Deletion of a base pair(s) is another common mechanism

Alterations in gene expression occur through many mechanisms which basically involves changing of the base sequences in the genetic material. One of the major mechanism through which gene expression is altered is addition where a base pair is added to the normal sequence hence changing the specificity of the protein that the code specifies. Addition results to production of a nonsense sequence which does not specify any of the proteins.

Deletion of a base pair(s) is another common mechanism where one or more base pairs are deleted from the normal three base sequences. Similar to addition, deletion results to production of nonsense codes (base sequences which do not specify production of any protein). Another mechanism is substitution which involves replacing a specific base pair with a different one. As a result, the sequence specific for a given protein is changed to another code which in rare cases specifies the same protein or specifies the production of a different protein. Another mechanism is inversion where a base pair turns upside down from its normal position.

This may as well lead to formation of a nonsense sequence. Continued accumulation of these genetic alterations which result to altered expression of genes is what causes cancer development. These alterations are known to cause DNA mutations which in turn disrupt the processes that regulate cell proliferation and cell death. The result is uncontrolled division of cells which accumulate and develop into tumors.