Publications by authors named "Lisette Stolk"

65 Publications

Newborn DNA-methylation, childhood lung function, and the risks of asthma and COPD across the life course.

Eur Respir J 2019 04 4;53(4). Epub 2019 Apr 4.

MRC Integrative Epidemiology Unit, University of Bristol, UK School of Social and Community Medicine, University of Bristol, Bristol, UK.

Rationale: We aimed to identify differentially methylated regions (DMRs) in cord blood DNA associated with childhood lung function, asthma and chronic obstructive pulmonary disease (COPD) across the life course.

Methods: We meta-analysed epigenome-wide data of 1688 children from five cohorts to identify cord blood DMRs and their annotated genes, in relation to forced expiratory volume in 1 s (FEV), FEV/forced vital capacity (FVC) ratio and forced expiratory flow at 75% of FVC at ages 7-13 years. Identified DMRs were explored for associations with childhood asthma, adult lung function and COPD, gene expression and involvement in biological processes.

Results: We identified 59 DMRs associated with childhood lung function, of which 18 were associated with childhood asthma and nine with COPD in adulthood. Genes annotated to the top 10 identified DMRs were , , , , , , , , and . Differential gene expression in blood was observed for 32 DMRs in childhood and 18 in adulthood. Genes related with 16 identified DMRs were associated with respiratory developmental or pathogenic pathways.

Interpretation: Our findings suggest that the epigenetic status of the newborn affects respiratory health and disease across the life course.
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http://dx.doi.org/10.1183/13993003.01795-2018DOI Listing
April 2019

Disentangling the genetics of lean mass.

Am J Clin Nutr 2019 02;109(2):276-287

Icelandic Heart Association Holtasmari, Kopavogur, Iceland.

Background: Lean body mass (LM) plays an important role in mobility and metabolic function. We previously identified five loci associated with LM adjusted for fat mass in kilograms. Such an adjustment may reduce the power to identify genetic signals having an association with both lean mass and fat mass.

Objectives: To determine the impact of different fat mass adjustments on genetic architecture of LM and identify additional LM loci.

Methods: We performed genome-wide association analyses for whole-body LM (20 cohorts of European ancestry with n = 38,292) measured using dual-energy X-ray absorptiometry) or bioelectrical impedance analysis, adjusted for sex, age, age2, and height with or without fat mass adjustments (Model 1 no fat adjustment; Model 2 adjustment for fat mass as a percentage of body mass; Model 3 adjustment for fat mass in kilograms).

Results: Seven single-nucleotide polymorphisms (SNPs) in separate loci, including one novel LM locus (TNRC6B), were successfully replicated in an additional 47,227 individuals from 29 cohorts. Based on the strengths of the associations in Model 1 vs Model 3, we divided the LM loci into those with an effect on both lean mass and fat mass in the same direction and refer to those as "sumo wrestler" loci (FTO and MC4R). In contrast, loci with an impact specifically on LM were termed "body builder" loci (VCAN and ADAMTSL3). Using existing available genome-wide association study databases, LM increasing alleles of SNPs in sumo wrestler loci were associated with an adverse metabolic profile, whereas LM increasing alleles of SNPs in "body builder" loci were associated with metabolic protection.

Conclusions: In conclusion, we identified one novel LM locus (TNRC6B). Our results suggest that a genetically determined increase in lean mass might exert either harmful or protective effects on metabolic traits, depending on its relation to fat mass.
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http://dx.doi.org/10.1093/ajcn/nqy272DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6500901PMC
February 2019

Multi-ethnic SULT1A1 copy number profiling with multiplex ligation-dependent probe amplification.

Pharmacogenomics 2018 06 23;19(9):761-770. Epub 2018 May 23.

Department of Genetics & Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA.

Aim: To develop a SULT1A1 multiplex ligation-dependent probe amplification assay and to investigate multi-ethnic copy number variant frequencies.

Methods: A novel multiplex ligation-dependent probe amplification assay was developed and tested on 472 African-American, Asian, Caucasian, Hispanic and Ashkenazi Jewish individuals.

Results: The frequencies of atypical total copy number (i.e., greater or less than two) were 38.7% for Hispanics, 38.9% for Ashkenazi Jewish, 43.2% for Caucasians, 53.6% for Asians and 64.1% for African-Americans. Heterozygous SULT1A1 deletion carriers (slow sulfators) were most common among Caucasians (8.4%), whereas African-Americans had the highest frequencies of three or more copies (rapid sulfators; 60.9%).

Conclusion: Different ethnic and racial populations have varying degrees of SULT1A1-mediated sulfation activity, which warrants further research and that may have utility for drug response prediction among SULT1A1-metabolized medications.
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http://dx.doi.org/10.2217/pgs-2018-0047DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6021911PMC
June 2018

Genetic Determinants of Circulating Estrogen Levels and Evidence of a Causal Effect of Estradiol on Bone Density in Men.

J Clin Endocrinol Metab 2018 03;103(3):991-1004

Department of Clinical and Experimental Medicine, Katholieke Universiteit Leuven, Laboratory of Clinical and Experimental Endocrinology, Leuven, Belgium.

Context: Serum estradiol (E2) and estrone (E1) levels exhibit substantial heritability.

Objective: To investigate the genetic regulation of serum E2 and E1 in men.

Design, Setting, And Participants: Genome-wide association study in 11,097 men of European origin from nine epidemiological cohorts.

Main Outcome Measures: Genetic determinants of serum E2 and E1 levels.

