discovered that the deletion of genes that will eventually allow for the production of histone methyltransferase allows this organism to live as its lysine residues are not methylated. In recent years it has come to the attention of researchers that many types of cancer are caused largely due to epigenetic factors. Cancer can be caused in a variety of ways due to differential methylation of histones. Since the discovery of oncogenes as well as tumor suppressor genes it has been known that a large factor of causing and repressing cancer is within our own genome. If areas around oncogenes become unmethylated these cancer-causing genes have the potential to be transcribed at an alarming rate. Opposite of this is the methylation of tumor suppressor genes. In cases where the areas around these genes were highly methylated, the tumor suppressor gene was not active and therefore cancer was more likely to occur. These changes in methylation pattern are often due to mutations in methyltransferase and demethyltransferase. Other types of mutations in proteins such as isocitrate dehydrogenase 1 (IDH1) and isocitrate dehydrogenase 2 (IDH2) can cause the inactivation of histone demethyltransferase which in turn can lead to a variety of cancers, gliomas and leukemias, depending on in which cells the mutation occurs. One-carbon metabolism modifies histone methylation In one-carbon metabolism, the amino acids glycine and serine are converted via the folate and methionine cycles to nucleotide precursors and SAM. Multiple nutrients fuel one-carbon metabolism, including glucose, serine, glycine, and threonine. High levels of the methyl donor SAM influence histone methylation, which may explain how high SAM levels prevent malignant transformation. See also Histone code Histone acetylation and deacetylation Histone methyltransferase Methylation Methyllysine Genetic Imprinting References Further reading Orouji, Elias & Utikal, Jochen. (2018). Tackling malignant melanoma epigenetically: histone lysine methylation. Clinical Epigenetics 2018 10:145 https://clinicalepigeneticsjournal.biomedcentral.com/articles/10.1186/s13148-018-0583-z Gozani, O., & Shi, Y. (2014). Histone Methylation in Chromatin Signaling. In: Fundamentals of Chromatin (pp. 213–256). Springer New York. Molecular genetics Cellular processes Epigenetics Post-translational modification