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The CODATwins Project: The Current Status and Recent Findings of COllaborative Project of Development of Anthropometrical Measures in Twins
- K. Silventoinen, A. Jelenkovic, Y. Yokoyama, R. Sund, M. Sugawara, M. Tanaka, S. Matsumoto, L. H. Bogl, D. L. Freitas, J. A. Maia, J. v. B. Hjelmborg, S. Aaltonen, M. Piirtola, A. Latvala, L. Calais-Ferreira, V. C. Oliveira, P. H. Ferreira, F. Ji, F. Ning, Z. Pang, J. R. Ordoñana, J. F. Sánchez-Romera, L. Colodro-Conde, S. A. Burt, K. L. Klump, N. G. Martin, S. E. Medland, G. W. Montgomery, C. Kandler, T. A. McAdams, T. C. Eley, A. M. Gregory, K. J. Saudino, L. Dubois, M. Boivin, M. Brendgen, G. Dionne, F. Vitaro, A. D. Tarnoki, D. L. Tarnoki, C. M. A. Haworth, R. Plomin, S. Y. Öncel, F. Aliev, E. Medda, L. Nisticò, V. Toccaceli, J. M. Craig, R. Saffery, S. H. Siribaddana, M. Hotopf, A. Sumathipala, F. Rijsdijk, H.-U. Jeong, T. Spector, M. Mangino, G. Lachance, M. Gatz, D. A. Butler, W. Gao, C. Yu, L. Li, G. Bayasgalan, D. Narandalai, K. P. Harden, E. M. Tucker-Drob, K. Christensen, A. Skytthe, K. O. Kyvik, C. A. Derom, R. F. Vlietinck, R. J. F. Loos, W. Cozen, A. E. Hwang, T. M. Mack, M. He, X. Ding, J. L. Silberg, H. H. Maes, T. L. Cutler, J. L. Hopper, P. K. E. Magnusson, N. L. Pedersen, A. K. Dahl Aslan, L. A. Baker, C. Tuvblad, M. Bjerregaard-Andersen, H. Beck-Nielsen, M. Sodemann, V. Ullemar, C. Almqvist, Q. Tan, D. Zhang, G. E. Swan, R. Krasnow, K. L. Jang, A. Knafo-Noam, D. Mankuta, L. Abramson, P. Lichtenstein, R. F. Krueger, M. McGue, S. Pahlen, P. Tynelius, F. Rasmussen, G. E. Duncan, D. Buchwald, R. P. Corley, B. M. Huibregtse, T. L. Nelson, K. E. Whitfield, C. E. Franz, W. S. Kremen, M. J. Lyons, S. Ooki, I. Brandt, T. S. Nilsen, J. R. Harris, J. Sung, H. A. Park, J. Lee, S. J. Lee, G. Willemsen, M. Bartels, C. E. M. van Beijsterveldt, C. H. Llewellyn, A. Fisher, E. Rebato, A. Busjahn, R. Tomizawa, F. Inui, M. Watanabe, C. Honda, N. Sakai, Y.-M. Hur, T. I. A. Sørensen, D. I. Boomsma, J. Kaprio
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- Journal:
- Twin Research and Human Genetics / Volume 22 / Issue 6 / December 2019
- Published online by Cambridge University Press:
- 31 July 2019, pp. 800-808
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The COllaborative project of Development of Anthropometrical measures in Twins (CODATwins) project is a large international collaborative effort to analyze individual-level phenotype data from twins in multiple cohorts from different environments. The main objective is to study factors that modify genetic and environmental variation of height, body mass index (BMI, kg/m2) and size at birth, and additionally to address other research questions such as long-term consequences of birth size. The project started in 2013 and is open to all twin projects in the world having height and weight measures on twins with information on zygosity. Thus far, 54 twin projects from 24 countries have provided individual-level data. The CODATwins database includes 489,981 twin individuals (228,635 complete twin pairs). Since many twin cohorts have collected longitudinal data, there is a total of 1,049,785 height and weight observations. For many cohorts, we also have information on birth weight and length, own smoking behavior and own or parental education. We found that the heritability estimates of height and BMI systematically changed from infancy to old age. Remarkably, only minor differences in the heritability estimates were found across cultural–geographic regions, measurement time and birth cohort for height and BMI. In addition to genetic epidemiological studies, we looked at associations of height and BMI with education, birth weight and smoking status. Within-family analyses examined differences within same-sex and opposite-sex dizygotic twins in birth size and later development. The CODATwins project demonstrates the feasibility and value of international collaboration to address gene-by-exposure interactions that require large sample sizes and address the effects of different exposures across time, geographical regions and socioeconomic status.
