what are her chances

My granddaughter will be 2 in feb.2010. She had been diagnosed with atonic & myoclonic seizures before she was 1 yr. young. I have done research and beleive that she also has childhood absence. We have not had much luck with medication, she has been on so many for her tiny body. She is going to have gene tests done now as the docs cannot give us a reason as to why this has happened. Through my research, i am led to beleive that she has lennox-gastaut syndrome. It is not confirmed, yet. If this turns out to be the case, what are her chances of survival.