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1.  Methylation of Migraine-Related Genes in Different Tissues of the Rat 
PLoS ONE  2014;9(3):e87616.
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.
PMCID: PMC3946422  PMID: 24609082
2.  BMI-Associated Alleles Do Not Constitute Risk Alleles for Polycystic Ovary Syndrome Independently of BMI: A Case-Control Study 
PLoS ONE  2014;9(1):e87335.
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.
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.
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.
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.
PMCID: PMC3909077  PMID: 24498077
4.  DNA Methylation of IGF2DMR and H19 Is Associated with Fetal and Infant Growth: The Generation R Study 
PLoS ONE  2013;8(12):e81731.
Changes in epigenetic programming of embryonic growth genes during pregnancy seem to affect fetal growth. Therefore, in a population-based prospective birth cohort in the Netherlands, we examined associations between fetal and infant growth and DNA methylation of IGF2DMR, H19 and MTHFR. For this study, we selected 69 case children born small-for-gestational age (SGA, birth weight <-2SDS) and 471 control children. Fetal growth was assessed with serial ultrasound measurements. Information on birth outcomes was retrieved from medical records. Infant weight was assessed at three and six months. Methylation was assessed in DNA extracted from umbilical cord white blood cells. Analyses were performed using linear mixed models with DNA methylation as dependent variable. The DNA methylation levels of IGF2DMR and H19 in the control group were, median (90% range), 53.6% (44.5–61.6) and 30.0% (25.6–34.2) and in the SGA group 52.0% (43.9–60.9) and 30.5% (23.9–32.9), respectively. The MTHFR region was found to be hypomethylated with limited variability in the control and SGA group, 2.5% (1.4–4.0) and 2.4% (1.5–3.8), respectively. SGA was associated with lower IGF2DMR DNA methylation (β = −1.07, 95% CI −1.93; −0.21, P-value = 0.015), but not with H19 methylation. A weight gain in the first three months after birth was associated with lower IGF2DMR DNA methylation (β = −0.53, 95% CI −0.91; −0.16, P-value = 0.005). Genetic variants in the IGF2/H19 locus were associated with IGF2DMR DNA methylation (P-value<0.05), but not with H19 methylation. Furthermore, our results suggest a possibility of mediation of DNA methylation in the association between the genetic variants and SGA. To conclude, IGF2DMR and H19 DNA methylation is associated with fetal and infant growth.
PMCID: PMC3861253  PMID: 24349121
5.  Epigenetic Profiles in Children with a Neural Tube Defect; A Case-Control Study in Two Populations 
PLoS ONE  2013;8(11):e78462.
Folate deficiency is implicated in the causation of neural tube defects (NTDs). The preventive effect of periconceptional folic acid supplement use is partially explained by the treatment of a deranged folate-dependent one carbon metabolism, which provides methyl groups for DNA-methylation as an epigenetic mechanism. Here, we hypothesize that variations in DNA-methylation of genes implicated in the development of NTDs and embryonic growth are part of the underlying mechanism. In 48 children with a neural tube defect and 62 controls from a Dutch case-control study and 34 children with a neural tube defect and 78 controls from a Texan case-control study, we measured the DNA-methylation levels of imprinted candidate genes (IGF2-DMR, H19, KCNQ1OT1) and non-imprinted genes (the LEKR/CCNL gene region associated with birth weight, and MTHFR and VANGL1 associated with NTD). We used the MassARRAY EpiTYPER assay from Sequenom for the assessment of DNA-methylation. Linear mixed model analysis was used to estimate associations between DNA-methylation levels of the genes and a neural tube defect. In the Dutch study group, but not in the Texan study group we found a significant association between the risk of having an NTD and DNA methylation levels of MTHFR (absolute decrease in methylation of −0.33% in cases, P-value = 0.001), and LEKR/CCNL (absolute increase in methylation: 1.36% in cases, P-value = 0.048), and a borderline significant association for VANGL (absolute increase in methylation: 0.17% in cases, P-value = 0.063). Only the association between MTHFR and NTD-risk remained significant after multiple testing correction. The associations in the Dutch study were not replicated in the Texan study. We conclude that the associations between NTDs and the methylation of the MTHFR gene, and maybe VANGL and LEKKR/CNNL, are in line with previous studies showing polymorphisms in the same genes in association with NTDs and embryonic development, respectively.
PMCID: PMC3818348  PMID: 24223810
6.  Genome-wide association study meta-analysis of chronic widespread pain: evidence for involvement of the 5p15.2 region 
Annals of the rheumatic diseases  2012;72(3):427-436.
Chronic widespread pain (CWP) is a common disorder affecting ~10% of the general population and has an estimated heritability of 48-52%. In the first large-scale genome-wide association study (GWAS) meta-analysis, we aimed to identify common genetic variants associated with CWP.
We conducted a GWAS meta-analysis in 1,308 female CWP cases and 5,791 controls of European descent, and replicated the effects of the genetic variants with suggestive evidence for association in 1,480 CWP cases and 7,989 controls (P<1×10−5). Subsequently, we studied gene expression levels of the nearest genes in two chronic inflammatory pain mouse models, and examined 92 genetic variants previously described associated with pain.
The minor C-allele of rs13361160 on chromosome 5p15.2, located upstream of CCT5 and downstream of FAM173B, was found to be associated with a 30% higher risk of CWP (MAF=43%; OR=1.30, 95%CI=1.19-1.42, P=1.2×10−8). Combined with the replication, we observed a slightly attenuated OR of 1.17 (95%CI=1.10-1.24, P=4.7×10−7) with moderate heterogeneity (I2=28.4%). However, in a sensitivity analysis that only allowed studies with joint-specific pain, the combined association was genome-wide significant (OR=1.23, 95%CI=1.14-1.32, P=3.4×10−8, I2=0%). Expression levels of Cct5 and Fam173b in mice with inflammatory pain were higher in the lumbar spinal cord, not in the lumbar dorsal root ganglions, compared to mice without pain. None of the 92 genetic variants previously described were significantly associated with pain (P>7.7×10−4).
