Twins, Monozygotic

Publication Title: 
Scandinavian Journal of Public Health

INTRODUCTION: The Danish Twin Registry (DTR) has for more than 50 years been based on surveys and clinical investigations and over the two last decades also on register linkage. Currently these two approaches are merged within Statistics Denmark. RESEARCH TOPICS: Here we report on three major groups of register-based research in the DTR that used the uniqueness of twinning.

Christensen, Kaare
Kyvik, Kirsten Ohm
Holm, Niels V.
Skytthe, Axel
Publication Title: 
PLoS genetics

Age-related changes in DNA methylation have been implicated in cellular senescence and longevity, yet the causes and functional consequences of these variants remain unclear. To elucidate the role of age-related epigenetic changes in healthy ageing and potential longevity, we tested for association between whole-blood DNA methylation patterns in 172 female twins aged 32 to 80 with age and age-related phenotypes.

Bell, Jordana T.
Tsai, Pei-Chien
Yang, Tsun-Po
Pidsley, Ruth
Nisbet, James
Glass, Daniel
Mangino, Massimo
Zhai, Guangju
Zhang, Feng
Valdes, Ana
Shin, So-Youn
Dempster, Emma L.
Murray, Robin M.
Grundberg, Elin
Hedman, Asa K.
Nica, Alexandra
Small, Kerrin S.
MuTHER Consortium
Dermitzakis, Emmanouil T.
McCarthy, Mark I.
Mill, Jonathan
Spector, Tim D.
Deloukas, Panos
Publication Title: 
Experimental Gerontology

Cellular senescence is a biological process associated with aging and longevity. Successful aging is believed to be related to the ability to cope with different environmental stresses. The objective of this study was to investigate if cellular senescence is associated with platelet membrane modifications on subjects of different age, in particular on monozygotic twins and if these changes might be affected by both genetic components and environmental factors. The work was performed on 81 monozygotic twin pairs of different age.

Nanetti, Laura
Laura, Nanetti
Moroni, Cinzia
Cinzia, Moroni
Vignini, Arianna
Arianna, Vignini
Vannini, Patrizia
Patrizia, Vannini
Franceschi, Claudio
Claudio, Franceschi
Mazzanti, Laura
Laura, Mazzanti
Publication Title: 
Psychiatry Research

Fluctuating asymmetry of bilateral morphological traits is the result of prenatal developmental instability and has been shown to be greater in organisms having more homozygous genotypes (aabb vs. AaBb, for example). This expected increase in fluctuating asymmetry has been found among individuals having a high degree of liability for schizophrenia, as this disorder appears to have a polygenic basis.

Markow, T. A.
Gottesman, I. I.
Publication Title: 
Twin Research: The Official Journal of the International Society for Twin Studies

Non-linear epigenetic processes are a potential underlying source of phenotypic differences in development. Simulation studies of twin pairs using simple non-linear development models characterised by chaotic or near-chaotic behavior are presented. The effect of chaotic processes on correlations is to lower them from their initial values, but high initial correlations are affected much less by chaotic and near-chaotic processes than intermediate correlations.

Eaves, L. J.
Kirk, K. M.
Martin, N. G.
Russell, R. J.
Publication Title: 
Journal of Child Psychology and Psychiatry, and Allied Disciplines

BACKGROUND: Genotype x environment interaction (G x E) arises when genes influence sensitivity to the environment. G x E is easily recognized in experimental organisms that permit randomization of genotypes over fixed environmental treatments. Genotype-environment correlation (rGE) arises when genetic effects create or evoke exposure to environmental differences.

Eaves, Lindon
Silberg, Judy
Erkanli, Alaattin
Publication Title: 
Human Molecular Genetics

Human monozygotic twins and other genetically identical organisms are almost always strikingly similar in appearance, yet they are often discordant for important phenotypes including complex diseases. Such variation among organisms with virtually identical chromosomal DNA sequences has largely been attributed to the effects of environment.

Wong, Albert H. C.
Gottesman, Irving I.
Petronis, Arturas
Publication Title: 
Molecular Psychiatry

Classical twin research focused on differentiating genetic factors from environmental factors by comparing the concordance rate between monozygotic (MZ) and dizygotic twins. On the other hand, recent twin research tries to identify genetic or epigenetic differences between MZ twins discordant for mental disorders. There are a number of reports of MZ twins discordant for genetic disorders caused by genetic or epigenetic differences of known pathogenic genes.

Kato, T.
Iwamoto, K.
Kakiuchi, C.
Kuratomi, G.
Okazaki, Y.
Publication Title: 
American Journal of Medical Genetics. Part B, Neuropsychiatric Genetics: The Official Publication of the International Society of Psychiatric Genetics

Monozygotic (MZ) twin concordance for a range of psychiatric conditions is rarely 100%. It has been suggested that epigenetic factors, such as DNA methylation, may account for a proportion of the variation in behavioral traits observed between these genetically identical individuals. In this study we have quantitatively assessed the methylation status of two CpG sites in the promoter region of the COMT gene in 12 MZ twins-pairs discordant for birth weight, but otherwise clinically unaffected. DNA was obtained at age 5-years using buccal swabs, and modified using sodium-bisulfite treatment.

Mill, Jonathan
Dempster, Emma
Caspi, Avshalom
Williams, Benjamin
Moffitt, Terrie
Craig, Ian
Publication Title: 
American Journal of Medical Genetics. Part B, Neuropsychiatric Genetics: The Official Publication of the International Society of Psychiatric Genetics

Monozygotic (MZ) twins may be subject to epigenetic modifications that could result in different patterns of gene expression. Several lines of evidence suggest that epigenetic factors may underlie mental disorders such as bipolar disorder (BD) and schizophrenia (SZ). One important epigenetic modification, of relevance to female MZ twins, is X-chromosome inactivation. Some MZ female twin pairs are discordant for monogenic X linked disorders because of differential X inactivation.

Rosa, Araceli
Picchioni, Marco M.
Kalidindi, Sridevi
Loat, Caroline S.
Knight, Joanne
Toulopoulou, Timothea
Vonk, Ronald
van der Schot, Astrid C.
Nolen, Willem
Kahn, RenÈ S.
McGuffin, Peter
Murray, Robin M.
Craig, Ian W.


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