I've been trying to work this out, because it's extremely important to think about queries halfway through one's manuscript...

If you're writing a novel the focuses on a character's cancer, and you have/had cancer, should you say that in the query?

Likewise, if you've written a novel with a bipolar/ schizophrenic/ autistic/ otherwise DMSable situation, and you yourself share that condition, should you mention it?

I can think of a fairly equal number of pros and cons for both stating it and omitting it in the query, but I can't decide which would be the most effective thing to do to get an agent to want to read more.