We identified a common genetic variant on chromosome 5p15.2 associated with joint-specific CWP in humans. This work suggests that CCT5 and FAM173B are promising targets in the regulation of pain.
PMCID: PMC3691951  PMID: 22956598
Gene Polymorphism; Fibromyalgia/Pain Syndromes; Epidemiology
7.  Tissue-specific DNA methylation profiles in newborns 
Clinical Epigenetics  2013;5(1):8.
Epidemiological studies demonstrate that foetal growth restriction and low birth weight affect long-term health. Derangements in tissue-specific epigenetic programming of foetal and placental tissues are a suggested underlying mechanism of which DNA methylation is best understood. DNA methylation has been mostly investigated in DNA from white blood cells. To improve baseline understanding of tissue-specific DNA methylation, we examined variation in DNA methylation profiles of the imprinted foetal growth genes IGF2 and H19 in three different tissues from the same newborn obtained at the same time.
We obtained DNA from umbilical cord blood mononuclear cells (MNC; CD34+ and CD34–, n = 6), foetal side of the placenta (n = 5) and umbilical cord Wharton jelly (n = 5). DNA methylation of the IGF2 differentially methylated region (DMR) and H19 DMR was measured using quantitative mass spectrometry. Analysis of variance testing showed no statistical difference between total mean methylation of CD34+ and CD34– MNC. Further comparisons were made with the pooled total MNC fraction. Mean IGF2 DMR methylation of Wharton jelly was 1.3 times higher (P = 0.001) than mean methylation of the pooled MNC. Placental mean methylation was 0.8 times lower (P <0.001) and Wharton jelly 0.9 times lower (P <0.001) than the pooled MNC of H19 DMR.
The total MNC fraction is a rather homogeneous cell population for methylation studies of imprinted genes in umbilical cord blood white blood cells, but may not always reflect the methylation levels of IGF2 and H19 in other organs.
PMCID: PMC3684550  PMID: 23724794
Epigenetics; Umbilical cord blood; Wharton jelly; Placenta; IGF2/H19
8.  A genome-wide association study of early menopause and the combined impact of identified variants 
Human Molecular Genetics  2013;22(7):1465-1472.
Early menopause (EM) affects up to 10% of the female population, reducing reproductive lifespan considerably. Currently, it constitutes the leading cause of infertility in the western world, affecting mainly those women who postpone their first pregnancy beyond the age of 30 years. The genetic aetiology of EM is largely unknown in the majority of cases. We have undertaken a meta-analysis of genome-wide association studies (GWASs) in 3493 EM cases and 13 598 controls from 10 independent studies. No novel genetic variants were discovered, but the 17 variants previously associated with normal age at natural menopause as a quantitative trait (QT) were also associated with EM and primary ovarian insufficiency (POI). Thus, EM has a genetic aetiology which overlaps variation in normal age at menopause and is at least partly explained by the additive effects of the same polygenic variants. The combined effect of the common variants captured by the single nucleotide polymorphism arrays was estimated to account for ∼30% of the variance in EM. The association between the combined 17 variants and the risk of EM was greater than the best validated non-genetic risk factor, smoking.
PMCID: PMC3596848  PMID: 23307926
9.  Meta-analyses identify 13 novel loci associated with age at menopause and highlights DNA repair and immune pathways 
Stolk, Lisette | Perry, John RB | Chasman, Daniel I | He, Chunyan | Mangino, Massimo | Sulem, Patrick | Barbalic, Maja | Broer, Linda | Byrne, Enda M | Ernst, Florian | Esko, Tõnu | Franceschini, Nora | Gudbjartsson, Daniel F | Hottenga, Jouke-Jan | Kraft, Peter | McArdle, Patick F | Porcu, Eleonora | Shin, So-Youn | Smith, Albert V | van Wingerden, Sophie | Zhai, Guangju | Zhuang, Wei V | Albrecht, Eva | Alizadeh, Behrooz Z | Aspelund, Thor | Bandinelli, Stefania | Lauc, Lovorka Barac | Beckmann, Jacques S | Boban, Mladen | Boerwinkle, Eric | Broekmans, Frank J | Burri, Andrea | Campbell, Harry | Chanock, Stephen J | Chen, Constance | Cornelis, Marilyn C | Corre, Tanguy | Coviello, Andrea D | d’Adamo, Pio | Davies, Gail | de Faire, Ulf | de Geus, Eco JC | Deary, Ian J | Dedoussis, George VZ | Deloukas, Panagiotis | Ebrahim, Shah | Eiriksdottir, Gudny | Emilsson, Valur | Eriksson, Johan G | Fauser, Bart CJM | Ferreli, Liana | Ferrucci, Luigi | Fischer, Krista | Folsom, Aaron R | Garcia, Melissa E | Gasparini, Paolo | Gieger, Christian | Glazer, Nicole | Grobbee, Diederick E | Hall, Per | Haller, Toomas | Hankinson, Susan E | Hass, Merli | Hayward, Caroline | Heath, Andrew C | Hofman, Albert | Ingelsson, Erik | Janssens, A Cecile JW | Johnson, Andrew D | Karasik, David | Kardia, Sharon LR | Keyzer, Jules | Kiel, Douglas P | Kolcic, Ivana | Kutalik, Zoltán | Lahti, Jari | Lai, Sandra | Laisk, Triin | Laven, Joop SE | Lawlor, Debbie A | Liu, Jianjun | Lopez, Lorna M | Louwers, Yvonne V | Magnusson, Patrik KE | Marongiu, Mara | Martin, Nicholas G | Klaric, Irena Martinovic | Masciullo, Corrado | McKnight, Barbara | Medland, Sarah E | Melzer, David | Mooser, Vincent | Navarro, Pau | Newman, Anne B | Nyholt, Dale R | Onland-Moret, N. Charlotte | Palotie, Aarno | Paré, Guillaume | Parker, Alex N | Pedersen, Nancy L | Peeters, Petra HM | Pistis, Giorgio | Plump, Andrew S | Polasek, Ozren | Pop, Victor JM | Psaty, Bruce M | Räikkönen, Katri | Rehnberg, Emil | Rotter, Jerome I | Rudan, Igor | Sala, Cinzia | Salumets, Andres | Scuteri, Angelo | Singleton, Andrew | Smith, Jennifer A | Snieder, Harold | Soranzo, Nicole | Stacey, Simon N | Starr, John M | Stathopoulou, Maria G | Stirrups, Kathleen | Stolk, Ronald P | Styrkarsdottir, Unnur | Sun, Yan V | Tenesa, Albert | Thorand, Barbara | Toniolo, Daniela | Tryggvadottir, Laufey | Tsui, Kim | Ulivi, Sheila | van Dam, Rob M | van der Schouw, Yvonne T | van Gils, Carla H | van Nierop, Peter | Vink, Jacqueline M | Visscher, Peter M | Voorhuis, Marlies | Waeber, Gérard | Wallaschofski, Henri | Wichmann, H Erich | Widen, Elisabeth | Gent, Colette JM Wijnands-van | Willemsen, Gonneke | Wilson, James F | Wolffenbuttel, Bruce HR | Wright, Alan F | Yerges-Armstrong, Laura M | Zemunik, Tatijana | Zgaga, Lina | Zillikens, M. Carola | Zygmunt, Marek | Arnold, Alice M | Boomsma, Dorret I | Buring, Julie E. | Crisponi, Laura | Demerath, Ellen W | Gudnason, Vilmundur | Harris, Tamara B | Hu, Frank B | Hunter, David J | Launer, Lenore J | Metspalu, Andres | Montgomery, Grant W | Oostra, Ben A | Ridker, Paul M | Sanna, Serena | Schlessinger, David | Spector, Tim D | Stefansson, Kari | Streeten, Elizabeth A | Thorsteinsdottir, Unnur | Uda, Manuela | Uitterlinden, André G | van Duijn, Cornelia M | Völzke, Henry | Murray, Anna | Murabito, Joanne M | Visser, Jenny A | Lunetta, Kathryn L
Nature Genetics  2012;44(3):260-268.
To identify novel loci for age at natural menopause, we performed a meta-analysis of 22 genome-wide association studies in 38,968 women of European descent, with replication in up to 14,435 women. In addition to four known loci, we identified 13 new age at natural menopause loci (P < 5 × 10−8). The new loci included genes implicated in DNA repair (EXO1, HELQ, UIMC1, FAM175A, FANCI, TLK1, POLG, PRIM1) and immune function (IL11, NLRP11, BAT2). Gene-set enrichment pathway analyses using the full GWAS dataset identified exodeoxyribonuclease, NFκB signalling and mitochondrial dysfunction as biological processes related to timing of menopause.
PMCID: PMC3288642  PMID: 22267201
10.  A Genome-Wide Association Meta-Analysis of Circulating Sex Hormone–Binding Globulin Reveals Multiple Loci Implicated in Sex Steroid Hormone Regulation 
Coviello, Andrea D. | Haring, Robin | Wellons, Melissa | Vaidya, Dhananjay | Lehtimäki, Terho | Keildson, Sarah | Lunetta, Kathryn L. | He, Chunyan | Fornage, Myriam | Lagou, Vasiliki | Mangino, Massimo | Onland-Moret, N. Charlotte | Chen, Brian | Eriksson, Joel | Garcia, Melissa | Liu, Yong Mei | Koster, Annemarie | Lohman, Kurt | Lyytikäinen, Leo-Pekka | Petersen, Ann-Kristin | Prescott, Jennifer | Stolk, Lisette | Vandenput, Liesbeth | Wood, Andrew R. | Zhuang, Wei Vivian | Ruokonen, Aimo | Hartikainen, Anna-Liisa | Pouta, Anneli | Bandinelli, Stefania | Biffar, Reiner | Brabant, Georg | Cox, David G. | Chen, Yuhui | Cummings, Steven | Ferrucci, Luigi | Gunter, Marc J. | Hankinson, Susan E. | Martikainen, Hannu | Hofman, Albert | Homuth, Georg | Illig, Thomas | Jansson, John-Olov | Johnson, Andrew D. | Karasik, David | Karlsson, Magnus | Kettunen, Johannes | Kiel, Douglas P. | Kraft, Peter | Liu, Jingmin | Ljunggren, Östen | Lorentzon, Mattias | Maggio, Marcello | Markus, Marcello R. P. | Mellström, Dan | Miljkovic, Iva | Mirel, Daniel | Nelson, Sarah | Morin Papunen, Laure | Peeters, Petra H. M. | Prokopenko, Inga | Raffel, Leslie | Reincke, Martin | Reiner, Alex P. | Rexrode, Kathryn | Rivadeneira, Fernando | Schwartz, Stephen M. | Siscovick, David | Soranzo, Nicole | Stöckl, Doris | Tworoger, Shelley | Uitterlinden, André G. | van Gils, Carla H. | Vasan, Ramachandran S. | Wichmann, H.-Erich | Zhai, Guangju | Bhasin, Shalender | Bidlingmaier, Martin | Chanock, Stephen J. | De Vivo, Immaculata | Harris, Tamara B. | Hunter, David J. | Kähönen, Mika | Liu, Simin | Ouyang, Pamela | Spector, Tim D. | van der Schouw, Yvonne T. | Viikari, Jorma | Wallaschofski, Henri | McCarthy, Mark I. | Frayling, Timothy M. | Murray, Anna | Franks, Steve | Järvelin, Marjo-Riitta | de Jong, Frank H. | Raitakari, Olli | Teumer, Alexander | Ohlsson, Claes | Murabito, Joanne M. | Perry, John R. B. | Gibson, Greg
PLoS Genetics  2012;8(7):e1002805.