Education in Twins and Their Parents Across Birth Cohorts Over 100 years: An Individual-Level Pooled Analysis of 42-Twin Cohorts
- Karri Silventoinen, Aline Jelenkovic, Antti Latvala, Reijo Sund, Yoshie Yokoyama, Vilhelmina Ullemar, Catarina Almqvist, Catherine A. Derom, Robert F. Vlietinck, Ruth J. F. Loos, Christian Kandler, Chika Honda, Fujio Inui, Yoshinori Iwatani, Mikio Watanabe, Esther Rebato, Maria A. Stazi, Corrado Fagnani, Sonia Brescianini, Yoon-Mi Hur, Hoe-Uk Jeong, Tessa L. Cutler, John L. Hopper, Andreas Busjahn, Kimberly J. Saudino, Fuling Ji, Feng Ning, Zengchang Pang, Richard J. Rose, Markku Koskenvuo, Kauko Heikkilä, Wendy Cozen, Amie E. Hwang, Thomas M. Mack, Sisira H. Siribaddana, Matthew Hotopf, Athula Sumathipala, Fruhling Rijsdijk, Joohon Sung, Jina Kim, Jooyeon Lee, Sooji Lee, Tracy L. Nelson, Keith E. Whitfield, Qihua Tan, Dongfeng Zhang, Clare H. Llewellyn, Abigail Fisher, S. Alexandra Burt, Kelly L. Klump, Ariel Knafo-Noam, David Mankuta, Lior Abramson, Sarah E. Medland, Nicholas G. Martin, Grant W. Montgomery, Patrik K. E. Magnusson, Nancy L. Pedersen, Anna K. Dahl Aslan, Robin P. Corley, Brooke M. Huibregtse, Sevgi Y. Öncel, Fazil Aliev, Robert F. Krueger, Matt McGue, Shandell Pahlen, Gonneke Willemsen, Meike Bartels, Catharina E. M. van Beijsterveldt, Judy L. Silberg, Lindon J. Eaves, Hermine H. Maes, Jennifer R. Harris, Ingunn Brandt, Thomas S. Nilsen, Finn Rasmussen, Per Tynelius, Laura A. Baker, Catherine Tuvblad, Juan R. Ordoñana, Juan F. Sánchez-Romera, Lucia Colodro-Conde, Margaret Gatz, David A. Butler, Paul Lichtenstein, Jack H. Goldberg, K. Paige Harden, Elliot M. Tucker-Drob, Glen E. Duncan, Dedra Buchwald, Adam D. Tarnoki, David L. Tarnoki, Carol E. Franz, William S. Kremen, Michael J. Lyons, José A. Maia, Duarte L. Freitas, Eric Turkheimer, Thorkild I. A. Sørensen, Dorret I. Boomsma, Jaakko Kaprio
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- Journal:
- Twin Research and Human Genetics / Volume 20 / Issue 5 / October 2017
- Published online by Cambridge University Press:
- 04 October 2017, pp. 395-405
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Whether monozygotic (MZ) and dizygotic (DZ) twins differ from each other in a variety of phenotypes is important for genetic twin modeling and for inferences made from twin studies in general. We analyzed whether there were differences in individual, maternal and paternal education between MZ and DZ twins in a large pooled dataset. Information was gathered on individual education for 218,362 adult twins from 27 twin cohorts (53% females; 39% MZ twins), and on maternal and paternal education for 147,315 and 143,056 twins respectively, from 28 twin cohorts (52% females; 38% MZ twins). Together, we had information on individual or parental education from 42 twin cohorts representing 19 countries. The original education classifications were transformed to education years and analyzed using linear regression models. Overall, MZ males had 0.26 (95% CI [0.21, 0.31]) years and MZ females 0.17 (95% CI [0.12, 0.21]) years longer education than DZ twins. The zygosity difference became smaller in more recent birth cohorts for both males and females. Parental education was somewhat longer for fathers of DZ twins in cohorts born in 1990–1999 (0.16 years, 95% CI [0.08, 0.25]) and 2000 or later (0.11 years, 95% CI [0.00, 0.22]), compared with fathers of MZ twins. The results show that the years of both individual and parental education are largely similar in MZ and DZ twins. We suggest that the socio-economic differences between MZ and DZ twins are so small that inferences based upon genetic modeling of twin data are not affected.
