Gene amplification refers to a number of natural and artificial processes by which the number of copies of a gene is increased "without a proportional increase in other genes".
[1] In research or diagnosis DNA amplification can be conducted through methods such as: DNA replication is a natural form of copying DNA with the amount of genes remaining constant.
However, the amount of DNA or the number of genes can also increase within an organism through gene duplication, a major mechanism through which new genetic material is generated during molecular evolution.
Common sources of gene duplications include ectopic recombination, retrotransposition event, aneuploidy, polyploidy, and replication slippage.
[4] A piece of DNA or RNA that is the source and/or product of either natural or artificial amplification or replication events is called an amplicon.