@article {6685, title = {Genetic loci associated with circulating phospholipid trans fatty acids: a meta-analysis of genome-wide association studies from the CHARGE Consortium.}, journal = {Am J Clin Nutr}, volume = {101}, year = {2015}, month = {2015 Feb}, pages = {398-406}, abstract = {

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 {\texttimes} 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 {\texttimes} 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 {\texttimes} 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.

}, keywords = {African Americans, Arachidonic Acid, Asian Americans, Biomarkers, European Continental Ancestry Group, Fatty Acids, Omega-6, Gene Frequency, Genetic Association Studies, Genetic Loci, Genotyping Techniques, Humans, Phospholipids, Polymorphism, Single Nucleotide, Trans Fatty Acids}, issn = {1938-3207}, doi = {10.3945/ajcn.114.094557}, author = {Mozaffarian, Dariush and Kabagambe, Edmond K and Johnson, Catherine O and Lemaitre, Rozenn N and Manichaikul, Ani and Sun, Qi and Foy, Millennia and Wang, Lu and Wiener, Howard and Irvin, Marguerite R and Rich, Stephen S and Wu, Hongyu and Jensen, Majken K and Chasman, Daniel I and Chu, Audrey Y and Fornage, Myriam and Steffen, Lyn and King, Irena B and McKnight, Barbara and Psaty, Bruce M and Djouss{\'e}, Luc and Chen, Ida Y-D and Wu, Jason H Y and Siscovick, David S and Ridker, Paul M and Tsai, Michael Y and Rimm, Eric B and Hu, Frank B and Arnett, Donna K} } @article {6568, title = {Mendelian randomization of blood lipids for coronary heart disease.}, journal = {Eur Heart J}, volume = {36}, year = {2015}, month = {2015 Mar 01}, pages = {539-50}, abstract = {

AIMS: To investigate the causal role of high-density lipoprotein cholesterol (HDL-C) and triglycerides in coronary heart disease (CHD) using multiple instrumental variables for Mendelian randomization.

METHODS AND RESULTS: We developed weighted allele scores based on single nucleotide polymorphisms (SNPs) with established associations with HDL-C, triglycerides, and low-density lipoprotein cholesterol (LDL-C). For each trait, we constructed two scores. The first was unrestricted, including all independent SNPs associated with the lipid trait identified from a prior meta-analysis (threshold P < 2 {\texttimes} 10(-6)); and the second a restricted score, filtered to remove any SNPs also associated with either of the other two lipid traits at P <= 0.01. Mendelian randomization meta-analyses were conducted in 17 studies including 62,199 participants and 12,099 CHD events. Both the unrestricted and restricted allele scores for LDL-C (42 and 19 SNPs, respectively) associated with CHD. For HDL-C, the unrestricted allele score (48 SNPs) was associated with CHD (OR: 0.53; 95\% CI: 0.40, 0.70), per 1 mmol/L higher HDL-C, but neither the restricted allele score (19 SNPs; OR: 0.91; 95\% CI: 0.42, 1.98) nor the unrestricted HDL-C allele score adjusted for triglycerides, LDL-C, or statin use (OR: 0.81; 95\% CI: 0.44, 1.46) showed a robust association. For triglycerides, the unrestricted allele score (67 SNPs) and the restricted allele score (27 SNPs) were both associated with CHD (OR: 1.62; 95\% CI: 1.24, 2.11 and 1.61; 95\% CI: 1.00, 2.59, respectively) per 1-log unit increment. However, the unrestricted triglyceride score adjusted for HDL-C, LDL-C, and statin use gave an OR for CHD of 1.01 (95\% CI: 0.59, 1.75).

CONCLUSION: The genetic findings support a causal effect of triglycerides on CHD risk, but a causal role for HDL-C, though possible, remains less certain.

}, keywords = {Case-Control Studies, Cholesterol, HDL, Coronary Artery Disease, Female, Gene Frequency, Genotype, Genotyping Techniques, Humans, Male, Mendelian Randomization Analysis, Middle Aged, Polymorphism, Single Nucleotide, Risk Assessment, Triglycerides}, issn = {1522-9645}, doi = {10.1093/eurheartj/eht571}, author = {Holmes, Michael V and Asselbergs, Folkert W and Palmer, Tom M and Drenos, Fotios and Lanktree, Matthew B and Nelson, Christopher P and Dale, Caroline E and Padmanabhan, Sandosh and Finan, Chris and Swerdlow, Daniel I and Tragante, Vinicius and van Iperen, Erik P A and Sivapalaratnam, Suthesh and Shah, Sonia and Elbers, Clara C and Shah, Tina and Engmann, Jorgen and Giambartolomei, Claudia and White, Jon and Zabaneh, Delilah and Sofat, Reecha and McLachlan, Stela and Doevendans, Pieter A and Balmforth, Anthony J and Hall, Alistair S and North, Kari E and Almoguera, Berta and Hoogeveen, Ron C and Cushman, Mary and Fornage, Myriam and Patel, Sanjay R and Redline, Susan and Siscovick, David S and Tsai, Michael Y and Karczewski, Konrad J and Hofker, Marten H and Verschuren, W Monique and Bots, Michiel L and van der Schouw, Yvonne T and Melander, Olle and Dominiczak, Anna F and Morris, Richard and Ben-Shlomo, Yoav and Price, Jackie and Kumari, Meena and Baumert, Jens and Peters, Annette and Thorand, Barbara and Koenig, Wolfgang and Gaunt, Tom R and Humphries, Steve E and Clarke, Robert and Watkins, Hugh and Farrall, Martin and Wilson, James G and Rich, Stephen S and de Bakker, Paul I W and Lange, Leslie A and Davey Smith, George and Reiner, Alex P and Talmud, Philippa J and Kivimaki, Mika and Lawlor, Debbie A and Dudbridge, Frank and Samani, Nilesh J and Keating, Brendan J and Hingorani, Aroon D and Casas, Juan P} }