Twin's Birth-Order Differences in Height and Body Mass Index From Birth to Old Age: A Pooled Study of 26 Twin Cohorts Participating in the CODATwins Project
- Yoshie Yokoyama, Aline Jelenkovic, Reijo Sund, Joohon Sung, John L. Hopper, Syuichi Ooki, Kauko Heikkilä, Sari Aaltonen, Adam D. Tarnoki, David L. Tarnoki, Gonneke Willemsen, Meike Bartels, Toos C. E. M. van Beijsterveldt, Kimberly J. Saudino, Tessa L. Cutler, Tracy L. Nelson, Keith E. Whitfield, Jane Wardle, Clare H. Llewellyn, Abigail Fisher, Mingguang He, Xiaohu Ding, Morten Bjerregaard-Andersen, Henning Beck-Nielsen, Morten Sodemann, Yun-Mi Song, Sarah Yang, Kayoung Lee, Hoe-Uk Jeong, Ariel Knafo-Noam, David Mankuta, Lior Abramson, S. Alexandra Burt, Kelly L. Klump, Juan R. Ordoñana, Juan F. Sánchez-Romera, Lucia Colodro-Conde, Jennifer R. Harris, Ingunn Brandt, Thomas Sevenius Nilsen, Jeffrey M. Craig, Richard Saffery, Fuling Ji, Feng Ning, Zengchang Pang, Lise Dubois, Michel Boivin, Mara Brendgen, Ginette Dionne, Frank Vitaro, Nicholas G. Martin, Sarah E. Medland, Grant W. Montgomery, Patrik K. E. Magnusson, Nancy L. Pedersen, Anna K. Dahl Aslan, Per Tynelius, Claire M. A. Haworth, Robert Plomin, Esther Rebato, Richard J. Rose, Jack H. Goldberg, Finn Rasmussen, Yoon-Mi Hur, Thorkild I. A. Sørensen, Dorret I. Boomsma, Jaakko Kaprio, Karri Silventoinen
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- Journal:
- Twin Research and Human Genetics / Volume 19 / Issue 2 / April 2016
- Published online by Cambridge University Press:
- 09 March 2016, pp. 112-124
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We analyzed birth order differences in means and variances of height and body mass index (BMI) in monozygotic (MZ) and dizygotic (DZ) twins from infancy to old age. The data were derived from the international CODATwins database. The total number of height and BMI measures from 0.5 to 79.5 years of age was 397,466. As expected, first-born twins had greater birth weight than second-born twins. With respect to height, first-born twins were slightly taller than second-born twins in childhood. After adjusting the results for birth weight, the birth order differences decreased and were no longer statistically significant. First-born twins had greater BMI than the second-born twins over childhood and adolescence. After adjusting the results for birth weight, birth order was still associated with BMI until 12 years of age. No interaction effect between birth order and zygosity was found. Only limited evidence was found that birth order influenced variances of height or BMI. The results were similar among boys and girls and also in MZ and DZ twins. Overall, the differences in height and BMI between first- and second-born twins were modest even in early childhood, while adjustment for birth weight reduced the birth order differences but did not remove them for BMI.
