalent of FoxO3, which in turn resulted in the worms living 25% longer, as discussed here. So maybe cider vinegar is worth including in one's diet. I do. But even more relevant, we know that both CR and cold exposure increase FoxO3 gene expression largely by upregulating SIRT1, as discussed recently here. So everybody wins! --Dean ------------------ [1] The FoxO3 gene and cause-specific mortality. Willcox BJ, Tranah GJ, Chen R, Morris BJ, Masaki KH, He Q, Willcox DC, Allsopp RC, Moisyadi S, Poon LW, Rodriguez B, Newman AB, Harris TB, Cummings SR, Liu Y, Parimi N, Evans DS, Davy P, Gerschenson M, Donlon TA. Aging Cell. 2016 Apr 13. doi: 10.1111/acel.12452. [Epub ahead of print] Free Article http://onlinelibrary.wiley.com/doi/10.1111/acel.12452/full http://onlinelibrary.wiley.com/doi/10.1111/acel.12452/pdf Abstract The G allele of the FOXO3 single nucleotide polymorphism (SNP) rs2802292 exhibits a consistently replicated genetic association with longevity in multiple populations worldwide. The aims of this study were to quantify the mortality risk for the longevity-associated genotype and to discover the particular cause(s) of death associated with this allele in older Americans of diverse ancestry. It involved a 17-year prospective cohort study of 3584 older American men of Japanese ancestry from the Honolulu Heart Program cohort, followed by a 17-year prospective replication study of 1595 white and 1056 black elderly individuals from the Health Aging and Body Composition cohort. The relation between FOXO3 genotype and cause-specific mortality was ascertained for major causes of death including coronary heart disease (CHD), cancer, and stroke. Age-adjusted and multivariable Cox proportional hazards models were used to compute hazard ratios (HRs) for all-cause and cause-specific mortality. We found G allele carriers had a combined (Japanese, white, and black populations) risk reduction of 10% for total (all-cause) mortality (HR = 0.90; 95% CI, 0.84-0.95; P = 0.001). This effect size was consistent across populations and mostly contributed by 26% lower risk for CHD death (HR = 0.74; 95% CI, 0.64-0.86; P = 0.00004). No other causes of death made a significant contribution to the survival advantage for G allele carriers. In conclusion, at older age, there is a large risk reduction in mortality for G allele carriers, mostly due to lower CHD mortality. The findings support further research on FOXO3 and FoxO3 protein as potential targets for therapeutic intervention in aging-related diseases, particularly cardiovascular disease. KEYWORDS: FOXO3; heart disease; longevity; mortality PMID: 27071935 -------------- [2] Proc Natl Acad Sci U S A. 2008 Sep 16;105(37):13987-92. doi: 10.1073/pnas.0801030105. Epub 2008 Sep 2. FOXO3A genotype is strongly associated with human longevity. Willcox BJ(1), Donlon TA, He Q, Chen R, Grove JS, Yano K, Masaki KH, Willcox DC, Rodriguez B, Curb JD. Author information: (1)Pacific Health Research Institute, 846 South Hotel Street, Honolulu, HI 96813, USA. bjwillcox@phrihawaii.org Human longevity is a complex phenotype with a significant familial component, yet little is known about its genetic antecedents. Increasing evidence from animal models suggests that the insulin/IGF-1 signaling (IIS) pathway is an important, evolutionarily conserved biological pathway that influences aging and longevity. However, to date human data have been scarce. Studies have been hampered by small sample sizes, lack of precise phenotyping, and population stratification, among other challenges. Therefore, to more precisely assess potential genetic contributions to human longevity from genes linked to IIS signaling, we chose a large, homogeneous, long-lived population of men well-characterized for aging phenotypes, and we performed a nested-case control study of 5 candidate longevity genes. Genetic variation within the FOXO3A gene was strongly associated with human longevity. The OR for homozygous minor vs. homozygous major alleles between the cases and controls was 2.75 (P = 0.00009; adjusted P = 0.00135). Long-lived men also presented several additional phenotypes linked to healthy aging, including lower prevalence of cancer and cardiovascular disease, better self-reported health, and high physical and cognitive function, despite significantly older ages than controls. Several of these aging phenotypes were associated with FOXO3A genotype. Long-lived men also exhibited several biological markers indicative of greater insulin sensitivity and this was associated with homozygosity for the FOXO3A GG genotype. Further exploration of the FOXO3A gene, human longevity and other aging phenotypes is warranted in other populations. PMCID: PMC2544566 PMID: 18765803
