I say go for it, while I also agree with Gaz. and Kitty and Ali ... all depends on the specific person.

Once in a great while, I'll be standing around with a group of moms, waiting for something... and the talk of great woes of hurts and illnesses go on and on... when it gets to be too much, and I'm tired of nodding along I'll pipe up (in a small voice) and say something like... 'well, i'm glad they have a cure for that, cause they don't for me' ... and go on to say, 'I have a disease that doesn't have a cure because they don't know the cause. I have MS.'

And then walk away

Niko