Do you think I should tell a potential employer I have turner syndrome?

No. In my opinion, there is no reason for you to disclose any health issues to a prospective employer unless there is a very real possibility that a health issue would impact your ability to carry out the duties of the position. If there is any question about that, review details of the americans with disabilities act to see what your legal rights are.
No Reason To. Unless you have conditions affecting health and performance such as heart defects, I do not see any reson to mention it. If your health insurance requires that info, a different story.