Akademik Veri Yönetim Sistemi
Epigenetics: Beyond the Genetics and Medicine, Durna Daştan Sevgi,Yurtçu Nazan, Editör, NOVA Science Publishers Inc. , New York, ss.41-52, 2022
Genetics cannot solely explain genetic variations in humans and disease developments. We
see varying differences in phenotypes and disease susceptibility in organisms that have the
same genetic make-up, e.g., monozygotic twins and cloned animals. The information
carried by the genomic sequence is the blueprint, but the final product requires
environmental determinants. Here comes the concept of epigenetics, as it is the framework
where biochemical interactions between the genome and the environment blend. We can
describe epigenetics as mechanisms that are beyond genetics, as such mechanisms alter the
result of the genomic blueprint without altering the information itself, i.e., the sequence.
Both epigenetics and epigenomics are trending research fields to better evaluate the
genotype and the phenotype. The methylation of genetic material is a well-studied and
well-known epigenetic marker. The epigenome, as a term, describes the inheritable
changes in both the DNA and histone molecular structures, where the methylation and
acetylation mechanisms are studied extensively. As the building blocks of the chromatin
structure, nucleosomes depend on epigenetic changes, which lead to becoming either tight
or loose, based on the particular mechanisms. Chromatin structure changes directly affect
the gene expression, e.g., particular gene expression becomes silenced if the gene position
has DNA hypermethylation and histone hypoacetylation that leads to the condensed form
of the chromatin. Inversely, if the said changes were removed, genes in that position would
express themselves again. Therefore, epigenetics provides a vigorous and remarkably
malleable means for gene expression regulations. Epigenomics includes both the
epigenetic mechanisms on the DNA and histones and complicated interactions between the
genotype and the phenotype. There are well-known epigenomic changes in DNA, RNA,
and protein levels. DNA base changes in somatic cells and chromosome positioning are
among the aspects determining the epigenomic scene. Alternative splicing mechanism,
RNA processing (editing, capping, Poly-A tailing, etc.), RNA methylation, and regulations
conferred by the non-coding RNAs (ncRNAs) are RNA level epigenomic changes.
Epigenomic changes at the protein level include various mechanisms of the post-
translational modification. Epigenomics research includes total hypomethylation profile of
the genome, identification of hypermethylated genes, microRNA-driven gene silencing with DNA methylation, epigenome projects, and DNA-based clinical therapies for
different biomedical conditions. This chapter will detail fundamental concepts and basic
approaches to both epigenomics and epigenomes.