Sex hormone-binding globulin (SHBG) is a glycoprotein responsible for the transport and biologic availability of sex steroid hormones, primarily testosterone and estradiol. SHBG has been associated with chronic diseases including type 2 diabetes (T2D) and with hormone-sensitive cancers such as breast and prostate cancer. We performed a genome-wide association study (GWAS) meta-analysis of 21,791 individuals from 10 epidemiologic studies and validated these findings in 7,046 individuals in an additional six studies. We identified twelve genomic regions (SNPs) associated with circulating SHBG concentrations. Loci near the identified SNPs included SHBG (rs12150660, 17p13.1, p = 1.8×10−106), PRMT6 (rs17496332, 1p13.3, p = 1.4×10−11), GCKR (rs780093, 2p23.3, p = 2.2×10−16), ZBTB10 (rs440837, 8q21.13, p = 3.4×10−09), JMJD1C (rs7910927, 10q21.3, p = 6.1×10−35), SLCO1B1 (rs4149056, 12p12.1, p = 1.9×10−08), NR2F2 (rs8023580, 15q26.2, p = 8.3×10−12), ZNF652 (rs2411984, 17q21.32, p = 3.5×10−14), TDGF3 (rs1573036, Xq22.3, p = 4.1×10−14), LHCGR (rs10454142, 2p16.3, p = 1.3×10−07), BAIAP2L1 (rs3779195, 7q21.3, p = 2.7×10−08), and UGT2B15 (rs293428, 4q13.2, p = 5.5×10−06). These genes encompass multiple biologic pathways, including hepatic function, lipid metabolism, carbohydrate metabolism and T2D, androgen and estrogen receptor function, epigenetic effects, and the biology of sex steroid hormone-responsive cancers including breast and prostate cancer. We found evidence of sex-differentiated genetic influences on SHBG. In a sex-specific GWAS, the loci 4q13.2-UGT2B15 was significant in men only (men p = 2.5×10−08, women p = 0.66, heterogeneity p = 0.003). Additionally, three loci showed strong sex-differentiated effects: 17p13.1-SHBG and Xq22.3-TDGF3 were stronger in men, whereas 8q21.12-ZBTB10 was stronger in women. Conditional analyses identified additional signals at the SHBG gene that together almost double the proportion of variance explained at the locus. Using an independent study of 1,129 individuals, all SNPs identified in the overall or sex-differentiated or conditional analyses explained ∼15.6% and ∼8.4% of the genetic variation of SHBG concentrations in men and women, respectively. The evidence for sex-differentiated effects and allelic heterogeneity highlight the importance of considering these features when estimating complex trait variance.
Author Summary
Sex hormone-binding globulin (SHBG) is the key protein responsible for binding and transporting the sex steroid hormones, testosterone and estradiol, in the circulatory system. SHBG regulates their bioavailability and therefore their effects in the body. SHBG has been linked to chronic diseases including type 2 diabetes and to hormone-sensitive cancers such as breast and prostate cancer. SHBG concentrations are approximately 50% heritable in family studies, suggesting SHBG concentrations are under significant genetic control; yet, little is known about the specific genes that influence SHBG. We conducted a large study of the association of SHBG concentrations with markers in the human genome in ∼22,000 white men and women to determine which loci influence SHBG concentrations. Genes near the identified genomic markers in addition to the SHBG protein coding gene included PRMT6, GCKR, ZBTB10, JMJD1C, SLCO1B1, NR2F2, ZNF652, TDGF3, LHCGR, BAIAP2L1, and UGT2B15. These genes represent a wide range of biologic pathways that may relate to SHBG function and sex steroid hormone biology, including liver function, lipid metabolism, carbohydrate metabolism and type 2 diabetes, and the development and progression of sex steroid hormone-responsive cancers.
PMCID: PMC3400553  PMID: 22829776
11.  A Genome-Wide Association Study identifies a locus on chromosome 7q22 to influence susceptibility for osteoarthritis 
Arthritis and Rheumatism  2010;62(2):499-510.
To identify genes involved in osteoarthritis (OA), the most prevalent form of joint disease, we performed a genome-wide association study (GWAS) in which we tested 500,510 Single Nucelotide Polymorphisms (SNPs) in 1341 OA cases and 3496 Dutch Caucasian controls. SNPs associated with at least two OA-phenotypes were analysed in 14,938 OA cases and approximately 39,000 controls. The C-allele of rs3815148 on chromosome 7q22 (MAF 23%, 172 kb upstream of the GPR22 gene) was consistently associated with a 1.14-fold increased risk (95%CI: 1.09–1.19) for knee- and/or hand-OA (p=8×10−8), and also with a 30% increased risk for knee-OA progression (95%CI: 1.03–1.64, p=0.03). This SNP is in almost complete linkage disequilibrium with rs3757713 (located 68 kb upstream of GPR22) which is associated with GPR22 expression levels in lymphoblast cell lines (p=4×10−12). GPR22 encodes an G-protein coupled receptor with unkown ligand (orphan receptor). Immunohistochemistry experiments showed absence of GPR22 in normal mouse articular cartilage or synovium. However, GPR22 positive chondrocytes were found in the upper layers of the articular cartilage of mouse knee joints that were challenged by in vivo papain treatment or in the presence of interleukin-1 driven inflammation. GRP22 positive chondrocyte-like cells were also found in osteophytes in instability-induced OA. In addition, GPR22 is also present in areas of the brain involved in locomotor function. Our findings reveal a novel common variant on chromosome 7q22 to influence susceptibility for prevalence and progression of OA.