Zygosity Differences in Height and Body Mass Index of Twins From Infancy to Old Age: A Study of the CODATwins Project
- Aline Jelenkovic, Yoshie Yokoyama, Reijo Sund, Chika Honda, Leonie H Bogl, Sari Aaltonen, Fuling Ji, Feng Ning, Zengchang Pang, Juan R. Ordoñana, Juan F. Sánchez-Romera, Lucia Colodro-Conde, S. Alexandra Burt, Kelly L. Klump, Sarah E. Medland, Grant W. Montgomery, Christian Kandler, Tom A. McAdams, Thalia C. Eley, Alice M. Gregory, Kimberly J. Saudino, Lise Dubois, Michel Boivin, Adam D. Tarnoki, David L. Tarnoki, Claire M. A. Haworth, Robert Plomin, Sevgi Y. Öncel, Fazil Aliev, Maria A. Stazi, Corrado Fagnani, Cristina D’Ippolito, Jeffrey M. Craig, Richard Saffery, Sisira H. Siribaddana, Matthew Hotopf, Athula Sumathipala, Fruhling Rijsdijk, Timothy Spector, Massimo Mangino, Genevieve Lachance, Margaret Gatz, David A. Butler, Gombojav Bayasgalan, Danshiitsoodol Narandalai, Duarte L Freitas, José Antonio Maia, K. Paige Harden, Elliot M. Tucker-Drob, Bia Kim, Youngsook Chong, Changhee Hong, Hyun Jung Shin, Kaare Christensen, Axel Skytthe, Kirsten O. Kyvik, Catherine A. Derom, Robert F. Vlietinck, Ruth J. F. Loos, Wendy Cozen, Amie E. Hwang, Thomas M. Mack, Mingguang He, Xiaohu Ding, Billy Chang, Judy L. Silberg, Lindon J. Eaves, Hermine H. Maes, Tessa L. Cutler, John L. Hopper, Kelly Aujard, Patrik K. E. Magnusson, Nancy L. Pedersen, Anna K. Dahl Aslan, Yun-Mi Song, Sarah Yang, Kayoung Lee, Laura A. Baker, Catherine Tuvblad, Morten Bjerregaard-Andersen, Henning Beck-Nielsen, Morten Sodemann, Kauko Heikkilä, Qihua Tan, Dongfeng Zhang, Gary E. Swan, Ruth Krasnow, Kerry L. Jang, Ariel Knafo-Noam, David Mankuta, Lior Abramson, Paul Lichtenstein, Robert F. Krueger, Matt McGue, Shandell Pahlen, Per Tynelius, Glen E. Duncan, Dedra Buchwald, Robin P. Corley, Brooke M. Huibregtse, Tracy L. Nelson, Keith E. Whitfield, Carol E. Franz, William S. Kremen, Michael J. Lyons, Syuichi Ooki, Ingunn Brandt, Thomas Sevenius Nilsen, Fujio Inui, Mikio Watanabe, Meike Bartels, Toos C. E. M. van Beijsterveldt, Jane Wardle, Clare H. Llewellyn, Abigail Fisher, Esther Rebato, Nicholas G. Martin, Yoshinori Iwatani, Kazuo Hayakawa, Joohon Sung, Jennifer R. Harris, Gonneke Willemsen, Andreas Busjahn, Jack H. Goldberg, Finn Rasmussen, Yoon-Mi Hur, Dorret I. Boomsma, Thorkild I. A. Sørensen, Jaakko Kaprio, Karri Silventoinen
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- Twin Research and Human Genetics / Volume 18 / Issue 5 / October 2015
- Published online by Cambridge University Press:
- 04 September 2015, pp. 557-570
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A trend toward greater body size in dizygotic (DZ) than in monozygotic (MZ) twins has been suggested by some but not all studies, and this difference may also vary by age. We analyzed zygosity differences in mean values and variances of height and body mass index (BMI) among male and female twins from infancy to old age. Data were derived from an international database of 54 twin cohorts participating in the COllaborative project of Development of Anthropometrical measures in Twins (CODATwins), and included 842,951 height and BMI measurements from twins aged 1 to 102 years. The results showed that DZ twins were consistently taller than MZ twins, with differences of up to 2.0 cm in childhood and adolescence and up to 0.9 cm in adulthood. Similarly, a greater mean BMI of up to 0.3 kg/m2 in childhood and adolescence and up to 0.2 kg/m2 in adulthood was observed in DZ twins, although the pattern was less consistent. DZ twins presented up to 1.7% greater height and 1.9% greater BMI than MZ twins; these percentage differences were largest in middle and late childhood and decreased with age in both sexes. The variance of height was similar in MZ and DZ twins at most ages. In contrast, the variance of BMI was significantly higher in DZ than in MZ twins, particularly in childhood. In conclusion, DZ twins were generally taller and had greater BMI than MZ twins, but the differences decreased with age in both sexes.
