Mishra, SwetaWhetstine, Johnathan2016-05-022016Mishra, Sweta, and Johnathan R. Whetstine. 2016. “Different Facets of Copy Number Changes: Permanent, Transient, and Adaptive.” Molecular and Cellular Biology 36 (7): 1050-1063. doi:10.1128/MCB.00652-15. http://dx.doi.org/10.1128/MCB.00652-15.0270-7306http://nrs.harvard.edu/urn-3:HUL.InstRepos:26860099Chromosomal copy number changes are frequently associated with harmful consequences and are thought of as an underlying mechanism for the development of diseases. However, changes in copy number are observed during development and occur during normal biological processes. In this review, we highlight the causes and consequences of copy number changes in normal physiologic processes as well as cover their associations with cancer and acquired drug resistance. We discuss the permanent and transient nature of copy number gains and relate these observations to a new mechanism driving transient site-specific copy gains (TSSGs). Finally, we discuss implications of TSSGs in generating intratumoral heterogeneity and tumor evolution and how TSSGs can influence the therapeutic response in cancer.en-USJournal Article2016-05-0210.1128/MCB.00652-15