Epigenetics involves heritable changes in gene expression that are not caused by changes in the underlying DNA sequence. These changes are caused by mechanisms such as chromatin remodeling and DNA methylation. While genetics is determined by the DNA sequence, epigenetics influences which genes are expressed through modifications to histone proteins and DNA. These epigenetic modifications play important roles in development and can cause diseases if disrupted, such as imprinting disorders. Significant research is being conducted worldwide at top institutions like Johns Hopkins University to better understand epigenetics and its effects.

1. Presented by : SheetalNarkar

2. EpigeneticsHeritable changes in gene expression caused by the mechanisms other than changes in the underlying DNA sequenceEpigenetics However, there is no change in the underlying DNA sequence of the organism; Instead, non-genetic factors cause the organism's genes to behave (or "express themselves") differently.

4. GENETICS VERSUS EPIGENETICSGENETICSEPIGENETICS

5. Molecular Basis of Epigenetics

6. Molecular Basis of EpigeneticsIt involves modificationsand activation of certain genes, but not the basic structure of DNA

7. Additionally, the chromatin proteins associated with DNA may be activated or silenced

8. This accounts for why the differentiated cells in a multi-cellular organism express only the genes that are necessary for their own activityWhat are those Modifications ?1. Chromatin Remodeling :It is the post translational modification of the amino acids that make up histoneproteins

9. As the histones increase the compaction of the DNA , it depresses the genetic activity ; and vice–a-versaWhat are those Modifications ?2. DNA Methylation :It is the addition of methyl groups to the DNA, mostly at CpG sites, to convert cytosine to 5-methylcytosine

10. Some areas of genome are methylated heavier than others and highly methylated areas tend to be transcriptionally less activeEpigenetic Effects in HumansGenomic imprinting and related disorders

11. Cancer and developmental abnormalities

12. Twin studiesEpigenetic Effects in HumansGenomic imprinting and related disorders

13. Most mammalian autosomal genes are expressed from both the maternally inherited and paternally inherited copies of the chromosomes

14. However, some genes are expressed in a parent-of-origin–specific manner. This phenomenon, known as genomic imprintingGenomic imprintingImprinted genes are either expressed only from the allele inherited from the mother (eg. H19 ), or in other instances from the allele inherited from the father (eg. IGF2).

15. Importance of Imprinted GenesPlay a major role in the embryonic growth and development

16. Imprinting defects results in various genetic diseases including:

17. Beckwith-Wiedemann syndrome,

18. Silver-Russell Syndrome,

19. Angelman Syndrome and

20. Prader-Willi SyndromeIGF2Function in embryo growth & developmentIGF2Monoallelic Expression Genomic Imprinting… An Epigenetic Event… The differential expression of a gene or chromosomal region according to parental origin of inheritanceInsulin-like Growth Factor 2 (IGF2)

21. Closer look at IGF2 Locus……Enhancer competition at IGF2-H19 locus

22. Epigenetics Research InstitutesThere are a total of 4,877 institutions engaged in the research on EpigeneticsAmong the top 20, fourteen of the institutions are US-based, four hail from the UK, and one is from Austria

23. Top 10 Research InstitutesJohns Hopkins University tops the list, with 347 papersHarvard University, with 307 papers National Cancer Institute of the US with 284 papersUniversity of Southern California, with 114 papersUniversity of Virginia, with 45 papers

24. Top 10 Research InstitutesUniversity of Cambridge with 155 papers MIT, with 87 papersVienna Biocenter, with 25 papersUniversity of California, San Francisco, with 146 papers UK's Babraham Institute, with 81 papers

25. To date, approximately 50 imprinted genes have been identified in the human genome (Morison IM, Reeve AE 1998; Morison IM, Ramsay JP, Spencer HG 2005; Glaser RL, Ramsay JP, Morison IM 2006)Worldwide Research Going On