Results: Variants in/near CYP19A1 demonstrated the strongest evidence for association with E2, resolving to three independent signals. Two additional independent signals were found on the X chromosome; FAMily with sequence similarity 9, member B (FAM9B), rs5934505 (P = 3.4 × 10-8) and Xq27.3, rs5951794 (P = 3.1 × 10-10). E1 signals were found in CYP19A1 (rs2899472, P = 5.5 × 10-23), in Tripartite motif containing 4 (TRIM4; rs17277546, P = 5.8 × 10-14), and CYP11B1/B2 (rs10093796, P = 1.2 × 10-8). E2 signals in CYP19A1 and FAM9B were associated with bone mineral density (BMD). Mendelian randomization analysis suggested a causal effect of serum E2 on BMD in men. A 1 pg/mL genetically increased E2 was associated with a 0.048 standard deviation increase in lumbar spine BMD (P = 2.8 × 10-12). In men and women combined, CYP19A1 alleles associated with higher E2 levels were associated with lower degrees of insulin resistance.

Conclusions: Our findings confirm that CYP19A1 is an important genetic regulator of E2 and E1 levels and strengthen the causal importance of E2 for bone health in men. We also report two independent loci on the X-chromosome for E2, and one locus each in TRIM4 and CYP11B1/B2, for E1.
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http://dx.doi.org/10.1210/jc.2017-02060DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5868407PMC
March 2018

Genetically defined elevated homocysteine levels do not result in widespread changes of DNA methylation in leukocytes.

PLoS One 2017 30;12(10):e0182472. Epub 2017 Oct 30.

Framingham Heart Study, Framingham, MA, United States of America.

Background: DNA methylation is affected by the activities of the key enzymes and intermediate metabolites of the one-carbon pathway, one of which involves homocysteine. We investigated the effect of the well-known genetic variant associated with mildly elevated homocysteine: MTHFR 677C>T independently and in combination with other homocysteine-associated variants, on genome-wide leukocyte DNA-methylation.

Methods: Methylation levels were assessed using Illumina 450k arrays on 9,894 individuals of European ancestry from 12 cohort studies. Linear-mixed-models were used to study the association of additive MTHFR 677C>T and genetic-risk score (GRS) based on 18 homocysteine-associated SNPs, with genome-wide methylation.

Results: Meta-analysis revealed that the MTHFR 677C>T variant was associated with 35 CpG sites in cis, and the GRS showed association with 113 CpG sites near the homocysteine-associated variants. Genome-wide analysis revealed that the MTHFR 677C>T variant was associated with 1 trans-CpG (nearest gene ZNF184), while the GRS model showed association with 5 significant trans-CpGs annotated to nearest genes PTF1A, MRPL55, CTDSP2, CRYM and FKBP5.

Conclusions: Our results do not show widespread changes in DNA-methylation across the genome, and therefore do not support the hypothesis that mildly elevated homocysteine is associated with widespread methylation changes in leukocytes.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0182472PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5662081PMC
November 2017

Homocysteine levels associate with subtle changes in leukocyte DNA methylation: an epigenome-wide analysis.

Epigenomics 2017 11 9;9(11):1403-1422. Epub 2017 Oct 9.

Department of Clinical Chemistry, Erasmus University Medical Center, Rotterdam, The Netherlands.

Aim: Homocysteine (Hcy) is a sensitive marker of one-carbon metabolism. Higher Hcy levels have been associated with global DNA hypomethylation. We investigated the association between plasma Hcy and epigenome-wide DNA methylation in leukocytes.

Methods: Methylation was measured using Illumina 450 k arrays in 2035 individuals from six cohorts. Hcy-associated differentially methylated positions and regions were identified using meta-analysis.

Results: Three differentially methylated positions cg21607669 (SLC27A1), cg26382848 (AJUBA) and cg10701000 (KCNMA1) at chromosome 19, 14 and 10, respectively, were significantly associated with Hcy. In addition, we identified 68 Hcy-associated differentially methylated regions, the most significant of which was a 1.8-kb spanning domain (TNXB/ATF6B) at chromosome 6.

Conclusion: We identified novel epigenetic loci associated with Hcy levels, of which specific role needs to be further validated.
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http://dx.doi.org/10.2217/epi-2017-0038DOI Listing
November 2017

Large meta-analysis of genome-wide association studies identifies five loci for lean body mass.

Nat Commun 2017 07 19;8(1):80. Epub 2017 Jul 19.

Division of Statistical Genomics, Department of Genetics, Washington University School of Medicine, St Louis, MO, 63110, USA.

Lean body mass, consisting mostly of skeletal muscle, is important for healthy aging. We performed a genome-wide association study for whole body (20 cohorts of European ancestry with n = 38,292) and appendicular (arms and legs) lean body mass (n = 28,330) measured using dual energy X-ray absorptiometry or bioelectrical impedance analysis, adjusted for sex, age, height, and fat mass. Twenty-one single-nucleotide polymorphisms were significantly associated with lean body mass either genome wide (p < 5 × 10) or suggestively genome wide (p < 2.3 × 10). Replication in 63,475 (47,227 of European ancestry) individuals from 33 cohorts for whole body lean body mass and in 45,090 (42,360 of European ancestry) subjects from 25 cohorts for appendicular lean body mass was successful for five single-nucleotide polymorphisms in/near HSD17B11, VCAN, ADAMTSL3, IRS1, and FTO for total lean body mass and for three single-nucleotide polymorphisms in/near VCAN, ADAMTSL3, and IRS1 for appendicular lean body mass. Our findings provide new insight into the genetics of lean body mass.Lean body mass is a highly heritable trait and is associated with various health conditions. Here, Kiel and colleagues perform a meta-analysis of genome-wide association studies for whole body lean body mass and find five novel genetic loci to be significantly associated.
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http://dx.doi.org/10.1038/s41467-017-00031-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5517526PMC
July 2017

Genomic analyses identify hundreds of variants associated with age at menarche and support a role for puberty timing in cancer risk.

