The field of epigenetics is an emerging area. It aims to strengthen …

• Abstract
• Introduction
• Epigenesis was unknown during the time of Gregor Mendel
• Epigenesis
• DNA Methylation and Histone Deacetylation
• Epigenetic Regulation of Development and Tissue Specificity
• Methylation of CpG Islands
• Epigenetic Regulation of Imprinted Genes
• Variable expressivity of genes
• Epigenetics and Clinical Applications
• Human Epigenome Project
• Acknowledgements
• References
• Table 1
• Table 2
• Table 3
• Figures

Geneticists have been fascinated by mammalian alleles that are variably expressed, even in the absence of gene sequence variability (Table 2).  Rakyan Vardhman et al (11) have noticed the expression of two epialleles viz., murine A^vy (Agouti variable yellow) and axin fused (Axin ^Fu) alleles.  Variable expressivity (variegation) of these two epialleles was attributed to their epigenetic state.  Ex, Isogenic mice that carry A^vy allele display a range of cot colours from completely yellow to wild type agouti.  A yellow coat correlates with a hypomethylated state and therefore an active epiallele.  In a similar vein, Auxin fused gene in mouse exhibits phenotypic classification as follows: normal tail non kinky, slightly kinky, kinky and very kinky. Such variations could be explained through epigenetic phenomenon.