  2. In his weekly post of new CR Science studies, James Cain (thanks James!) posted [1], another in the series of papers about results from the CALERIE study of six months of CR in modestly overweight humans. In this analysis they divided 24 people into three groups of 8 people each and followed them for six months: control diet (control group) 25% Calorie Restriction (CR group) 12.5% CR + enough exercise to equal a 25% calorie deficit (CREX group). Both intervention groups lost about the same amount of bodyweight (~11%). They took subcutaneous fat cell biopsies from the three groups at baseline and at six months, and subjected them to gene expression analysis. Here are the major highlights from the full text: Despite comparable transcriptional and clinical response in energy metabolism, we showed that CR vastly outweighed CREX in the total number of differentially regulated genes (88 vs 39) and pathways (28 vs 6). This suggests that calorie restriction is probably eliciting molecular changes beyond adaptations to energy deficit per se. <snip> CR induced a ... 2.1-fold (p < .05) increase in the mRNA expression of ... CGI-85 [a regulator of epigenetic histone modification - DP], ...whereas CREX and Control were without effect. <snip> [W]e observed a distinct effect of CR on downregulating the chemokine signaling-related pathways. [From this description of the chemokine signalling pathways: "chemokines are a critical component of basal leukocyte trafficking essential for immune system architecture and development, and immune surveillance." - DP] <snip> Together, our data suggest that CR regulates the overall transcriptional function, and this does not appear to be a primary response to energy deficit per se but rather a distinct effect of calorie restriction. Genomic effects may also be the key regulator of the aging process. Pioneering work from the laboratories of Weindruch and Spindler showed that most differential gene expression induced by aging in rodents was at least partly or completely reversed by calorie restriction (42,43). The Spindler group further showed that shifting mice from long-term calorie restricted to control diet reversed 90% of the transcriptional changes induced by calorie restriction and returned the animals to an aging rate similar to the controls (44), implicating a causal relationship between calorie restriction, gene expression, and aging. <snip> Available literature to date largely agrees that calorie restriction and exercise training overlap in a wide range of health benefits from weight loss to protection against some age-related diseases (55). Extension of maximal life span, however, remains as a unique feature of calorie restriction that so far cannot be replicated by any form of exercise training (56,57). <snip> Finally, given the enormous challenge (and an almost impossible task) of maintaining drastic lifestyle changes such as life-long calorie restriction, identifying specific molecular targets will be critical for the development of calorie restriction mimetics (59). Its pretty annoying that authors feel obligated to dismiss the possibility of people practicing long-term CR as being "almost impossible". Luigi Fontana wasn't an author on this one (thankfully), and perhaps if he had been the paper wouldn't have ended on such a low note. But despite this disempowering and dismissive ending, it was one of the most interesting papers I've seen coming out of the CALERIE study, suggesting that CR in humans (whether induced by straight calorie reduction or CR + exercise) does have some pretty fundamental effects on gene expression in fat cells. In addition, it found that CR-alone has a more profound and widespread impact on gene expression than more modest CR "topped off" with extra exercise (the CREX group), at least in the relatively short term (6 months) in this (relatively overweight) cohort. In particular, they found that CR (but not CR+EX) downregulates certain aspects of chemokine pathways related to immune system function (good or bad, who knows, but our immune systems seem pretty competent...), and changes the expression of genes involved in epigenetic regulation (master genes regulating expression of other genes) - which is increasingly thought to be important in the aging process. These results complement and extend similar findings in skeletal muscle cells from this same cohort [2] and some of us long-term CR practitioners [3]. Interestingly, from [2], it seems that CR-alone and CR+Exercise had much more similar effects on muscle cell gene