This basically falls under the same category as a photograph. Your potential employer doesn't need to know your hair color, height or weight, or ethnicity. They don't need to know about any disabilities you have. Not only do they not need to know, they really don't want to know, because they're legally prevented from discriminating against disabled people.
There are a few exceptions, jobs for which certain physical attributes are a necessary part of getting the job done (think actors or prison guards in certain situations). In legal terms, this is known as a bona fide occupational qualification (BFOQ). If the employer specifically asks for this information because of a BFOQ, you should provide it. However, most employers will not, and will address the matter during the interview.