Nat Genet 2017 Jun 24;49(6):834-841. Epub 2017 Apr 24.

Institute of Genetics and Biophysics, CNR, Naples, Italy.

The timing of puberty is a highly polygenic childhood trait that is epidemiologically associated with various adult diseases. Using 1000 Genomes Project-imputed genotype data in up to ∼370,000 women, we identify 389 independent signals (P < 5 × 10) for age at menarche, a milestone in female pubertal development. In Icelandic data, these signals explain ∼7.4% of the population variance in age at menarche, corresponding to ∼25% of the estimated heritability. We implicate ∼250 genes via coding variation or associated expression, demonstrating significant enrichment in neural tissues. Rare variants near the imprinted genes MKRN3 and DLK1 were identified, exhibiting large effects when paternally inherited. Mendelian randomization analyses suggest causal inverse associations, independent of body mass index (BMI), between puberty timing and risks for breast and endometrial cancers in women and prostate cancer in men. In aggregate, our findings highlight the complexity of the genetic regulation of puberty timing and support causal links with cancer susceptibility.
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http://dx.doi.org/10.1038/ng.3841DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5841952PMC
June 2017

Epigenome-wide association study of body mass index, and the adverse outcomes of adiposity.

Nature 2017 01 21;541(7635):81-86. Epub 2016 Dec 21.

German Center for Diabetes Research (DZD), München-Neuherberg, Germany.

Approximately 1.5 billion people worldwide are overweight or affected by obesity, and are at risk of developing type 2 diabetes, cardiovascular disease and related metabolic and inflammatory disturbances. Although the mechanisms linking adiposity to associated clinical conditions are poorly understood, recent studies suggest that adiposity may influence DNA methylation, a key regulator of gene expression and molecular phenotype. Here we use epigenome-wide association to show that body mass index (BMI; a key measure of adiposity) is associated with widespread changes in DNA methylation (187 genetic loci with P < 1 × 10, range P = 9.2 × 10 to 6.0 × 10; n = 10,261 samples). Genetic association analyses demonstrate that the alterations in DNA methylation are predominantly the consequence of adiposity, rather than the cause. We find that methylation loci are enriched for functional genomic features in multiple tissues (P < 0.05), and show that sentinel methylation markers identify gene expression signatures at 38 loci (P < 9.0 × 10, range P = 5.5 × 10 to 6.1 × 10, n = 1,785 samples). The methylation loci identify genes involved in lipid and lipoprotein metabolism, substrate transport and inflammatory pathways. Finally, we show that the disturbances in DNA methylation predict future development of type 2 diabetes (relative risk per 1 standard deviation increase in methylation risk score: 2.3 (2.07-2.56); P = 1.1 × 10). Our results provide new insights into the biologic pathways influenced by adiposity, and may enable development of new strategies for prediction and prevention of type 2 diabetes and other adverse clinical consequences of obesity.
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http://dx.doi.org/10.1038/nature20784DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5570525PMC
January 2017

Genome-wide analysis identifies 12 loci influencing human reproductive behavior.

Nat Genet 2016 12 31;48(12):1462-1472. Epub 2016 Oct 31.

Department of Internal Medicine, Erasmus Medical Center, Rotterdam, the Netherlands.

The genetic architecture of human reproductive behavior-age at first birth (AFB) and number of children ever born (NEB)-has a strong relationship with fitness, human development, infertility and risk of neuropsychiatric disorders. However, very few genetic loci have been identified, and the underlying mechanisms of AFB and NEB are poorly understood. We report a large genome-wide association study of both sexes including 251,151 individuals for AFB and 343,072 individuals for NEB. We identified 12 independent loci that are significantly associated with AFB and/or NEB in a SNP-based genome-wide association study and 4 additional loci associated in a gene-based effort. These loci harbor genes that are likely to have a role, either directly or by affecting non-local gene expression, in human reproduction and infertility, thereby increasing understanding of these complex traits.
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http://dx.doi.org/10.1038/ng.3698DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5695684PMC
December 2016

Genetic variation and bone mineral density in long-term adult survivors of childhood cancer.

Pediatr Blood Cancer 2016 12 31;63(12):2212-2220. Epub 2016 Aug 31.

Department of Pediatric Oncology/Hematology, Erasmus MC-Sophia Children's Hospital Rotterdam, Rotterdam, The Netherlands.

Purpose: Despite similarities in upfront treatment of childhood cancer, not every adult survivor of childhood cancer (CCS) has an impaired bone mineral density (BMD). No data are available on the role of genetic variation on impairment of BMD in CCS.

Methods: This cross-sectional single-center cohort study included 334 adult CCSs (median follow-up time after cessation of treatment: 15 years; median age at follow-up: 26 years). Total body BMD (BMD ) and lumbar spine BMD (BMD ) were measured by dual x-ray absorptiometry. We selected 12 candidate single-nucleotide polymorphisms (SNPs) in 11 genes (COL1A1, TNFSF11, TNFRSF11, TNRFSA11B, VDR, ESR1, WLS, LRP5, MTHFR, MTRR, IL-6).

Results: Multivariate analyses revealed that lower BMD was associated with lower weight and height at follow-up, male sex, and previously administered radiotherapy. Survivors with the homozygous minor allele (GG) genotype of rs2504063 (ESR1: estrogen receptor type 1) had a lower BMD values (-1.16 vs. -0.82; P = 0.01) than those with the AG/AA genotype; however, BMD was not different. Carriers of two minor alleles (GG) of rs599083 (LRP5: low-density lipoprotein receptor) revealed lower BMD (-1.20 vs. -0.78; P = 0.02) and lower BMD (-0.95 vs. -0.46; P = 0.01) values than those with the TT/TG genotype.

