Deaf people's disadvantage is an innate property of being deaf.

I disagree that there can be innate disadvantages, except for to the extent the utility function addresses those properties directly. See:

St Addahad's Symptoms. A small group of symptoms including fleshy growths, nerve clusters and neural pathways which result in a near permanent state of distraction as patterns of air pressure change are translated into thoughts and inserted into the mind with disruptively high priority. "Sounds" from all around, indoors and out, near and far, from nearby footsteps to distant thunderstorms or even one's own bodily functions all combine to make a state of prolonged focus nearly impossible to achieve, though this ability can be regained somewhat with practise.

As with many curses, St Addahad's sufferers describe benefits as well, such as being able to know things are happening without needing to see them, and to know which direction they are happening in, and some even report being able to balance without handholds. These trivial sounding benefits appear so addictive that most refuse to be treated. Efforts are underway to cause the onset of these symptoms by technological means, but there is debate on the moral issue of such experiments on humans as the necessary interventions cannot wait until the age of consent.

Can you explain why you believe that makes a moral difference?