PMCID: PMC3354739  PMID: 20112360
12.  Replication of Association of a Novel Insulin Receptor Gene Polymorphism with Polycystic Ovary Syndrome 
Fertility and sterility  2011;95(5):1736-1741.e11.
To evaluate association with polycystic ovary syndrome (PCOS) of 295 variants in 39 genes central to metabolic insulin signaling and glycogen synthase kinase-3β (GSK-3β) regulation, followed by replication efforts.
Case-control association study, with discovery and replication cohorts.
Subjects were recruited from reproductive endocrinology clinics, controls were recruited from communities surrounding the University of Alabama at Birmingham and Erasmus Medical Center.
273 cases with PCOS and 173 controls in the discovery cohort; 526 cases and 3585 controls in the replication cohort. All subjects were Caucasian.
Phenotypic and genotypic assessment.
Main Outcome Measures
295 SNPs, PCOS status.
Several SNPs were associated with PCOS in the discovery cohort. Four insulin receptor (INSR) SNPs and three insulin receptor substrate 2 (IRS2) SNPs associated with PCOS (P<0.05) were genotyped in the replication cohort. One INSR SNP (rs2252673) replicated association with PCOS. The minor allele conferred increased odds of PCOS in both cohorts, independent of body mass index (BMI).
A pathway-based, tagging SNP approach allowed us to identify novel INSR SNPs associated with PCOS, one of which confirmed association in a large replication cohort.
PMCID: PMC3062664  PMID: 21300347
PCOS; INSR; replication; SNP
13.  Reproductive aging-associated common genetic variants and the risk of breast cancer 
A younger age at menarche and an older age at menopause are well established risk factors for breast cancer. Recent genome-wide association studies have identified several novel genetic loci associated with these two traits. However, the association between these loci and breast cancer risk is unknown.
In this study, we investigated 19 and 17 newly identified single nucleotide polymorphisms (SNPs) from the ReproGen Consortium that have been associated with age at menarche and age at natural menopause, respectively, and assessed their associations with breast cancer risk in 6 population-based studies among up to 3,683 breast cancer cases and 34,174 controls in white women of European ancestry. In addition, we used these SNPs to calculate genetic risk scores (GRSs) based on their associations with each trait.
After adjusting for age and potential population stratification, two age at menarche associated SNPs (rs1079866 and rs7821178) and one age at natural menopause associated SNP (rs2517388) were associated with breast cancer risk (p values, 0.003, 0.009 and 0.023, respectively). The odds ratios for breast cancer corresponding to per-risk-allele were 1.14 (95% CI, 1.05 to 1.24), 1.08 (95% CI, 1.02 to 1.15) and 1.10 (95% CI, 1.01 to 1.20), respectively, and were in the direction predicted by their associations with age at menarche or age at natural menopause. These associations did not appear to be attenuated by further controlling for self-reported age at menarche, age at natural menopause, or known breast cancer susceptibility loci. Although we did not observe a statistically significant association between any GRS for reproductive aging and breast cancer risk, the 4th and 5th highest quintiles of the younger age at menarche GRS had odds ratios of 1.14 (95% CI, 1.01 to 1.28) and 1.13 (95% CI, 1.00 to 1.27), respectively, compared to the lowest quintile.
Our study suggests that three genetic variants, independent of their associations with age at menarche or age at natural menopause, were associated with breast cancer risk and may contribute modestly to breast cancer risk prediction; however, the combination of the 19 age at menarche or the 17 age at natural menopause associated SNPs did not appear to be useful for identifying a high risk subgroup for breast cancer.