Conclusion: CCSs who are carriers of candidate SNPs in the ESR1 or LRP5 genes seem to have an impaired bone mass at an early adult age. Information on genetic variation, in addition to patient- and treatment-related factors, may be helpful in identifying survivors who are at risk for low bone density after childhood cancer treatment.
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http://dx.doi.org/10.1002/pbc.26198DOI Listing
December 2016

Lower sex hormone levels are associated with more chronic musculoskeletal pain in community-dwelling elderly women.

Pain 2016 07;157(7):1425-1431

Departments of Internal Medicine.

Chronic pain is more prevalent in women than in men, with increasing differences between sexes in advanced age. This could be caused by differences in sex hormone levels. We therefore studied the relationship between sex hormones and the prevalence and incidence of chronic pain. The association between sex hormone levels and chronic pain was examined in 9717 participants aged 45 years and older from the Rotterdam Study, a population-based study. Chronic pain was defined as pain in the lower back, hands, knees and/or hips for at least 3 months. Sex hormone levels included estrogen, testosterone, androstenedione, and 17-hydroxyprogesterone. Relationships between hormones and prevalent and new onset chronic pain were analyzed using linear and logistic regression, stratified by gender. Women with androstenedione or estradiol levels in the lowest tertile had more chronic pain (odds ratio, 1.20; 95% CI, 1.03-1.39 and odds ratio, 1.27; 95% CI, 1.10-1.48, respectively). Mean estradiol levels were lower among men with chronic pain (mean difference -3.88 pmol/L; P = 0.005). Lowest tertile 17-hydroxyprogesterone in women was associated with 38% more new onset pain. All these associations were independent from age, body mass index, health and lifestyle factors, and osteoarthritis. Lower sex hormone levels are associated with chronic musculoskeletal pain, independent from lifestyle and health-related factors, in community-dwelling elderly women. These results suggest that sex hormones play a role in chronic pain and should be taken into account when a patient presents with chronic pain. Therefore, sex hormones may be a potential treatment target for these patients.
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http://dx.doi.org/10.1097/j.pain.0000000000000535DOI Listing
July 2016

The transcriptional landscape of age in human peripheral blood.

Nat Commun 2015 Oct 22;6:8570. Epub 2015 Oct 22.

Department of Internal Medicine, Erasmus Medical Centre Rotterdam, Rotterdam 3000CA, The Netherlands.

Disease incidences increase with age, but the molecular characteristics of ageing that lead to increased disease susceptibility remain inadequately understood. Here we perform a whole-blood gene expression meta-analysis in 14,983 individuals of European ancestry (including replication) and identify 1,497 genes that are differentially expressed with chronological age. The age-associated genes do not harbor more age-associated CpG-methylation sites than other genes, but are instead enriched for the presence of potentially functional CpG-methylation sites in enhancer and insulator regions that associate with both chronological age and gene expression levels. We further used the gene expression profiles to calculate the 'transcriptomic age' of an individual, and show that differences between transcriptomic age and chronological age are associated with biological features linked to ageing, such as blood pressure, cholesterol levels, fasting glucose, and body mass index. The transcriptomic prediction model adds biological relevance and complements existing epigenetic prediction models, and can be used by others to calculate transcriptomic age in external cohorts.
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http://dx.doi.org/10.1038/ncomms9570DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4639797PMC
October 2015

Causal mechanisms and balancing selection inferred from genetic associations with polycystic ovary syndrome.

Nat Commun 2015 Sep 29;6:8464. Epub 2015 Sep 29.

MRC Epidemiology Unit, University of Cambridge School of Clinical Medicine, Box 285 Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge Biomedical Campus, Cambridge CB2 0QQ, UK.

Polycystic ovary syndrome (PCOS) is the most common reproductive disorder in women, yet there is little consensus regarding its aetiology. Here we perform a genome-wide association study of PCOS in up to 5,184 self-reported cases of White European ancestry and 82,759 controls, with follow-up in a further ∼2,000 clinically validated cases and ∼100,000 controls. We identify six signals for PCOS at genome-wide statistical significance (P<5 × 10(-8)), in/near genes ERBB4/HER4, YAP1, THADA, FSHB, RAD50 and KRR1. Variants in/near three of the four epidermal growth factor receptor genes (ERBB2/HER2, ERBB3/HER3 and ERBB4/HER4) are associated with PCOS at or near genome-wide significance. Mendelian randomization analyses indicate causal roles in PCOS aetiology for higher BMI (P=2.5 × 10(-9)), higher insulin resistance (P=6 × 10(-4)) and lower serum sex hormone binding globulin concentrations (P=5 × 10(-4)). Furthermore, genetic susceptibility to later menopause is associated with higher PCOS risk (P=1.6 × 10(-8)) and PCOS-susceptibility alleles are associated with higher serum anti-Müllerian hormone concentrations in girls (P=8.9 × 10(-5)). This large-scale study implicates an aetiological role of the epidermal growth factor receptors, infers causal mechanisms relevant to clinical management and prevention, and suggests balancing selection mechanisms involved in PCOS risk.
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http://dx.doi.org/10.1038/ncomms9464DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4598835PMC
September 2015

Large-scale genomic analyses link reproductive aging to hypothalamic signaling, breast cancer susceptibility and BRCA1-mediated DNA repair.

Nat Genet 2015 Nov 28;47(11):1294-1303. Epub 2015 Sep 28.

Institute for Maternal and Child Health - IRCCS "Burlo Garofolo", 34137 Trieste, Italy.

