Medical miracle?

Just as I was raving on about how God cannot be proven. This is a rather agnostic observation, it seems, and agnosticism is something that Michelle has been talking about recently, everytime we talk about belief and faith. But perhaps it's true, I am agnostic. But that's another story for another day.

For now there is another story. An Australian girl has adopted the immune system of her liver donor. How did that happen?

http://www.channelnewsasia.com/stories/afp_asiapacific/view/324634/1/.html

Is this a medical miracle? What caused it? Just a chance development? Or is it God showing that something that wasn't even in the imagination of man is actually possible?