The CODATwins Project: The Cohort Description of Collaborative Project of Development of Anthropometrical Measures in Twins to Study Macro-Environmental Variation in Genetic and Environmental Effects on Anthropometric Traits
- Karri Silventoinen, Aline Jelenkovic, Reijo Sund, Chika Honda, Sari Aaltonen, Yoshie Yokoyama, Adam D. Tarnoki, David L. Tarnoki, Feng Ning, Fuling Ji, Zengchang Pang, Juan R. Ordoñana, Juan F. Sánchez-Romera, Lucia Colodro-Conde, S. Alexandra Burt, Kelly L. Klump, Sarah E. Medland, Grant W. Montgomery, Christian Kandler, Tom A. McAdams, Thalia C. Eley, Alice M. Gregory, Kimberly J. Saudino, Lise Dubois, Michel Boivin, Claire M. A. Haworth, Robert Plomin, Sevgi Y. Öncel, Fazil Aliev, Maria A. Stazi, Corrado Fagnani, Cristina D’Ippolito, Jeffrey M. Craig, Richard Saffery, Sisira H. Siribaddana, Matthew Hotopf, Athula Sumathipala, Timothy Spector, Massimo Mangino, Genevieve Lachance, Margaret Gatz, David A. Butler, Gombojav Bayasgalan, Danshiitsoodol Narandalai, Duarte L. Freitas, José Antonio Maia, K. Paige Harden, Elliot M. Tucker-Drob, Kaare Christensen, Axel Skytthe, Kirsten O. Kyvik, Changhee Hong, Youngsook Chong, Catherine A. Derom, Robert F. Vlietinck, Ruth J. F. Loos, Wendy Cozen, Amie E. Hwang, Thomas M. Mack, Mingguang He, Xiaohu Ding, Billy Chang, Judy L. Silberg, Lindon J. Eaves, Hermine H. Maes, Tessa L. Cutler, John L. Hopper, Kelly Aujard, Patrik K. E. Magnusson, Nancy L. Pedersen, Anna K. Dahl Aslan, Yun-Mi Song, Sarah Yang, Kayoung Lee, Laura A. Baker, Catherine Tuvblad, Morten Bjerregaard-Andersen, Henning Beck-Nielsen, Morten Sodemann, Kauko Heikkilä, Qihua Tan, Dongfeng Zhang, Gary E. Swan, Ruth Krasnow, Kerry L. Jang, Ariel Knafo-Noam, David Mankuta, Lior Abramson, Paul Lichtenstein, Robert F. Krueger, Matt McGue, Shandell Pahlen, Per Tynelius, Glen E. Duncan, Dedra Buchwald, Robin P. Corley, Brooke M. Huibregtse, Tracy L. Nelson, Keith E. Whitfield, Carol E. Franz, William S. Kremen, Michael J. Lyons, Syuichi Ooki, Ingunn Brandt, Thomas Sevenius Nilsen, Fujio Inui, Mikio Watanabe, Meike Bartels, Toos C. E. M. van Beijsterveldt, Jane Wardle, Clare H. Llewellyn, Abigail Fisher, Esther Rebato, Nicholas G. Martin, Yoshinori Iwatani, Kazuo Hayakawa, Finn Rasmussen, Joohon Sung, Jennifer R. Harris, Gonneke Willemsen, Andreas Busjahn, Jack H. Goldberg, Dorret I. Boomsma, Yoon-Mi Hur, Thorkild I. A. Sørensen, Jaakko Kaprio
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- Twin Research and Human Genetics / Volume 18 / Issue 4 / August 2015
- Published online by Cambridge University Press:
- 27 May 2015, pp. 348-360
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For over 100 years, the genetics of human anthropometric traits has attracted scientific interest. In particular, height and body mass index (BMI, calculated as kg/m2) have been under intensive genetic research. However, it is still largely unknown whether and how heritability estimates vary between human populations. Opportunities to address this question have increased recently because of the establishment of many new twin cohorts and the increasing accumulation of data in established twin cohorts. We started a new research project to analyze systematically (1) the variation of heritability estimates of height, BMI and their trajectories over the life course between birth cohorts, ethnicities and countries, and (2) to study the effects of birth-related factors, education and smoking on these anthropometric traits and whether these effects vary between twin cohorts. We identified 67 twin projects, including both monozygotic (MZ) and dizygotic (DZ) twins, using various sources. We asked for individual level data on height and weight including repeated measurements, birth related traits, background variables, education and smoking. By the end of 2014, 48 projects participated. Together, we have 893,458 height and weight measures (52% females) from 434,723 twin individuals, including 201,192 complete twin pairs (40% monozygotic, 40% same-sex dizygotic and 20% opposite-sex dizygotic) representing 22 countries. This project demonstrates that large-scale international twin studies are feasible and can promote the use of existing data for novel research purposes.