Menopause timing has a substantial impact on infertility and risk of disease, including breast cancer, but the underlying mechanisms are poorly understood. We report a dual strategy in ∼70,000 women to identify common and low-frequency protein-coding variation associated with age at natural menopause (ANM). We identified 44 regions with common variants, including two regions harboring additional rare missense alleles of large effect. We found enrichment of signals in or near genes involved in delayed puberty, highlighting the first molecular links between the onset and end of reproductive lifespan. Pathway analyses identified major association with DNA damage response (DDR) genes, including the first common coding variant in BRCA1 associated with any complex trait. Mendelian randomization analyses supported a causal effect of later ANM on breast cancer risk (∼6% increase in risk per year; P = 3 × 10(-14)), likely mediated by prolonged sex hormone exposure rather than DDR mechanisms.
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http://dx.doi.org/10.1038/ng.3412DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4661791PMC
November 2015

Trans-ancestry genome-wide association study identifies 12 genetic loci influencing blood pressure and implicates a role for DNA methylation.

Nat Genet 2015 11 21;47(11):1282-1293. Epub 2015 Sep 21.

Saw Swee Hock School of Public Health, National University of Singapore and National University Health System, Singapore.

We carried out a trans-ancestry genome-wide association and replication study of blood pressure phenotypes among up to 320,251 individuals of East Asian, European and South Asian ancestry. We find genetic variants at 12 new loci to be associated with blood pressure (P = 3.9 × 10(-11) to 5.0 × 10(-21)). The sentinel blood pressure SNPs are enriched for association with DNA methylation at multiple nearby CpG sites, suggesting that, at some of the loci identified, DNA methylation may lie on the regulatory pathway linking sequence variation to blood pressure. The sentinel SNPs at the 12 new loci point to genes involved in vascular smooth muscle (IGFBP3, KCNK3, PDE3A and PRDM6) and renal (ARHGAP24, OSR1, SLC22A7 and TBX2) function. The new and known genetic variants predict increased left ventricular mass, circulating levels of NT-proBNP, and cardiovascular and all-cause mortality (P = 0.04 to 8.6 × 10(-6)). Our results provide new evidence for the role of DNA methylation in blood pressure regulation.
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http://dx.doi.org/10.1038/ng.3405DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4719169PMC
November 2015

Prenatal parental tobacco smoking, gene specific DNA methylation, and newborns size: the Generation R study.

Clin Epigenetics 2015 11;7:83. Epub 2015 Aug 11.

Department of Obstetrics and Gynecology, Erasmus MC, University Medical Centre, Ee-building Room 2271a, PO Box 1738, 3000 DR Rotterdam, The Netherlands.

Background: Deleterious effects of prenatal tobacco smoking on fetal growth and newborn weight are well-established. One of the proposed mechanisms underlying this relationship is alterations in epigenetic programming. We selected 506 newborns from a population-based prospective birth cohort in the Netherlands. Prenatal parental tobacco smoking was assessed using self-reporting questionnaires. Information on birth outcomes was obtained from medical records. The deoxyribonucleic acid (DNA) methylation of the growth genes IGF2DMR and H19 was measured in newborn umbilical cord white blood cells. Associations were assessed between parental tobacco smoking and DNA methylation using linear mixed models and adjusted for potential confounders.

Results: The DNA methylation levels of IGF2DMR and H19 in the non-smoking group were median (90 % range), 54.0 % (44.6-62.0), and 30.0 % (25.5-34.0), in the first trimester only smoking group 52.2 % (44.5-61.1) and 30.8 % (27.1-34.1), and in the continued smoking group 51.6 % (43.9-61.3) and 30.2 % (23.7-34.8), respectively. Continued prenatal maternal smoking was inversely associated with IGF2DMR methylation (β = -1.03, 95 % CI -1.76; -0.30) in a dose-dependent manner (P-trend = 0.030). This association seemed to be slightly more profound among newborn girls (β = -1.38, 95 % CI -2.63; -0.14) than boys (β = -0.72, 95 % CI -1.68; 0.24). H19 methylation was also inversely associated continued smoking <5 cigarettes/day (β = -0.96, 95 % CI -1.78; -0.14). Moreover, the association between maternal smoking and newborns small for gestational age seems to be partially explained by IGF2DMR methylation (β = -0.095, 95 % CI -0.249; -0.018). Among non-smoking mothers, paternal tobacco smoking was not associated with IGF2DMR or H19 methylation.

Conclusions: Maternal smoking is inversely associated with IGF2DMR methylation in newborns, which can be one of the underlying mechanisms through which smoking affects fetal growth.
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http://dx.doi.org/10.1186/s13148-015-0115-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4531498PMC
August 2015

Rare coding variants and X-linked loci associated with age at menarche.

Nat Commun 2015 Aug 4;6:7756. Epub 2015 Aug 4.

Human Genetics Center, School of Public Health, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA.

More than 100 loci have been identified for age at menarche by genome-wide association studies; however, collectively these explain only ∼3% of the trait variance. Here we test two overlooked sources of variation in 192,974 European ancestry women: low-frequency protein-coding variants and X-chromosome variants. Five missense/nonsense variants (in ALMS1/LAMB2/TNRC6A/TACR3/PRKAG1) are associated with age at menarche (minor allele frequencies 0.08-4.6%; effect sizes 0.08-1.25 years per allele; P<5 × 10(-8)). In addition, we identify common X-chromosome loci at IGSF1 (rs762080, P=9.4 × 10(-13)) and FAAH2 (rs5914101, P=4.9 × 10(-10)). Highlighted genes implicate cellular energy homeostasis, post-transcriptional gene silencing and fatty-acid amide signalling. A frequently reported mutation in TACR3 for idiopathic hypogonatrophic hypogonadism (p.W275X) is associated with 1.25-year-later menarche (P=2.8 × 10(-11)), illustrating the utility of population studies to estimate the penetrance of reportedly pathogenic mutations. Collectively, these novel variants explain ∼0.5% variance, indicating that these overlooked sources of variation do not substantially explain the 'missing heritability' of this complex trait.
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http://dx.doi.org/10.1038/ncomms8756DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4538850PMC
August 2015

Tobacco smoking is associated with methylation of genes related to coronary artery disease.

