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Monozygotic (MZ) twins and higher-order multiples arise when a zygote splits during pre-implantation stages of development. The mechanisms underpinning this event have remained a mystery. Because MZ twinning rarely runs in families, the leading hypothesis is that it occurs at random. Here, we show that MZ twinning is strongly associated with a stable DNA methylation signature in adult somatic tissues. This signature spans regions near telomeres and centromeres, Polycomb-repressed regions and heterochromatin, genes involved in cell-adhesion, WNT signaling, cell fate, and putative human metastable epialleles. Our study also demonstrates a never-anticipated corollary: because identical twins keep a lifelong molecular signature, we can retrospectively diagnose if a person was conceived as monozygotic twin.
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http://dx.doi.org/10.1038/s41467-021-25583-7 | DOI Listing |
Sci Justice
September 2025
Departamento de Medicina Legal, Bioética, Medicina do Trabalho e Medicina Física e Reabilitação, Faculdade de Medicina FMUSP, Universidade de São Paulo, São Paulo, SP, Brazil. Electronic address:
Short Tandem Repeats (STRs) are the standard technique used in forensic genetics for individual identification due to their high polymorphism and robustness. Although Capillary Electrophoresis (CE) enables the analysis of many STRs, Next-Generation Sequencing (NGS) offers enhanced resolution and the ability to detect STRs' isoalleles and their flanking regions, enhancing the discrimination power of this analysis. Despite the fact that STR kits for NGS are well standardized for evaluating forensic samples, there is no data on their effectiveness in differentiating monozygotic (MZ) twins, which are indistinguishable by CE.
View Article and Find Full Text PDFDiabetes Obes Metab
September 2025
Turku PET Centre, University of Turku, Turku, Finland.
Aims: Obesity is associated with increased insulin-stimulated brain glucose uptake (BGU) which is opposite to decreased GU observed in peripheral tissues. Increased BGU was shown to be reversed by weight loss and exercise training, but the mechanisms remain unknown. We investigated whether neuroinflammation (TSPO availability) and brain activity drive the obesity-associated increase in BGU and whether this increase is reversed by exercise training.
View Article and Find Full Text PDFImmun Ageing
September 2025
Department of Biomedical Data Sciences, Molecular Epidemiology, LUMC, Leiden, The Netherlands.
The MetaboHealth score is an indicator of physiological frailty in middle aged and older individuals. The aim of the current study was to explore which molecular pathways co-vary with the MetaboHealth score. Using a Luminex cytokine assay and liquid chromatography-mass spectrometry-based proteomics we explored the plasma proteins associating with the difference in 100 extreme scoring individuals selected from two large population cohorts, the Leiden Longevity Study (LLS) and the Rotterdam Study (RS), and discordant monozygotic twin pairs from the Netherlands Twin Register (NTR).
View Article and Find Full Text PDFNat Commun
September 2025
Shimoda Marine Research Center, University of Tsukuba, Shizuoka, Japan.
Since Hans Driesch's pioneering work in 1891, it has been known that animal embryos can develop into complete individuals even when divided. However, the developmental processes and molecular mechanisms enabling this self-organization remain poorly understood. In this study, we revisit Driesch's experiments by examining the development of isolated 2-cell stage blastomeres in the sea urchin, Hemicentrotus pulcherrimus.
View Article and Find Full Text PDFDeath Stud
September 2025
School of Social Work, Ariel University, Ariel, Israel.
Despite well-documented intimacy within twin relationships, meaning-making processes following twin loss remain underexplored. Using Interpretative Phenomenological Analysis (IPA), this study investigated how individuals reconstruct meaning after losing a twin. Semi-structured interviews with eleven adult twins who lost a twin identified two primary themes: (a) physical amputation and (b) alone in a world meant for two.
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