Many lines of evidence, including epidemiologic data and extensive clinical and experimental studies, indicate that early life events play a powerful role in influencing later susceptibility to certain chronic diseases. This review synthesizes evidence from several disciplines to support the contention that environmental factors acting during development should be accorded greater weight in models of disease causation.

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Effect of In Utero and Early-Life Conditions on Adult Health and Disease

Gene transcription can be activated or inhibited by a reversible modification of the gene; this modification is termed an epigenetic change. This account of epigenetics in cancer reviews the mechan...

/pdf/epigenetics-in-cancer-4240m6az4l.pdf

Epigenetics in Cancer

The genomes of many animals, plants and fungi are tagged by methylation of DNA cytosine. To understand the biological significance of this epigenetic mark it is essential to know where in the genome it is located. New techniques are making it easier to map DNA methylation patterns on a large scale and the results have already provided surprises. In particular, the conventional view that DNA methylation functions predominantly to irreversibly silence transcription is being challenged. Not only is promoter methylation often highly dynamic during development, but many organisms also seem to target DNA methylation specifically to the bodies of active genes.

https://birdlab.bio.ed.ac.uk/bird/sites/sbsweb2.bio.ed.ac.uk.bird/files/20.pdf

DNA methylation landscapes: provocative insights from epigenomics

Geneticists study the gene; however, for epigeneticists, there is no obvious 'epigene'. Nevertheless, during the past year, more than 2,500 articles, numerous scientific meetings and a new journal were devoted to the subject of epigenetics. It encompasses some of the most exciting contemporary biology and is portrayed by the popular press as a revolutionary new science--an antidote to the idea that we are hard-wired by our genes. So what is epigenetics?

/pdf/perceptions-of-epigenetics-5bhbda5lid.pdf

Perceptions of epigenetics

Epigenetics is one of the most rapidly expanding fields in biology. The recent characterization of a human DNA methylome at single nucleotide resolution, the discovery of the CpG island shores, the finding of new histone variants and modifications, and the unveiling of genome-wide nucleosome positioning maps highlight the accelerating speed of discovery over the past two years. Increasing interest in epigenetics has been accompanied by technological breakthroughs that now make it possible to undertake large-scale epigenomic studies. These allow the mapping of epigenetic marks, such as DNA methylation, histone modifications and nucleosome positioning, which are critical for regulating gene and noncoding RNA expression. In turn, we are learning how aberrant placement of these epigenetic marks and mutations in the epigenetic machinery is involved in disease. Thus, a comprehensive understanding of epigenetic mechanisms, their interactions and alterations in health and disease, has become a priority in biomedical research.

Epigenetic modifications and human disease

Monozygous twins share a common genotype. However, most monozygotic twin pairs are not identical; several types of phenotypic discordance may be observed, such as differences in susceptibilities to disease and a wide range of anthropomorphic features. There are several possible explanations for these observations, but one is the existence of epigenetic differences. To address this issue, we examined the global and locus-specific differences in DNA methylation and histone acetylation of a large cohort of monozygotic twins. We found that, although twins are epigenetically indistinguishable during the early years of life, older monozygous twins exhibited remarkable differences in their overall content and genomic distribution of 5-methylcytosine DNA and histone acetylation, affecting their gene-expression portrait. These findings indicate how an appreciation of epigenetics is missing from our understanding of how different phenotypes can be originated from the same genotype.

/pdf/epigenetic-differences-arise-during-the-lifetime-of-sg7k6gv36i.pdf

Zarko Stephan

Papers

Epigenetic differences arise during the lifetime of monozygotic twins