Would you please tell me a little about yourself?
This should be answered simply, and you should state not only why you want this position but also why you're leaving your current position. Even if they don't ask the latter, they will want to know, so proactively you should state why.
Our sample answer is from someone with gaps in his/her professional path.
"I am married with two children. After my Internal Medicine residency, I did my endocrinology fellowship for two years. After that, I remained at the school for another year as staff. But now I want more clinical exposure instead of mainly academic, so that is why I'm applying here now."