expression as compared to this study of gene expression in fat cells, where the effects of CR-alone differed markedly from CR+exercise. --Dean ------------ [1] J Gerontol A Biol Sci Med Sci. 2015 Oct 20. pii: glv194. [Epub ahead of print] Six-month Calorie Restriction in Overweight Individuals Elicits Transcriptomic Response in Subcutaneous Adipose Tissue That is Distinct From Effects of Energy Deficit. Lam YY1, Ghosh S2, Civitarese AE3, Ravussin E4. Abstract Calorie restriction confers health benefits distinct from energy deficit by exercise. We characterized the adipose-transcriptome to investigate the molecular basis of the differential phenotypic responses. Abdominal subcutaneous fat was collected from 24 overweight participants randomized in three groups (N = 8/group): weight maintenance (control), 25% energy deficit by calorie restriction alone (CR), and 25% energy deficit by calorie restriction with structured exercise (CREX). Within each group, gene expression was compared between 6 months and baseline with cutoffs at nominal p ≤ .01 and absolute fold-change ≥ 1.5. Gene-set enrichment analysis (false discovery rate < 5%) was used to identify significantly regulated biological pathways. CR and CREX elicited similar overall clinical response to energy deficit and a comparable reduction in gene transcription specific to oxidative phosphorylation and proteasome function. CR vastly outweighed CREX in the number of differentially regulated genes (88 vs 39) and pathways (28 vs 6). CR specifically downregulated the chemokine signaling-related pathways. Among the CR-regulated genes, 27 functioned as transcription/translation regulators (eg, mRNA processing or transcription/translation initiation), whereas CREX regulated only one gene in this category. Our data suggest that CR has a broader effect on the transcriptome compared with CREX which may mediate its specific impact on delaying primary aging. PMID: 26486851 ----------- [2] PLoS Med. 2007 Mar;4(3):e76. Calorie restriction increases muscle mitochondrial biogenesis in healthy humans. Civitarese AE(1), Carling S, Heilbronn LK, Hulver MH, Ukropcova B, Deutsch WA, Smith SR, Ravussin E; CALERIE Pennington Team. BACKGROUND: Caloric restriction without malnutrition extends life span in a range of organisms including insects and mammals and lowers free radical production by the mitochondria. However, the mechanism responsible for this adaptation are poorly understood. METHODS AND FINDINGS: The current study was undertaken to examine muscle mitochondrial bioenergetics in response to caloric restriction alone or in combination with exercise in 36 young (36.8 +/- 1.0 y), overweight (body mass index, 27.8 +/- 0.7 kg/m(2)) individuals randomized into one of three groups for a 6-mo intervention: Control, 100% of energy requirements; CR, 25% caloric restriction; and CREX, caloric restriction with exercise (CREX), 12.5% CR + 12.5% increased energy expenditure (EE). In the controls, 24-h EE was unchanged, but in CR and CREX it was significantly reduced from baseline even after adjustment for the loss of metabolic mass (CR, -135 +/- 42 kcal/d, p = 0.002 and CREX, -117 +/- 52 kcal/d, p = 0.008). Participants in the CR and CREX groups had increased expression of genes encoding proteins involved in mitochondrial function such as PPARGC1A, TFAM, eNOS, SIRT1, and PARL (all, p < 0.05). In parallel, mitochondrial DNA content increased by 35% +/- 5% in the CR group (p = 0.005) and 21% +/- 4% in the CREX group (p < 0.004), with no change in the control group (2% +/- 2%). However, the activity of key mitochondrial enzymes of the TCA (tricarboxylic acid) cycle (citrate synthase), beta-oxidation (beta-hydroxyacyl-CoA dehydrogenase), and electron transport chain (cytochrome C oxidase II) was unchanged. DNA damage was reduced from baseline in the CR (-0.56 +/- 0.11 arbitrary units, p = 0.003) and CREX (-0.45 +/- 0.12 arbitrary units, p = 0.011), but not in the controls. In primary cultures of human myotubes, a nitric oxide donor (mimicking eNOS signaling) induced mitochondrial biogenesis but failed to induce SIRT1 protein expression, suggesting that additional factors may regulate SIRT1 content during CR. CONCLUSIONS: The observed increase in muscle mitochondrial DNA in association with a decrease in whole body oxygen consumption and DNA damage suggests that caloric restriction improves mitochondrial function in young non-obese adults. PMID: 17341128 -------------- [3] Aging Cell. 2013 Aug;12(4):645-51. doi: 10.1111/acel.12088. Epub 2013 Jun 5. Calorie restriction in humans inhibits the PI3K/AKT pathway and induces a younger transcription