You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information.
What is Genes in CpP island is inactivated by: and explain in detail?
Ans: a. Methylation[Ref Lippincott 6th/709; Harrison 19th/101e-4, 18th/668, 679; Robbins 9th/893; Satyanarayan 3rd/359, 572; Lippincott 4th/460-62; Chatterjea Shinde 7th/346, 426; en. wikipedia. org/wiki/DNA_methylationjCpG islands: Methylation of cytosine by a methyltransferase is associated with silencing of the activities of ceain gene"-Lippincott 6th/709Cytosine in the sequence CG of DNA gets methylated to form 5'-methylcytosine. A major poion of CG (about 20%) in human DNA exists in methylated form. In general, methylation leads to loss of transcriptional activity & thus inactivation of genes.The role of epigenetic control mechanisms in the development of human cancer is unclear. However, a general decrease in the level of DNA methylation has been noted as a common change in cancer. In addition, numerous genes, including some tumor-suppressor genes, appear to become hypermethylated and silenced during tumorigenesis.