Which symbol indicates a wild-type allele?

TAnswer:

The wild-type allele of a any gene is indicated by + as superscript to the mutant symbol. For example: the wild-type allele of the Pax1 gene is Pax1+.

Explanation:

The allele that encodes the phenotype most common in a particular natural population is known as the wild type allele ... It is often designated, in genetic shorthand, as "+". For example, Wild type tigers have orange fur and black stripes. One mutation prevents the deposition of the orange/brown pigment, and the result is a "white tiger" that still has dark stripes. A different mutation prevents any melanin (brown pigment) from forming at all, and the result is an albino tiger.