Back mutation refers to the reversal of a previously mutated gene to its original state. This process is also known as reversion mutation, reverse mutation, or up mutation. In genetic terms, back mutation occurs when a nucleotide is substituted back to its original form, thereby reversing the effects of the initial mutation. This translates to a restoration of a lost genetic trait or function. Other common synonyms for back mutation include reverse genetics, loss-of-function, and wild type. Understanding back mutation is essential in gene therapy research as it highlights the possibility of recovering lost genetic traits by reversing undesirable mutations.