WordNet
mutant gene
n. a gene that has changed so that the normal transmission and expression of a trait is affected
Usage examples of "mutant gene".
The trigger can be a virus, or radiation, or a carcinogenic chemical, or a mutant gene that is inherited, or even a failure of the body's autore.
Hence cases have turned up repeatedly of beautiful women fashion models not realizing that they are actually men with a single mutant gene until genetically tested as adults.