Looking for a story

I looking for a story. Here is what I remember about it.

The story involves superheros/mutants.
The main charactor is a mutant with what he considers a minimal power.
His power is to taste/read any DNA around him.
His granddaughter is in a coma (accident?)
He becomes a female to rebirth his granddaughter.

I would appreciate any help in finding this story.

Thank you,
Rachel