profile. Mercken EM(1), Crosby SD, Lamming DW, JeBailey L, Krzysik-Walker S, Villareal DT, Capri M, Franceschi C, Zhang Y, Becker K, Sabatini DM, de Cabo R, Fontana L. Caloric restriction (CR) and down-regulation of the insulin/IGF pathway are the most robust interventions known to increase longevity in lower organisms. However, little is known about the molecular adaptations induced by CR in humans. Here, we report that long-term CR in humans inhibits the IGF-1/insulin pathway in skeletal muscle, a key metabolic tissue. We also demonstrate that CR induces dramatic changes of the skeletal muscle transcriptional profile that resemble those of younger individuals. Finally, in both rats and humans, CR evoked similar responses in the transcriptional profiles of skeletal muscle. This common signature consisted of three key pathways typically associated with longevity: IGF-1/insulin signaling, mitochondrial biogenesis, and inflammation. Furthermore, our data identify promising pathways for therapeutic targets to combat age-related diseases and promote health in humans. PMID: 23601134
  3. Dean Pomerleau

    Genetics of Obesity

    There is an new study on the link between genetics and obesity reported on in this popular press article: http://www.huffingtonpost.com/entry/obesity-gene-discovery-could-forever-change-weight-loss_55d4f994e4b0ab468d9fc0f4 Study [1] is the (rather technical) abstract for the paper associated with the story. I'll do my best to summarize the background and the findings of this study, which I found really interesting. First a little background. It has been known for a while that a particular gene on chromosome 16 named FTO has many (over 200) SNPs (single nucleotide polymorphisms - i.e. common variations in particular base pairs along this gene), several of which appear to be associated with obesity. Here are two older studies [2][3] that address this linkage. Study [2] focused on SNP rs9939609. It found that people who carry one (or especially two) copies of the 'obese' allele ('A') for this SNP were significantly more likely to be obese than those who carry the 'lean' variant ('T'). Study [3] found the same thing for three other FTO SNPs, rs1421085, rs17817449 and rs8043757. It found that people with the 'obese' variants for these three SNPs ('C', 'G' and 'T', respectively) were about 2.5 times more likely to be obese than those who had the lean variants for these three SNPs ('T', 'T', 'A', respectively). The newest study [1], focused on the first of the three SNPs from [3], namely SNP rs1421085, and did something really cool and cutting edge. They took fat cells from mice and humans and used the recently-developed CRISPR gene editing technique to change this particular SNP from the 'obese' variant ('C') to the 'lean' variant ('T'), and then observed what happened to the cells. What they found was that the fat cells converted from being thermogenically active, 'beige' fat cells (i.e. like brown fat cells) to 'white' fat cells that are much more efficient at storing fat, rather than burning it. This can be spun as a nice mechanistic story to explain why at least this SNP is associated with obesity. People who have 'C' for rs1421085 produce more white fat cells, making them more efficient at storing fat - i.e. they have a more 'thrifty' genotype and will therefore (presumably) store more fat for a given calorie intake. Now comes the interesting citizen science part. Data on all four of obesity-related SNPs mentioned above are available to subscribers of 23andMe. Simply log in, then go to this page: https://www.23andme.com/you/explorer/gene/?gene_name=FTO to get a list of all 200+ SNPs from the FTO gene that 23andMe sequences, and search on the page for these four SNPs. Here are my results: rs9939609 TT (lean variant = T) rs1421085 TT (lean variant = T) rs17817449 TT (lean variant = T) rs8043757 AA (lean variant = A) As you can see, I've inherited two copies (one from each of my parents) of the 'lean' allele for each of these four SNPs. So it is no wonder that unintended weight gain has never been an problem for me - at least according to these SNPs I have the antithesis of the 'thrifty genotype'. I'm curious what other CRONies who are also subscribers to 23andMe have for these SNPs, and whether they consider themselves to have a 'thrifty genotype' (easily gain weight) or not. I also wonder whether long-term success on a CR lifestyle is in any way correlated with the values for these SNPs. There is some indication [4] that some of the FTO SNPs (including rs9939609) have an effect on energy intake and preference for energy dense (i.e. high fat) foods, and