Stability in symptoms of anxiety and depression as a function of genotype and environment: a longitudinal twin study from ages 3 to 63 years
- M. G. Nivard, C. V. Dolan, K. S. Kendler, K.-J. Kan, G. Willemsen, C. E. M. van Beijsterveldt, R. J. L. Lindauer, J. H. D. A. van Beek, L. M. Geels, M. Bartels, C. M. Middeldorp, D. I. Boomsma
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- Psychological Medicine / Volume 45 / Issue 5 / April 2015
- Published online by Cambridge University Press:
- 04 September 2014, pp. 1039-1049
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Background.
The influence of genetic factors on major depressive disorder is lower than on other psychiatric disorders. Heritability estimates mainly derive from cross-sectional studies, and knowledge on the longitudinal aetiology of symptoms of anxiety and depression (SxAnxDep) across the lifespan is limited. We aimed to assess phenotypic, genetic and environmental stability in SxAnxDep between ages 3 and 63 years.
Method.We used a cohort-sequential design combining data from 49 524 twins followed from birth to age ⩾20 years, and from adolescence into adulthood. SxAnxDep were assessed repeatedly with a maximum of eight assessments over a 25-year period. Data were ordered in 30 age groups and analysed with longitudinal genetic models.
Results.Over age, there was a significant increase during adolescence in mean scores with sex differences (women>men) emerging. Heritability was high in childhood and decreased to 30–40% during adulthood. This decrease in heritability was due to an increase in environmental variance. Phenotypic stability was moderate in children (correlations across ages ~0.5) and high in adolescents (r = 0.6), young adults (r = 0.7), and adults (r = 0.8). Longitudinal stability was mostly attributable to genetic factors. During childhood and adolescence there was also significant genetic innovation, which was absent in adults. Environmental effects contributed to short-term stability.
Conclusions.The substantial stability in SxAnxDep is mainly due to genetic effects. The importance of environmental effects increases with age and explains the relatively low heritability of depression in adults. The environmental effects are transient, but the contribution to stability increases with age.
Twins, Tissue, and Time: An Assessment of SNPs and CNVs
- Paul Scheet, Erik A. Ehli, Xiangjun Xiao, Catharina E. M. van Beijsterveldt, Abdel Abdellaoui, Robert R. Althoff, Jouke Jan Hottenga, Gonneke Willemsen, Kelly A. Nelson, Patricia E. Huizenga, Yueshan Hu, Christopher I. Amos, Meike Bartels, Maria M Groen-Blokhuis, Eco JC de Geus, James J. Hudziak, Gareth E. Davies, Dorret I. Boomsma
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- Twin Research and Human Genetics / Volume 15 / Issue 6 / December 2012
- Published online by Cambridge University Press:
- 28 September 2012, pp. 737-745
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With the desire to assess genetic variation across the lifespan in large-scale collaborative projects, one question is whether inference of copy number (CN) is sensitive to the source of material for deoxyribonucleic acid (DNA) analysis (e.g., blood and buccal) and another question is whether CN is stable as individuals age. Here, we address these questions by applying Affymetrix 6.0 single nucleotide polymorphism (SNP) micro-arrays to 1,472 DNA samples from 710 individuals from the Netherlands Twin Register, including twin and non-twin individuals (372 with buccal and blood derived DNA and 388 with longitudinal data). Similar concordance for CN and genotype inference between samples from the same individual [or from the monozygotic (MZ) co-twins] was found for blood and buccal tissues. There was a small but statistically significant decrease in across-tissue concordance compared with concordance of samples from the same tissue type. No temporal effect was seen on CN variation from the 388 individuals sampled at two time points ranging from 1 to 12 years apart. The majority of our individuals were sampled at age younger than 20 years. Genotype concordance was very high (R2 > 99%) between co-twins from 43 MZ pairs. For 75 dizygotic (DZ) pairs, R2 was ≈65%. CN estimates were highly consistent between co-twins from MZ pairs for both deletions (R2 ≈ 90%) and duplications (R2 ≈ 86%). For DZ, these were similar for within-individual comparisons, but naturally lower between co-twins (R2 ≈ 50–60%). These results suggest that DNA from buccal samples perform as well as DNA from blood samples on the current generation of micro-array technologies.