Clin Epigenetics 2015 14;7:54. Epub 2015 May 14.

Department of Epidemiology, Erasmus University Medical Centre, 's Gravendijkwal 230, 3015 CE Rotterdam, The Netherlands.

Background: Tobacco smoking, a risk factor for coronary artery disease (CAD), is known to modify DNA methylation. We hypothesized that tobacco smoking modifies methylation of the genes identified for CAD by genome-wide association study (GWAS).

Results: We selected genomic regions based on 150 single-nucleotide polymorphisms (SNPs) identified in the largest GWAS on CAD. We investigated the association between current smoking and the CpG sites within and near these CAD-related genes. Methylation was measured with the Illumina Human Methylation 450K array in whole blood of 724 Caucasian subjects from the Rotterdam Study, a Dutch population based cohort study. A total of 3669 CpG sites within 169 CAD-related genes were studied for association with current compared to never smoking. Fifteen CpG sites were significantly associated after correction for multiple testing (Bonferroni-corrected p value <1.4 × 10(-5)). These sites were located in the genes TERT, SARS, GNGT2, SMG6, SKI, TOM1L2, SIPA1, MRAS, CDKN1A, LRRC2, FES and RPH3A. In 12 sites, current smoking was associated with a 1.2 to 2.4 % lower methylation compared to never smoking; and in three sites, it was associated with a 1.2 to 1.8 % higher methylation. The effect estimates were lower in 10 of the 15 CpG sites when comparing current to former smoking. One CpG site, cg05603985 (SKI), was found to be associated with expression of nearby CAD-related gene PRKCZ.

Conclusions: Our study suggests an effect of tobacco smoking on DNA methylation of CAD-related genes and thus provides novel insights in the pathways that link tobacco smoking to risk of CAD.
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http://dx.doi.org/10.1186/s13148-015-0088-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4443552PMC
May 2015

Genome-wide association study in an admixed case series reveals IL12A as a new candidate in Behçet disease.

PLoS One 2015 23;10(3):e0119085. Epub 2015 Mar 23.

Internal medicine, Section immunology, Erasmus Medical Center, Rotterdam, The Netherlands; Department of Immunology, Erasmus Medical Center, Rotterdam, The Netherlands.

Introduction: The etiology of Behçet's disease (BD) is unknown, but widely considered an excessive T-cell mediated inflammatory response in a genetically susceptible host. Recent genome-wide association studies (GWAS) have shown limited number of novel loci-associations. The rarity and unequal distribution of the disease prevalence amongst different ethnic backgrounds have hampered the use of GWAS in cohorts of mixed ethnicity and sufficient sample size. However, novel statistical approaches have now enabled GWAS in admixed cohorts.

Methods: We ran a GWAS on 336 BD cases and 5,843 controls. The cases consisted of Western Europeans, Middle Eastern and Turkish individuals. Participants from the Generation R study, a multiethnic birth cohort in Rotterdam, The Netherlands were used as controls. All samples were genotyped and data was combined. Linear regression models were corrected for population stratification using Genomic Principal Components and Linear Mixed Modelling. Meta-analysis was performed on selected results previously published.

Results: We identified SNPs associated at genome-wide significant level mapping to the 6p21.33 (HLA) region. In addition to this known signal two potential novel associations on chromosomes 6 and 18 were identified, yet with low minor allele frequencies. Extended meta-analysis reveal a GWS association with the IL12A variant rs17810546 on chromosome 3.

Discussion: We demonstrate that new statistical techniques enable GWAS analyses in a limited sized cohort of mixed ethnicity. After implementation, we confirmed the central role of the HLA region in the disease and identified new regions of interest. Moreover, we validated the association of a variant in the IL2A gene by meta-analysis with previous work. These findings enhance our knowledge of genetic associations and BD, and provide further justification for pursuing collective initiatives in genetic studies given the low prevalence of this and other rare diseases.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0119085PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4370488PMC
February 2016

Genetic studies of body mass index yield new insights for obesity biology.

Nature 2015 Feb;518(7538):197-206

Department of Genetics, University Medical Center Groningen, University of Groningen, 9700 RB Groningen, The Netherlands.

Obesity is heritable and predisposes to many diseases. To understand the genetic basis of obesity better, here we conduct a genome-wide association study and Metabochip meta-analysis of body mass index (BMI), a measure commonly used to define obesity and assess adiposity, in up to 339,224 individuals. This analysis identifies 97 BMI-associated loci (P < 5 × 10(-8)), 56 of which are novel. Five loci demonstrate clear evidence of several independent association signals, and many loci have significant effects on other metabolic phenotypes. The 97 loci account for ∼2.7% of BMI variation, and genome-wide estimates suggest that common variation accounts for >20% of BMI variation. Pathway analyses provide strong support for a role of the central nervous system in obesity susceptibility and implicate new genes and pathways, including those related to synaptic function, glutamate signalling, insulin secretion/action, energy metabolism, lipid biology and adipogenesis.
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http://dx.doi.org/10.1038/nature14177DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4382211PMC
February 2015

New genetic loci link adipose and insulin biology to body fat distribution.

Nature 2015 Feb;518(7538):187-196

Department of Genetics, University Medical Center Groningen, University of Groningen, 9700 RB Groningen, The Netherlands.