PMCID: PMC3446388  PMID: 22433456
14.  Thirty new loci for age at menarche identified by a meta-analysis of genome-wide association studies 
Elks, Cathy E. | Perry, John R.B. | Sulem, Patrick | Chasman, Daniel I. | Franceschini, Nora | He, Chunyan | Lunetta, Kathryn L. | Visser, Jenny A. | Byrne, Enda M. | Cousminer, Diana L. | Gudbjartsson, Daniel F. | Esko, Tõnu | Feenstra, Bjarke | Hottenga, Jouke-Jan | Koller, Daniel L. | Kutalik, Zoltán | Lin, Peng | Mangino, Massimo | Marongiu, Mara | McArdle, Patrick F. | Smith, Albert V. | Stolk, Lisette | van Wingerden, Sophie W. | Zhao, Jing Hua | Albrecht, Eva | Corre, Tanguy | Ingelsson, Erik | Hayward, Caroline | Magnusson, Patrik K.E. | Smith, Erin N. | Ulivi, Shelia | Warrington, Nicole M. | Zgaga, Lina | Alavere, Helen | Amin, Najaf | Aspelund, Thor | Bandinelli, Stefania | Barroso, Ines | Berenson, Gerald S. | Bergmann, Sven | Blackburn, Hannah | Boerwinkle, Eric | Buring, Julie E. | Busonero, Fabio | Campbell, Harry | Chanock, Stephen J. | Chen, Wei | Cornelis, Marilyn C. | Couper, David | Coviello, Andrea D. | d’Adamo, Pio | de Faire, Ulf | de Geus, Eco J.C. | Deloukas, Panos | Döring, Angela | Smith, George Davey | Easton, Douglas F. | Eiriksdottir, Gudny | Emilsson, Valur | Eriksson, Johan | Ferrucci, Luigi | Folsom, Aaron R. | Foroud, Tatiana | Garcia, Melissa | Gasparini, Paolo | Geller, Frank | Gieger, Christian | Gudnason, Vilmundur | Hall, Per | Hankinson, Susan E. | Ferreli, Liana | Heath, Andrew C. | Hernandez, Dena G. | Hofman, Albert | Hu, Frank B. | Illig, Thomas | Järvelin, Marjo-Riitta | Johnson, Andrew D. | Karasik, David | Khaw, Kay-Tee | Kiel, Douglas P. | Kilpeläinen, Tuomas O. | Kolcic, Ivana | Kraft, Peter | Launer, Lenore J. | Laven, Joop S.E. | Li, Shengxu | Liu, Jianjun | Levy, Daniel | Martin, Nicholas G. | McArdle, Wendy L. | Melbye, Mads | Mooser, Vincent | Murray, Jeffrey C. | Murray, Sarah S. | Nalls, Michael A. | Navarro, Pau | Nelis, Mari | Ness, Andrew R. | Northstone, Kate | Oostra, Ben A. | Peacock, Munro | Palmer, Lyle J. | Palotie, Aarno | Paré, Guillaume | Parker, Alex N. | Pedersen, Nancy L. | Peltonen, Leena | Pennell, Craig E. | Pharoah, Paul | Polasek, Ozren | Plump, Andrew S. | Pouta, Anneli | Porcu, Eleonora | Rafnar, Thorunn | Rice, John P. | Ring, Susan M. | Rivadeneira, Fernando | Rudan, Igor | Sala, Cinzia | Salomaa, Veikko | Sanna, Serena | Schlessinger, David | Schork, Nicholas J. | Scuteri, Angelo | Segrè, Ayellet V. | Shuldiner, Alan R. | Soranzo, Nicole | Sovio, Ulla | Srinivasan, Sathanur R. | Strachan, David P. | Tammesoo, Mar-Liis | Tikkanen, Emmi | Toniolo, Daniela | Tsui, Kim | Tryggvadottir, Laufey | Tyrer, Jonathon | Uda, Manuela | van Dam, Rob M. | van Meurs, Joyve B.J. | Vollenweider, Peter | Waeber, Gerard | Wareham, Nicholas J. | Waterworth, Dawn M. | Weedon, Michael N. | Wichmann, H. Erich | Willemsen, Gonneke | Wilson, James F. | Wright, Alan F. | Young, Lauren | Zhai, Guangju | Zhuang, Wei Vivian | Bierut, Laura J. | Boomsma, Dorret I. | Boyd, Heather A. | Crisponi, Laura | Demerath, Ellen W. | van Duijn, Cornelia M. | Econs, Michael J. | Harris, Tamara B. | Hunter, David J. | Loos, Ruth J.F. | Metspalu, Andres | Montgomery, Grant W. | Ridker, Paul M. | Spector, Tim D. | Streeten, Elizabeth A. | Stefansson, Kari | Thorsteinsdottir, Unnur | Uitterlinden, André G. | Widen, Elisabeth | Murabito, Joanne M. | Ong, Ken K. | Murray, Anna
Nature genetics  2010;42(12):1077-1085.
To identify loci for age at menarche, we performed a meta-analysis of 32 genome-wide association studies in 87,802 women of European descent, with replication in up to 14,731 women. In addition to the known loci at LIN28B (P=5.4×10−60) and 9q31.2 (P=2.2×10−33), we identified 30 novel menarche loci (all P<5×10−8) and found suggestive evidence for a further 10 loci (P<1.9×10−6). New loci included four previously associated with BMI (in/near FTO, SEC16B, TRA2B and TMEM18), three in/near other genes implicated in energy homeostasis (BSX, CRTC1, and MCHR2), and three in/near genes implicated in hormonal regulation (INHBA, PCSK2 and RXRG). Ingenuity and MAGENTA pathway analyses identified coenzyme A and fatty acid biosynthesis as biological processes related to menarche timing.
PMCID: PMC3140055  PMID: 21102462
15.  Genetic Determinants of Serum Testosterone Concentrations in Men 
PLoS Genetics  2011;7(10):e1002313.
Testosterone concentrations in men are associated with cardiovascular morbidity, osteoporosis, and mortality and are affected by age, smoking, and obesity. Because of serum testosterone's high heritability, we performed a meta-analysis of genome-wide association data in 8,938 men from seven cohorts and followed up the genome-wide significant findings in one in silico (n = 871) and two de novo replication cohorts (n = 4,620) to identify genetic loci significantly associated with serum testosterone concentration in men. All these loci were also associated with low serum testosterone concentration defined as <300 ng/dl. Two single-nucleotide polymorphisms at the sex hormone-binding globulin (SHBG) locus (17p13-p12) were identified as independently associated with serum testosterone concentration (rs12150660, p = 1.2×10−41 and rs6258, p = 2.3×10−22). Subjects with ≥3 risk alleles of these variants had 6.5-fold higher risk of having low serum testosterone than subjects with no risk allele. The rs5934505 polymorphism near FAM9B on the X chromosome was also associated with testosterone concentrations (p = 5.6×10−16). The rs6258 polymorphism in exon 4 of SHBG affected SHBG's affinity for binding testosterone and the measured free testosterone fraction (p<0.01). Genetic variants in the SHBG locus and on the X chromosome are associated with a substantial variation in testosterone concentrations and increased risk of low testosterone. rs6258 is the first reported SHBG polymorphism, which affects testosterone binding to SHBG and the free testosterone fraction and could therefore influence the calculation of free testosterone using law-of-mass-action equation.