Variation in BMPR1B, TGFRB1 and BMPR2 and Control of Dizygotic Twinning
- Hien T. T. Luong, Justin Chaplin, Allan F. McRae, Sarah E. Medland, Gonneke Willemsen, Dale R. Nyholt, Anjali K. Henders, Chantal Hoekstra, David L. Duffy, Nicholas G. Martin, Dorret I. Boomsma, Grant W. Montgomery, Jodie N. Painter
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- Twin Research and Human Genetics / Volume 14 / Issue 5 / 01 October 2011
- Published online by Cambridge University Press:
- 21 February 2012, pp. 408-416
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Genes in the TGF9 signaling pathway play important roles in the regulation of ovarian follicle growth and ovulation rate. Mutations in three genes in this pathway, growth differentiation factor 9 (GDF9), bone morphogenetic protein 15 (BMP15) and the bone morphogenetic protein receptor B 1 (BMPRB1), influence dizygotic (DZ) twinning rates in sheep. To date, only variants in GDF9 and BMP15, but not their receptors transforming growth factor ß receptor 1 (TGFBR1), bone morphogenetic protein receptor 2 (BMPR2) and BMPR1B, have been investigated with respect to their roles in human DZ twinning. We screened for rare and novel variants in TGFBR1, BMPR2 and BMPR1B in mothers of dizygotic twins (MODZT) from twin-dense families, and assessed association between genotyped and imputed variants and DZ twinning in another large sample of MODZT. Three novel variants were found: a deep intronic variant in BMPR2, and one intronic and one non-synonymous exonic variant in BMPRB1 which would result in the replacement of glutamine by glutamic acid at amino acid position 294 (p.Gln294Glu). None of these variants were predicted to have major impacts on gene function. However, the p.Gln294Glu variant changes the same amino acid as a sheep BMPR1B functional variant and may have functional consequences. Six BMPR1B variants were marginally associated with DZ twinning in the larger case-control sample, but these were no longer significant once multiple testing was taken into account. Our results suggest that variation in the TGF9 signaling pathway type II receptors has limited effects on DZ twinning rates in humans.
Highly Resistant Gram-Negative Microorganisms Incidence Density and Occurrence of Nosocomial Transmission (TRIANGLe Study)
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- I. Willemsen, S. Elberts, C. Verhulst, M. Rijnsburger, M. Filius, P. Savelkoul, J. Kluytmans, TRIANGLe Study Group, E. Lommerse, L. Spanjaard, B. Vlaminckx, A. Vos, M. Wulf, M. Vos, R. Wintermans, G. Andriesse, J. van Zeijl, E. van der Vorm, A. Buiting, P. Sturm, H. Blok, A. Troelstra, A. Kaiser, C. Vandenbroucke-Grauls
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- Journal:
- Infection Control & Hospital Epidemiology / Volume 32 / Issue 4 / April 2011
- Published online by Cambridge University Press:
- 02 January 2015, pp. 333-341
- Print publication:
- April 2011
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Objectives.
The objectives of this study were to determine the incidence density and the occurrence of horizontal spread of highly resistant gram-negative rods (HR-GNRs) in Dutch hospitals. The factors that influence these outcome measures were also investigated.
Methods.All patients with HR-GNRs, as determined by sample testing, who were hospitalized in 1 of 18 hospitals during a 6-month period (April through October 2007) were included in this study. For all available isolates, the species was identified, susceptibility was determined (including the presence of extended-spectrum β-lactamases [ESBLs]), and molecular typing was performed. On the basis of a combination of species identification, molecular typing, and epidemiological data, the occurrence of nosocomial transmission was determined.
Results.The mean incidence density of patients with HR-GNRs was 55 per 100,000 patient-days (cumulative incidence, 39 per 10,000 patients admitted). A facility being a university hospital was a statistically significant (P = .03) independent determinant of a higher incidence of patients with HR-GNRs. The majority of HR-GNR isolates were ESBL producers. The adjusted transmission index—the ratio between secondary and primary cases—in the participating hospitals ranged from 0.0 to 0.2. The overall adjusted transmission index of HR-GNRs was 0.07. No determinants for a higher transmission index were identified.
