EPIGENETICS

• Methylated genes are usually silenced, while unmethylated genes are expressed.
• DNA methylation is an epigenetic modification that involves adding a methyl group (-CH3) to cytosine bases in DNA.
• DNA methylation is an epigenetic modification that involves the addition of a methyl group to cytosine residues within CpG dinucleotides.
• Epigenetics is how gene expression is read and how genotype gives rise to a phenotype
• Epigenetics explains how characteristics are inherited across cell, organism, and generations without changing the DNA sequence itself
• Static DNA code is highly conserved during mitosis and meiosis, relevant to diseases, and identical in all cell types
• Epigenetic code is semi-conserved during mitosis and meiosis, differs between cell types responsive to the environment, and is amenable to pharmacologic intervention
• Epigenetic modifications are signals attached to histones, which maintain the shape of DNA
• Histone modifications involve over 20 different chemical modifications, including the addition of acetyl, methyl, or phosphate groups that can activate or inactivate affected genes
• Chromatin remodeling involves ATP-powered protein complexes that tighten or uncoil chromatin coils or DNA strands
• DNA methylation is a mechanism of controlling DNA replication, with methylation taking place after DNA replication and during cell differentiation
• Methylation involves adding a methyl group to cytosine on the 5-carbon of the cytosine nitrogenous base, leading to gene silencing or inactivation of DNA transcription
• DNA demethylation is the removal of a methyl group from cytosines, and unmethylated DNA can trigger an increase in immune reactivity
• Non-coding RNAs are transcribed from DNA but not translated into proteins, facilitating epigenetic modifications such as adding methyl, acetyl, or phosphate groups
• Two groups of ncRNAs related to epigenetic modification are short ncRNAs (>31 nucleotides) and long ncRNAs (<200 nucleotides)
• Monoallelic gene expression includes parent-of-origin MAE (imprinting) and random monoallelic expression
• Parent-of-origin MAE involves highly methylated DNA in sperm and eggs, with some escaping demethylation and causing mutations like Prader-Willi Syndrome and Angelman Syndrome
• Random MAE of Autosomal genes can lead to different patterns of expression in the same tissue, impacting the phenotype and explaining incomplete penetrance traits in genetic disorders
• Rett syndrome is a rare genetic neurological disorder primarily affecting females, causing a loss of motor skills, language, and other symptoms
• Epigenetic modifications can be used as markers to detect genetic mutations/disorders and offer alternative treatments for various disorders, including psychological and mental illnesses