Author Summary
Testosterone is the most important testicular androgen in men. Low serum testosterone concentrations are associated with cardiovascular morbidity, metabolic syndrome, type 2 diabetes mellitus, atherosclerosis, osteoporosis, sarcopenia, and increased mortality risk. Thus, there is growing evidence that serum testosterone is a valuable biomarker of men's overall health status. Studies in male twins indicate that there is a strong heritability of serum testosterone. Here we perform a large-scale genome-wide association study to examine the effects of common genetic variants on serum testosterone concentrations. By examining 14,429 men, we show that genetic variants in the sex hormone-binding globulin (SHBG) locus and on the X chromosome are associated with a substantial variation in serum testosterone concentrations and increased risk of low testosterone. The reported associations may now be used in order to better understand the functional background of recently identified disease associations related to low testosterone. Importantly, we identified the first known genetic variant, which affects SHBG's affinity for binding testosterone and the free testosterone fraction and could therefore influence the calculation of free testosterone. This finding suggests that individual-based SHBG-testosterone affinity constants are required depending on the genotype of this single-nucleotide polymorphism.
PMCID: PMC3188559  PMID: 21998597
16.  Eight Common Genetic Variants Associated with Serum DHEAS Levels Suggest a Key Role in Ageing Mechanisms 
PLoS Genetics  2011;7(4):e1002025.
Dehydroepiandrosterone sulphate (DHEAS) is the most abundant circulating steroid secreted by adrenal glands—yet its function is unknown. Its serum concentration declines significantly with increasing age, which has led to speculation that a relative DHEAS deficiency may contribute to the development of common age-related diseases or diminished longevity. We conducted a meta-analysis of genome-wide association data with 14,846 individuals and identified eight independent common SNPs associated with serum DHEAS concentrations. Genes at or near the identified loci include ZKSCAN5 (rs11761528; p = 3.15×10−36), SULT2A1 (rs2637125; p = 2.61×10−19), ARPC1A (rs740160; p = 1.56×10−16), TRIM4 (rs17277546; p = 4.50×10−11), BMF (rs7181230; p = 5.44×10−11), HHEX (rs2497306; p = 4.64×10−9), BCL2L11 (rs6738028; p = 1.72×10−8), and CYP2C9 (rs2185570; p = 2.29×10−8). These genes are associated with type 2 diabetes, lymphoma, actin filament assembly, drug and xenobiotic metabolism, and zinc finger proteins. Several SNPs were associated with changes in gene expression levels, and the related genes are connected to biological pathways linking DHEAS with ageing. This study provides much needed insight into the function of DHEAS.
Author Summary
Dehydroepiandrosterone sulphate (DHEAS), mainly secreted by the adrenal gland, is the most abundant circulating steroid in humans. It shows a significant physiological decline after the age of 25 and diminishes about 95% by the age of 85 years, which has led to speculation that a relative DHEAS deficiency may contribute to the development of common age-related diseases or diminished longevity. Twin- and family-based studies have shown that there is a substantial genetic effect with heritability estimate of 60%, but no specific genes regulating serum DHEAS concentration have been identified to date. Here we take advantage of recent technical and methodological advances to examine the effects of common genetic variants on serum DHEAS concentrations. By examining 14,846 Caucasian individuals, we show that eight common genetic variants are associated with serum DHEAS concentrations. Genes at or near these genetic variants include BCL2L11, ARPC1A, ZKSCAN5, TRIM4, HHEX, CYP2C9, BMF, and SULT2A1. These genes have various associations with steroid hormone metabolism—co-morbidities of ageing including type 2 diabetes, lymphoma, actin filament assembly, drug and xenobiotic metabolism, and zinc finger proteins—suggesting a wider functional role for DHEAS than previously thought.
PMCID: PMC3077384  PMID: 21533175
17.  Loci at chromosomes 13, 19 and 20 influence age at natural menopause 
Nature genetics  2009;41(6):645-647.
We conducted a genome-wide association study for age at natural menopause in 2,979 European women and identified six SNPs in three loci associated with age at natural menopause: chromosome 19q13.4 (rs1172822; −0.4 year per T allele (39%); P = 6.3 × 10−11), chromosome 20p12.3 (rs236114; +0.5 year per A allele (21%); P = 9.7 × 10−11) and chromosome 13q34 (rs7333181; +0.5 year per A allele (12%); P = 2.5 × 10−8). These common genetic variants regulate timing of ovarian aging, an important risk factor for breast cancer, osteoporosis and cardiovascular disease.
PMCID: PMC3000545  PMID: 19448619
18.  Common genetic variation in the Estrogen Receptor Beta (ESR2) gene and osteoarthritis: results of a meta-analysis 
BMC Medical Genetics  2010;11:164.
The objective of this study was to examine the relationship between common genetic variation of the ESR2 gene and osteoarthritis.
In the discovery study, the Rotterdam Study-I, 7 single nucleotide polymorphisms (SNPs) were genotyped and tested for association with hip (284 cases, 2772 controls), knee (665 cases, 2075 controls), and hand OA (874 cases, 2184 controls) using an additive model. In the replication stage one SNP (rs1256031) was tested in an additional 2080 hip, 1318 knee and 557 hand OA cases and 4001, 2631 and 1699 controls respectively. Fixed- and random-effects meta-analyses were performed over the complete dataset including 2364 hip, 1983 knee and 1431 hand OA cases and approximately 6000 controls.