from [2] we saw that people with the 'obese' allele for rs9939609 and who eat a high-fat, low-carb diet have a higher BMI, which could discourage people trying to practice CR in order to lose weight. Conversely, having a 'thrifty genotype' might make it easier to maintain a low calorie intake without becoming terribly skinny, which can sometimes result in social pressure to eat more to avoid looking like a concentration camp victim. :) Anyway, I've probably grossly oversimplified the science, but I found it fascinating and would be interested to hear what other 23andMe subscribers have for these alleles. --Dean ------------------------------- [1] N Engl J Med. 2015 Aug 19. [Epub ahead of print] FTO Obesity Variant Circuitry and Adipocyte Browning in Humans. Claussnitzer M(1), Dankel SN, Kim KH, Quon G, Meuleman W, Haugen C, Glunk V, Sousa IS, Beaudry JL, Puviindran V, Abdennur NA, Liu J, Svensson PA, Hsu YH, Drucker DJ, Mellgren G, Hui CC, Hauner H, Kellis M. Background Genomewide association studies can be used to identify disease-relevant genomic regions, but interpretation of the data is challenging. The FTO region harbors the strongest genetic association with obesity, yet the mechanistic basis of this association remains elusive. Methods We examined epigenomic data, allelic activity, motif conservation, regulator expression, and gene coexpression patterns, with the aim of dissecting the regulatory circuitry and mechanistic basis of the association between the FTO region and obesity. We validated our predictions with the use of directed perturbations in samples from patients and from mice and with endogenous CRISPR-Cas9 genome editing in samples from patients. Results Our data indicate that the FTO allele associated with obesity represses mitochondrial thermogenesis in adipocyte precursor cells in a tissue-autonomous manner. The rs1421085 T-to-C single-nucleotide variant disrupts a conserved motif for the ARID5B repressor, which leads to derepression of a potent preadipocyte enhancer and a doubling of IRX3 and IRX5 expression during early adipocyte differentiation. This results in a cell-autonomous developmental shift from energy-dissipating beige (brite) adipocytes to energy-storing white adipocytes, with a reduction in mitochondrial thermogenesis by a factor of 5, as well as an increase in lipid storage. Inhibition of Irx3 in adipose tissue in mice reduced body weight and increased energy dissipation without a change in physical activity or appetite. Knockdown of IRX3 or IRX5 in primary adipocytes from participants with the risk allele restored thermogenesis, increasing it by a factor of 7, and overexpression of these genes had the opposite effect in adipocytes from nonrisk-allele carriers. Repair of the ARID5B motif by CRISPR-Cas9 editing of rs1421085 in primary adipocytes from a patient with the risk allele restored IRX3 and IRX5 repression, activated browning expression programs, and restored thermogenesis, increasing it by a factor of 7. Conclusions Our results point to a pathway for adipocyte thermogenesis regulation involving ARID5B, rs1421085, IRX3, and IRX5, which, when manipulated, had pronounced pro-obesity and anti-obesity effects. (Funded by the German Research Center for Environmental Health and others.). PMID: 26287746 --------------- [2] Br J Nutr. 2012 Nov 28;108(10):1859-65. doi: 10.1017/S0007114511007410. Epub 2012 Jan 23. Association of the fat mass and obesity-associated (FTO) gene variant (rs9939609) with dietary intake in the Finnish Diabetes Prevention Study. Lappalainen T(1), Lindström J, Paananen J, Eriksson JG, Karhunen L, Tuomilehto J, Uusitupa M. A cluster of variants in the fat mass and obesity-associated (FTO) gene are associated with the common form of obesity. Well-documented dietary data are required for identifying how the genetic risk can be modified by dietary factors. The objective of the present study was to investigate the associations between the FTO risk allele (rs9939609) and dietary intake, and to evaluate how dietary intake affects the association between FTO and BMI in the Finnish Diabetes Prevention Study during a mean follow-up of 3·2 years. A total of 479 (BMI >25 kg/m2) men and women were genotyped for rs9939609. The participants completed a 3 d food record at baseline and before every annual study visit. The average intakes at baseline and during the years 1, 2 and 3 were calculated. At baseline, the FTO variant rs9939609 was not associated with the mean values of total energy intake, macronutrients or fibre. At baseline, a higher BMI by the FTO risk genotype was detected especially in those who reported a diet