Body fat distribution is a heritable trait and a well-established predictor of adverse metabolic outcomes, independent of overall adiposity. To increase our understanding of the genetic basis of body fat distribution and its molecular links to cardiometabolic traits, here we conduct genome-wide association meta-analyses of traits related to waist and hip circumferences in up to 224,459 individuals. We identify 49 loci (33 new) associated with waist-to-hip ratio adjusted for body mass index (BMI), and an additional 19 loci newly associated with related waist and hip circumference measures (P < 5 × 10(-8)). In total, 20 of the 49 waist-to-hip ratio adjusted for BMI loci show significant sexual dimorphism, 19 of which display a stronger effect in women. The identified loci were enriched for genes expressed in adipose tissue and for putative regulatory elements in adipocytes. Pathway analyses implicated adipogenesis, angiogenesis, transcriptional regulation and insulin resistance as processes affecting fat distribution, providing insight into potential pathophysiological mechanisms.
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http://dx.doi.org/10.1038/nature14132DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4338562PMC
February 2015

Homocysteine and DNA methylation: a review of animal and human literature.

Mol Genet Metab 2014 Dec 14;113(4):243-52. Epub 2014 Oct 14.

Department of Clinical Chemistry, Erasmus University Medical Center, Rotterdam, The Netherlands. Electronic address:

Homocysteine (Hcy) is a sulfur-containing non-protein forming amino acid, which is synthesized from methionine as an important intermediate in the one-carbon pathway. High concentrations of Hcy in a condition called hyperhomocysteinemia (HHcy) are an independent risk factor for several disorders including cardiovascular diseases and osteoporotic fractures. Since Hcy is produced as a byproduct of the methyltransferase reaction, alteration in DNA methylation is studied as one of the underlying mechanisms of HHcy-associated disorders. In animal models, elevated Hcy concentrations are induced either by diet (high methionine, low B-vitamins, or both), gene knockouts (Mthfr, Cbs, Mtrr or Mtr) or combination of both to investigate their effects on DNA methylation or its markers. In humans, most of the literature involves case-control studies concerning patients. The focus of this review is to study existing literature on HHcy and its role in relation to DNA methylation. Apart from this, a few studies investigated the effect of Hcy-lowering trials on restoring DNA methylation patterns, by giving a folic acid or B-vitamin supplemented diet. These studies which were conducted in animal models as well as humans were included in this review.
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http://dx.doi.org/10.1016/j.ymgme.2014.10.006DOI Listing
December 2014

Determinants of maternal pregnancy one-carbon metabolism and newborn human DNA methylation profiles.

Reproduction 2014 Dec;148(6):581-92

The Generation R Study GroupDepartment of Child and Adolescent PsychiatryDepartment of Obstetrics and GynecologyDepartment of Internal MedicineDepartment of EpidemiologyDepartment of PaediatricsDepartment of BiostatisticsDepartment of PsychiatryErasmus MC, University Medical Centre Rotterdam, Dr Molewaterplein 50, 3015 GE Rotterdam, The Netherlands

Maternal one-carbon (1-C) metabolism provides methylgroups for fetal development and programing by DNA methylation as one of the underlying epigenetic mechanisms. We aimed to investigate maternal 1-C biomarkers, folic acid supplement use, and MTHFR C677T genotype as determinants of 1-C metabolism in early pregnancy in association with newborn DNA methylation levels of fetal growth and neurodevelopment candidate genes. The participants were 463 mother-child pairs of Dutch national origin from a large population-based birth cohort in Rotterdam, The Netherlands. In early pregnancy (median 13.0 weeks, 90% range 10.4-17.1), we assessed the maternal folate and homocysteine blood concentrations, folic acid supplement use, and the MTHFR C677T genotype in mothers and newborns. In newborns, DNA methylation was measured in umbilical cord blood white blood cells at 11 regions of the seven genes: NR3C1, DRD4, 5-HTT, IGF2DMR, H19, KCNQ1OT1, and MTHFR. The associations between the 1-C determinants and DNA methylation were examined using linear mixed models. An association was observed between maternal folate deficiency and lower newborn DNA methylation, which attenuated after adjustment for potential confounders. The maternal MTHFR TT genotype was significantly associated with lower DNA methylation. However, maternal homocysteine and folate concentrations, folic acid supplement use, and the MTHFR genotype in the newborn were not associated with newborn DNA methylation. The maternal MTHFR C677T genotype, as a determinant of folate status and 1-C metabolism, is associated with variations in the epigenome of a selection of genes in newborns. Research on the implications of these variations in methylation on gene expression and health is recommended.
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http://dx.doi.org/10.1530/REP-14-0260DOI Listing
December 2014

Parent-of-origin-specific allelic associations among 106 genomic loci for age at menarche.

Nature 2014 Oct 23;514(7520):92-97. Epub 2014 Jul 23.

Institute for Maternal and Child Health - IRCCS "Burlo Garofolo" - Trieste, Italy.

Age at menarche is a marker of timing of puberty in females. It varies widely between individuals, is a heritable trait and is associated with risks for obesity, type 2 diabetes, cardiovascular disease, breast cancer and all-cause mortality. Studies of rare human disorders of puberty and animal models point to a complex hypothalamic-pituitary-hormonal regulation, but the mechanisms that determine pubertal timing and underlie its links to disease risk remain unclear. Here, using genome-wide and custom-genotyping arrays in up to 182,416 women of European descent from 57 studies, we found robust evidence (P < 5 × 10(-8)) for 123 signals at 106 genomic loci associated with age at menarche. Many loci were associated with other pubertal traits in both sexes, and there was substantial overlap with genes implicated in body mass index and various diseases, including rare disorders of puberty. Menarche signals were enriched in imprinted regions, with three loci (DLK1-WDR25, MKRN3-MAGEL2 and KCNK9) demonstrating parent-of-origin-specific associations concordant with known parental expression patterns. Pathway analyses implicated nuclear hormone receptors, particularly retinoic acid and γ-aminobutyric acid-B2 receptor signalling, among novel mechanisms that regulate pubertal timing in humans. Our findings suggest a genetic architecture involving at least hundreds of common variants in the coordinated timing of the pubertal transition.
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http://dx.doi.org/10.1038/nature13545DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4185210PMC
October 2014

Methylation of migraine-related genes in different tissues of the rat.