The C allele of rs1256031 was associated with a 36% increased odds of hip OA in women of the Rotterdam Study-I (OR 1.36, 95% CI 1.08-1.70, p = 0.009). Haplotype analysis and analysis of knee- and hand OA did not give additional information. With the replication studies, the meta-analysis did not show a significant effect of this SNP on hip OA in the total population (OR 1.06, 95% CI 0.99-1.15, p = 0.10). Stratification according to gender did not change the results. In this study, we had 80% power to detect an odds ratio of at least 1.14 for hip OA (α = 0.05).
This study showed that common genetic variation in the ESR2 gene is not likely to influence the risk of osteoarthritis with effects smaller than a 13% increase.
PMCID: PMC2997092  PMID: 21080949
19.  Meta-analysis of genome-wide association data identifies two loci influencing age at menarche 
Nature genetics  2009;41(6):648-650.
We conducted a meta-analysis of genome-wide association data to detect genes influencing age at menarche in 17,510 women. The strongest signal was at 9q31.2 (P = 1.7 × 10−9), where the nearest genes include TMEM38B, FKTN, FSD1L, TAL2 and ZNF462. The next best signal was near the LIN28B gene (rs7759938; P = 7.0 × 10−9), which also influences adult height. We provide the first evidence for common genetic variants influencing female sexual maturation.
PMCID: PMC2942986  PMID: 19448620
20.  A genome-wide association study of northwestern Europeans involves the C-type natriuretic peptide signaling pathway in the etiology of human height variation 
Human Molecular Genetics  2009;18(18):3516-3524.
Northwestern Europeans are among the tallest of human populations. The increase in body height in these people appears to have reached a plateau, suggesting the ubiquitous presence of an optimal environment in which genetic factors may have exerted a particularly strong influence on human growth. Therefore, we performed a genome-wide association study (GWAS) of body height using 2.2 million markers in 10 074 individuals from three Dutch and one German population-based cohorts. Upon genotyping, the 12 most significantly height-associated single nucleotide polymorphisms (SNPs) from this GWAS in 6912 additional individuals of Dutch and Swedish origin, a genetic variant (rs6717918) on chromosome 2q37.1 was found to be associated with height at a genome-wide significance level (Pcombined = 3.4 × 10−9). Notably, a second SNP (rs6718438) located ∼450 bp away and in strong LD (r2 = 0.77) with rs6717918 was previously found to be suggestive of a height association in 29 820 individuals of mainly northwestern European ancestry, and the over-expression of a nearby natriuretic peptide precursor type C (NPPC) gene, has been associated with overgrowth and skeletal anomalies. We also found a SNP (rs10472828) located on 5p14 near the natriuretic peptide receptor 3 (NPR3) gene, encoding a receptor of the NPPC ligand, to be associated with body height (Pcombined = 2.1 × 10−7). Taken together, these results suggest that variation in the C-type natriuretic peptide signaling pathway, involving the NPPC and NPR3 genes, plays an important role in determining human body height.
PMCID: PMC2729669  PMID: 19570815
21.  Meta-Analysis of Genome-Wide Scans for Human Adult Stature Identifies Novel Loci and Associations with Measures of Skeletal Frame Size 
PLoS Genetics  2009;5(4):e1000445.
Recent genome-wide (GW) scans have identified several independent loci affecting human stature, but their contribution through the different skeletal components of height is still poorly understood. We carried out a genome-wide scan in 12,611 participants, followed by replication in an additional 7,187 individuals, and identified 17 genomic regions with GW-significant association with height. Of these, two are entirely novel (rs11809207 in CATSPER4, combined P-value = 6.1×10−8 and rs910316 in TMED10, P-value = 1.4×10−7) and two had previously been described with weak statistical support (rs10472828 in NPR3, P-value = 3×10−7 and rs849141 in JAZF1, P-value = 3.2×10−11). One locus (rs1182188 at GNA12) identifies the first height eQTL. We also assessed the contribution of height loci to the upper- (trunk) and lower-body (hip axis and femur) skeletal components of height. We find evidence for several loci associated with trunk length (including rs6570507 in GPR126, P-value = 4×10−5 and rs6817306 in LCORL, P-value = 4×10−4), hip axis length (including rs6830062 at LCORL, P-value = 4.8×10−4 and rs4911494 at UQCC, P-value = 1.9×10−4), and femur length (including rs710841 at PRKG2, P-value = 2.4×10−5 and rs10946808 at HIST1H1D, P-value = 6.4×10−6). Finally, we used conditional analyses to explore a possible differential contribution of the height loci to these different skeletal size measurements. In addition to validating four novel loci controlling adult stature, our study represents the first effort to assess the contribution of genetic loci to three skeletal components of height. Further statistical tests in larger numbers of individuals will be required to verify if the height loci affect height preferentially through these subcomponents of height.
Author Summary
The first genetic association studies of adult height have confirmed a role of many common variants in influencing human height, but to date, the genetic basis of differences between different skeletal components of height have not been addressed. Here, we take advantage of recent technical and methodological advances to examine the role of common genetic variants on both height and skeletal components of height. By examining nearly 20,000 individuals from the UK and the Netherlands, we provide statistically significant evidence that 17 genomic regions are associated with height, including four novel regions. We also examine, for the first time, the association of these 17 regions with skeletal size measurements of spine, femur, and hip axis length, a measurement of hip geometry known to influence the risk of osteoporotic fractures. We find that some height loci are also associated with these skeletal components, although further statistical tests will be required to verify if these genetic variants act differentially on the individual skeletal measurements. The knowledge generated by this and other studies will not only inform the genetics of human quantitative variation, but will also lead to the potential discovery of many medically important polymorphisms.
PMCID: PMC2661236  PMID: 19343178

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