high in fat with mean BMI of 30·6 (sd 4·1), 31·3 (sd 4·6) and 34·5 (sd 6·2) kg/m2 for TT, TA and AA carriers, respectively (P =0·005). Higher BMI was also observed in those who had a diet low in carbohydrates (P =0·028) and fibre (P =0·015). However, in the analyses adjusted for total energy intake, age and sex, significant interactions between FTO and dietary intakes were not found. These findings suggest that the association between the FTO genotype and obesity is influenced by the components of dietary intake, and the current dietary recommendations are particularly beneficial for those who are genetically susceptible for obesity. PMID: 22265018 ----------------------- [3] Gene. 2015 Mar 1;558(1):75-81. doi: 10.1016/j.gene.2014.12.050. Epub 2014 Dec 24. Common variations in the FTO gene and obesity in Thais: a family-based study. Chuenta W(1), Phonrat B(2), Tungtrongchitr A(3), Limwongse C(4), Chongviriyaphan N(5), Santiprabhob J(6), Tungtrongchitr R(7). Several studies have revealed the association between single nucleotide polymorphisms (SNPs) in the first intron of fat mass and obesity-associated (FTO) gene and obesity. To date, more than 100 SNPs in the FTO gene have been identified in various populations. Nevertheless, this association has not yet been confirmed in Thai populations. The aim of this study was to investigate whether FTO variants are associated with obesity in Thais. We analyzed ten variants in the FTO gene (rs9939609, rs9926289, rs8050136, rs9930501, rs9930506, rs9940646, rs9940128, rs1421085, rs17817449, and rs8043757) in 12 families (83 persons); composed of 12 proband cases and 71 associated family members. All participants were genotyped using polymerase chain reaction (PCR) method and DNA sequencing assay. We found significant associations between three SNPs located in the first intron of FTO gene (rs1421085, rs17817449, and rs8043757) and obesity. The odds ratios were 2.82 (95% CI, 1.16-6.90, p=0.02) for rs1421085 and rs17817449, and 3.15 (95% CI, 1.28-7.76, p=0.01) for rs8043757. Strong linkage disequilibrium among ten SNPs was observed (D'>0.8). Haplotype analysis (combination of rs1421085 (T/C), rs17817449 (T/G), and rs8043757 (A/T)) showed that the CGT haplotype is associated with an increased risk of obesity (OR, 2.42; 95% CI, 1.18-4.97; p=0.018) when compared to the reference haplotype (TTA). The SNPs rs1421085, rs17817449 and rs8043757 in the first intron of the FTO gene are associated with increasing risk of obesity in Thais. Copyright © 2014 Elsevier B.V. All rights reserved. PMID: 25542809 [PubMed - indexed for MEDLINE] ------------------ [4] N Engl J Med. 2008 Dec 11;359(24):2558-66. doi: 10.1056/NEJMoa0803839. An obesity-associated FTO gene variant and increased energy intake in children. Cecil JE(1), Tavendale R, Watt P, Hetherington MM, Palmer CN. Author information: (1)Bute Medical School, University of St Andrews, St Andrews, United Kingdom. Comment in N Engl J Med. 2009 Apr 9;360(15):1571-2; author reply 1572. N Engl J Med. 2008 Dec 11;359(24):2603-4. BACKGROUND: Variation in the fat mass and obesity-associated (FTO) gene has provided the most robust associations with common obesity to date. However, the role of FTO variants in modulating specific components of energy balance is unknown. METHODS: We studied 2726 Scottish children, 4 to 10 years of age, who underwent genotyping for FTO variant rs9939609 and were measured for height and weight. A subsample of 97 children was examined for possible association of the FTO variant with adiposity, energy expenditure, and food intake. RESULTS: In the total study group and the subsample, the A allele of rs9939609 was associated with increased weight (P=0.003 and P=0.049, respectively) and body-mass index (P=0.003 and P=0.03, respectively). In the intensively phenotyped subsample, the A allele was also associated with increased fat mass (P=0.01) but not with lean mass. Although total and resting energy expenditures were increased in children with the A allele (P=0.009 and P=0.03, respectively), resting energy expenditure was identical to that predicted for the age and weight of the child, indicating that there is no defect in metabolic adaptation to obesity in persons bearing the risk-associated allele. The A allele was associated with increased energy intake (P=0.006) independently of body weight. In contrast, the weight of food ingested by children who had the allele was similar to that in children who did not have the allele (P=0.82). CONCLUSIONS: The FTO variant that confers a predisposition to obesity does not appear to be involved in the regulation of energy expenditure but may have a role in the control of food intake and food choice, suggesting a link to a hyperphagic phenotype or a preference for energy-dense foods. 2008 Massachusetts Medical Society PMID: 19073975
