If the gene in question is the wildtype a superscript + sign is used:
*leuA
If a gene is mutant, it is signified by a superscript -:
*leuA
By convention, if neither is used, it is considered to be mutant.
There are additional superscripts and subscripts which provide more information about the mutation:
* = temperature sensitive (leuA)
* = cold sensitive (leuA)
* = amber mutation (leuA)
* = umber (opal) mutation (leuA)
* = ochre mutation (leuA)
* = resistant (Rif)
Other modifiers:
*Δ = deletion (ΔleuA)
*- = fusion (leuA-lacZ)
* = fusion (leuA:lacZ)
* = insertion (leuA::Tn10)
*Ω = a genetic construct introduced by a two-point crossover (ΩleuA)
*Δdeleted gene::replacing gene = deletion with replacement (ΔleuA::nptII(Kan) indicates that the leuA gene has been deleted and replaced with the gene for neomycin phosphotransferase, which confers kanamycin-resistance, as oftentimes parenthetically noted for drug-resistance markers)