Epigenetics: a Historical Overview

In the first half of the twentieth century, developmental biology and genetics were separate disciplines

image of epigenetics
The nature of the continual interactions between proteins and DNA will further advance the field of epigenetics, and illuminate current problems, such as the re-programming of the genome which initiates the normal processes of development.

ABSTRACT

Epigenetics attempts to provide new insights into the mechanisms for unfolding the genetic program for development.

The word epigenetics was coined by Waddington to link developmental biology and genetics. Epigenetics could be broadly defined as the sum of all those mechanisms necessary for the unfolding of the genetic programme for development. Several decades later specific mechanisms were proposed in which information was superimposed on DNA sequences. In particular, it was suggested that 5-methyl cytosine had a role in controlling gene expression, and also that the pattern of methylation was heritable. These predictions are now supported by a large body of evidence which shows that methylation is strongly associated with gene silencing in a variety of biological contexts. There are now also many examples of epigenetic inheritance through the germ line There are several other important epigenetic mechanisms involving chromatin and histone modifications, and also the expanding field of regulatory RNAs. The human epigenome project will unravel the pattern of DNA methylation in different tissues, and will this determine whether the regulation of gene expression is at the level of DNA or chromatin, or both.

Gene activity and function in the human brain: how enhancers are linked to autism

Brain study reveals insights into genetic basis of autism

Color-and-Shapes
This study is the first to investigate how the activity of enhancers and genes are coordinated in the human brain, and the first to show that brain enhancers are linked to autism. Color and Shapes image by Brian Talbot.

2015 Study Abstract

Despite major progress in identifying enhancer regions on a genome-wide scale, the majority of available data are limited to model organisms and human transformed cell lines.

We have identified a robust set of enhancer RNAs (eRNAs) expressed in the human brain and constructed networks assessing eRNA-gene coexpression interactions across human fetal brain and multiple adult brain regions.

Our data identify brain region–specific eRNAs and show that enhancer regions expressing eRNAs are enriched for genetic variants associated with autism spectrum disorders.

Sources and more information
  • Coexpression networks identify brain region–specific enhancer RNAs in the human brain, Nature Neuroscience, doi:10.1038/nn.4063, 13 July 2015.
  • Brain study reveals insights into genetic basis of autism,
    MedicalXpress, July 13, 2015.