Discussion.The nosocomial transmission rate of HR-GNRs was relatively low in all hospitals where well-established transmission-based precautions were used. The incidence density of patients with HR-GNRs was higher in university hospitals, probably due to the patient population and the complexity of the care provided.
Variation in adult survival rate of the tortoise Testudo hermanni in Greece: implications for evolution of body size
- R. E. Willemsen, A. Hailey
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- Journal:
- Journal of Zoology / Volume 255 / Issue 1 / September 2001
- Published online by Cambridge University Press:
- 29 August 2001, pp. 43-53
- Print publication:
- September 2001
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Adult annual survival rates estimated by mark–recapture for eight Greek populations of the tortoise Testudo hermanni were in the range 0.80–1.0 (mean 0.886). Estimates from growth rings for the same populations were in a similar range (0.84–0.95, mean 0.899). The average survival rate from the two methods was significantly positively related to mean adult body size (r=0.815) and negatively related to effective temperature (r=−0.880). A life table model was used to investigate the consequences of adult survival rate for optimum age at maturity and mean adult size of females. The basis of the model was the trade-off between increased reproduction from large adult size, and decreased survival to maturity from delayed age at maturity. The model showed that the observed variation in adult survival rates was more than sufficient to account for the variation of adult size among populations. The model thus predicted an even greater range of mean adult size than that observed. A negative correlation between growth rate and adult survival rate or age at maturity, as observed, was needed to fit the size data. The model supports the hypothesis that variation in adult size of T. hermanni in Greece is adaptive (rather than a non-adaptive environmental or phylogenetic effect) and due to variation in adult survival rates (rather than other factors such as juvenile survival).
Population density and adult sex ratio of the tortoise Testudo hermanni in Greece: evidence for intrinsic population regulation
- A. Hailey, R. E. Willemsen
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- Journal:
- Journal of Zoology / Volume 251 / Issue 3 / July 2000
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- 01 July 2000, pp. 325-338
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- July 2000
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The idea that the size of animal populations may be regulated by factors intrinsic to them, such as behaviour, has a long history in ecology. Although this idea is now rejected as a general mechanism, it may apply in some species where females are damaged during courtship attempts, such as the Mediterranean tortoise Testudo hermanni. The sex ratios (adult males : adult females) of most dense Greek populations were more extreme (over 1.5:1) than could be accounted for by the earlier age at maturity of males, and some ranged to over 6:1. The sex ratio was correlated with the population density of adult males and the frequency of courtship attempts on females, and negatively correlated with the longevity of females. A high population density of males limits the density of adult females. This intrinsic regulation of population size is a consequence, rather than a goal, of a particular type of courtship behaviour (persistent thrusts by the male using a tail with a sharp terminal spur) in T. hermanni. Existing population densities at many Greek sites are probably unnaturally high, owing to the reduction of natural predators.
Variation of adult body size of the tortoise Testudo hermanni in Greece: proximate and ultimate causes
- R. E. Willemsen, A. Hailey
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- Journal:
- Journal of Zoology / Volume 248 / Issue 3 / July 1999
- Published online by Cambridge University Press:
- 01 July 1999, pp. 379-396
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- July 1999
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Seventeen populations of T. hermanni in Greece differed substantially in mean adult body size, over a range of about one and a half times in length and three times in mass. Females were the larger sex in all populations; the degree of sexual size dimorphism did not vary with mean body size. The proximate cause of the variation of body size among populations was differences in the duration of growth, rather than egg or hatchling size or the growth rates of juveniles. The age at maturity (α) increased with body size in the 17 populations, while the Bertalanffy growth constant (k) decreased with body size. The quantities αM and M/k (where M is the instantaneous mortality rate) were invariant with body size, suggesting that differences between populations were adaptive rather than the result of short-term disturbance. Body size was greater in cooler areas, and increased with both latitude and altitude. This pattern is opposite to that found in most ectotherms (the reverse Bergmann's rule), and to that which occurs between tortoise species. Several hypotheses about the possible ultimate causes of variation of body size were rejected, including adaptation to long-term habitat disturbance (land use), character displacement, social factors, energetics, thermoregulation, r-K selection, the length of the season available for incubation, or differences in juvenile mortality. The most likely ultimate cause of size variation between sites is differences in adult mortality, the correlation with environmental temperature being through the frequency of fires.