  4. In my exploration of nutrigenomics, I came across this interesting recent study [1] that looked at the interaction between a particular gene polymorphism (rs4977574 - available on 23andMe) and cardiovascular disease (CVD), as mediated by consumption of either vegetables or wine. The researchers followed 24,000 people for 15 years, during which time about 3000 of them developed cardiovascular disease. So it was a pretty big cohort, with lots of people experiencing the outcome in question - cardiovascular disease. Across the entire population, eating more veggies and drinking more wine resulted in less CVD - not too surprising given previous research on the health benefits of these foods. Things got more interesting when the researchers looked at polymorphisms of SNP rs4977574. Having one or two of the risk alleles (G worse than A) for this SNP on chromosome 9 has been previously shown to be associated with an increased risk of CVD [2]. For example, study [3] found for every G allele one carries, one has about a 13% increased risk of CVD. Study [2] was similar - in the 20-25% of the population that carry two G alleles for this SNP, risk of CVD was increased 30-40% relative to people with AA for rs4977574. This new study [1] found something very similar - for each additional G allele at rs4977574, people were 16% more likely to develop CVD. And these polymorphisms are quite common, ~30% of the study population were AA for rs4977574, 50% were AG, and 20% were GG. But things got really interesting when they looked at how vegetable and wine consumption influenced with the link between this polymorphism and CVD. For people with two 'normal' alleles for rs4977574 (AA), increasing vegetable intake was associated with lower CVD, just like in the population as a whole - no surprise. But for people with either one or two G's for rs4977574, higher vegetable intake didn't help! In other words, compared with high consumers of vegetables who carried two A's for rs4977574 (the reference group), people with AG for rs4977574 were 20-30% more likely to develop CVD, and people with GG for rs4977574 were 40-50% more likely to develop CVD, regardless of how many vegetables they ate! The opposite was true for wine. Wine didn't help reduce risk of CVD in AA carriers for rs4977574, but it did reduce risk in AG and GG carriers, by ~30% and ~40% respectively! In fact, drinking wine appeared to nearly entirely counteract the baseline increased risk of CVD in AG and GG carriers, relative to AA carriers. Here is the relevant table of results from the paper for those interested in the precise details: In summary, this study suggests that if you have one or (especially) two G alleles for rs4977574, you are at higher risk for cardiovascular disease, and that consuming wine, but not vegetables, can help lower your risk. FYI, 23andMe shows I've got one G allele for rs4977574 - which is a bummer since I love veggies and don't drink alcohol. :( Of course its only one study, and one gene locus, so the results should be taken with a grain of salt. I don't plan to eat fewer veggies or take up drinking as a result of this study, particularly since alcoholism runs in my family. I figure my good cholesterol numbers and healthy diet/lifestyle make it unlikely I'll die of CVD anyway. But it seems like another interesting example how genes and diet/lifestyle can interact to influence health in significant and sometimes surprising ways. --Dean ------------------------------------------- [1] BMC Med Genet. 2014 Dec 31;15(1):1220. [Epub ahead of print] The chromosome 9p21 variant interacts with vegetable and wine intake to influence the risk of cardiovascular disease: a population based cohort study. Hindy G, Ericson U, Hamrefors V, Drake I, Wirfält E, Melander O, Orho-Melander M. Full Text: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4331503/pdf/12881_2014_Article_138.pdf AbstractBackgroundChromosome 9p21 variants are associated with cardiovascular disease (CVD) but not with any of its known risk markers. However, recent studies have suggested that the risk associated with 9p21 variation is modified by a prudent dietary pattern and smoking. We tested if the increased risk of CVD by the 9p21 single nucleotide polymorphism rs4977574 is modified by intakes of vegetables, fruits, alcohol, or wine, and if rs4977574 interacts with environmental factors on known CVD risk markers.MethodsMultivariable Cox regression