PLoS One 2014 7;9(3):e87616. Epub 2014 Mar 7.

Dept. of Internal Medicine, Div. of Pharmacology, Erasmus Medical Center, Rotterdam, The Netherlands.

17ß-Estradiol, an epigenetic modulator, is involved in the increased prevalence of migraine in women. Together with the prophylactic efficacy of valproate, which influences DNA methylation and histone modification, this points to the involvement of epigenetic mechanisms. Epigenetic studies are often performed on leukocytes, but it is unclear to what extent methylation is similar in other tissues. Therefore, we investigated methylation of migraine-related genes that might be epigenetically regulated (CGRP-ergic pathway, estrogen receptors, endothelial NOS, as well as MTHFR) in different migraine-related tissues and compared this to methylation in rat as well as human leukocytes. Further, we studied whether 17ß-estradiol has a prominent role in methylation of these genes. Female rats (n = 35) were ovariectomized or sham-operated and treated with 17β-estradiol or placebo. DNA was isolated and methylation was assessed through bisulphite treatment and mass spectrometry. Human methylation data were obtained using the Illumina 450k genome-wide methylation array in 395 female subjects from a population-based cohort study. We showed that methylation of the Crcp, Calcrl, Esr1 and Nos3 genes is tissue-specific and that methylation in leukocytes was not correlated to that in other tissues. Interestingly, the interindividual variation in methylation differed considerably between genes and tissues. Furthermore we showed that methylation in human leukocytes was similar to that in rat leukocytes in our genes of interest, suggesting that rat may be a good model to study human DNA methylation in tissues that are difficult to obtain. In none of the genes a significant effect of estradiol treatment was observed.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0087616PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3946422PMC
December 2014

Genome-wide association study for radiographic vertebral fractures: a potential role for the 16q24 BMD locus.

Bone 2014 Feb;59:20-7

Vertebral fracture risk is a heritable complex trait. The aim of this study was to identify genetic susceptibility factors for osteoporotic vertebral fractures applying a genome-wide association study (GWAS) approach. The GWAS discovery was based on the Rotterdam Study, a population-based study of elderly Dutch individuals aged > 55 years; and comprising 329 cases and 2666 controls with radiographic scoring (McCloskey–Kanis) and genetic data. Replication of one top-associated SNP was pursued by de-novo genotyping of 15 independent studies across Europe, the United States, and Australia and one Asian study. Radiographic vertebral fracture assessment was performed using McCloskey–Kanis or Genant semi-quantitative definitions. SNPs were analyzed in relation to vertebral fracture using logistic regression models corrected for age and sex. Fixed effects inverse variance and Han–Eskin alternative random effects meta-analyses were applied. Genome-wide significance was set at p < 5 × 10− 8. In the discovery, a SNP (rs11645938) on chromosome 16q24 was associated with the risk for vertebral fractures at p = 4.6 × 10− 8. However, the association was not significant across 5720 cases and 21,791 controls from 14 studies. Fixed-effects meta-analysis summary estimate was 1.06 (95% CI: 0.98–1.14; p = 0.17), displaying high degree of heterogeneity (I2 = 57%; Qhet p = 0.0006). Under Han–Eskin alternative random effects model the summary effect was significant (p = 0.0005). The SNP maps to a region previously found associated with lumbar spine bone mineral density (LS-BMD) in two large meta-analyses from the GEFOS consortium. A false positive association in the GWAS discovery cannot be excluded, yet, the low-powered setting of the discovery and replication settings (appropriate to identify risk effect size > 1.25) may still be consistent with an effect size < 1.10, more of the type expected in complex traits. Larger effort in studies with standardized phenotype definitions is needed to confirm or reject the involvement of this locus on the risk for vertebral fractures.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4102322PMC
February 2014

BMI-associated alleles do not constitute risk alleles for polycystic ovary syndrome independently of BMI: a case-control study.

PLoS One 2014 31;9(1):e87335. Epub 2014 Jan 31.

Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom ; Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, United Kingdom.

Introduction: Polycystic Ovary Syndrome (PCOS) has a strong genetic background and the majority of patients with PCOS have elevated BMI levels. The aim of this study was to determine to which extent BMI-increasing alleles contribute to risk of PCOS when contemporaneous BMI is taken into consideration.

Methods: Patients with PCOS and controls were recruited from the United Kingdom (563 cases and 791 controls) and The Netherlands (510 cases and 2720 controls). Cases and controls were of similar BMI. SNPs mapping to 12 BMI-associated loci which have been extensively replicated across different ethnicities, i.e., BDNF, FAIM2, ETV5, FTO, GNPDA2, KCTD15, MC4R, MTCH2, NEGR1, SEC16B, SH2B1, and TMEM18, were studied in association with PCOS within each cohort using the additive genetic model followed by a combined analysis. A genetic allelic count risk score model was used to determine the risk of PCOS for individuals carrying increasing numbers of BMI-increasing alleles.

Results: None of the genetic variants, including FTO and MC4R, was associated with PCOS independently of BMI in the meta-analysis. Moreover, no differences were observed between cases and controls in the number of BMI-risk alleles present and no overall trend across the risk score groups was observed.

Conclusion: In this combined analysis of over 4,000 BMI-matched individuals from the United Kingdom and the Netherlands, we observed no association of BMI risk alleles with PCOS independent of BMI.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0087335PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3909077PMC
October 2014
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