analyses were performed in 23,949 individuals from the population-based prospective Malmö Diet and Cancer Study (MDCS), of whom 3,164 developed CVD during 15 years of follow-up. The rs4977574 variant (major allele: A; minor allele: G) was genotyped using TaqMan® Assay Design probes. Dietary data were collected at baseline using a modified diet history method. Cross-sectional analyses were performed in 4,828 MDCS participants with fasting blood levels of circulating risk factors measured at baseline.ResultsEach rs4977574 G allele was associated with a 16% increased incidence of CVD (95% confidence interval (CI), 1.10¿1.22). Higher vegetable intake (hazard ratio (HR), 0.95 [CI: 0.91¿0.996]), wine intake (HR, 0.91 [CI: 0.86¿0.96]), and total alcohol consumption (HR, 0.92 [CI: 0.86¿0.98]) were associated with lower CVD incidence. The increased CVD incidence by the G allele was restricted to individuals with medium or high vegetable intake (Pinteraction¿=¿0.043), and to non- and low consumers of wine (Pinteraction¿=¿0.029). Although rs4977574 did not associate with any known risk markers, stratification by vegetable intake and smoking suggested an interaction with rs4977574 on glycated hemoglobin and high-density lipoprotein cholesterol (Pinteraction¿=¿0.015 and 0.049, respectively).ConclusionsOur results indicate that rs4977574 interacts with vegetable and wine intake to affect the incidence of CVD, and suggest that an interaction may exist between environmental risk factors and rs4977574 on known risk markers of CVD. PMID: 25551366 --------------------- [2] Science. 2007 Jun 8;316(5830):1488-91. Epub 2007 May 3. A common allele on chromosome 9 associated with coronary heart disease. McPherson R1, Pertsemlidis A, Kavaslar N, Stewart A, Roberts R, Cox DR, Hinds DA, Pennacchio LA, Tybjaerg-Hansen A, Folsom AR, Boerwinkle E, Hobbs HH, Cohen JC. Author information AbstractCoronary heart disease (CHD) is a major cause of death in Western countries. We used genome-wide association scanning to identify a 58-kilobase interval on chromosome 9p21 that was consistently associated with CHD in six independent samples (more than 23,000 participants) from four Caucasian populations. This interval, which is located near the CDKN2A and CDKN2B genes, contains no annotated genes and is not associated with established CHD risk factors such as plasma lipoproteins, hypertension, or diabetes. Homozygotes for the risk allele make up 20 to 25% of Caucasians and have a approximately 30 to 40% increased risk of CHD. PMID: 17478681 --------------------------------- [3] J Intern Med. 2013 Sep;274(3):233-40. doi: 10.1111/joim.12063. Epub 2013 Mar 25. Chromosome 9p21 genetic variation explains 13% of cardiovascular disease incidence but does not improve risk prediction. Gränsbo K1, Almgren P, Sjögren M, Smith JG, Engström G, Hedblad B, Melander O. Author information AbstractOBJECTIVES:To evaluate the proportion of cardiovascular disease (CVD) incidence that is explained by genetic variation at chromosome 9p21 and to test whether such variation adds incremental information with regard to CVD prediction, beyond traditional risk factors. DESIGN, SETTING AND PARTICIPANTS:rs4977574 on chromosome 9p21 was genotyped in 24 777 subjects from the Malmö Diet and Cancer study who were free from CVD prior to the baseline examination. Association between genotype and incident CVD (n = 2668) during a median follow-up of 11.7 years was evaluated in multivariate Cox proportional hazard models. Analyses were performed in quartiles of baseline age, and linear trends in effect size across age groups were estimated in logistic regression models. RESULTS:In additive models, chromosome 9p21 significantly predicted CVD in the entire population (hazard ratio 1.17 per G allele, 95% confidence interval 1.11-1.23, P < 0.001). Effect estimates increased from the highest (Q4) to the lowest quartile (Q1) of baseline age, but this trend was not significant. The overall population attributable risk conferred by chromosome 9p21 in fully adjusted models was 13%, ranging from 17% in Q1 to 11% in Q4. Addition of chromosome 9p21 to traditional risk factors only marginally improved predictive accuracy. CONCLUSION:The high population attributable risk conferred by chromosome 9p21 suggests that future interventions interfering with downstream mechanisms of the genetic variation may affect CVD incidence over a broad range of ages. However, variation of chromosome 9p21 alone does not add clinically meaningful information in terms of CVD prediction beyond traditional risk factors at any age.
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