I never thought I would be so happy to have any of my children official diagnosed with anything. However, when it seemed my first born was following in the long tradition of suffering from the "family curse," I felt the need to get it documented as soon as possible. Better heads up for the school, for one. Easier for the rest of the family to understand and accept, for another. The biggest reason? So she could begin to accept it, learn to live with it, adapt around it, and grow successfully inspite of it.
I knew having children brought on the gamble of passing it on. But it's not all bad. Many very iconic individuals had the same thing. Difference being, we live in a time where more is known about it, less of a stigma surrounds it, and most importantly, she'll know early on. That's something none of them had... a head start.
She'll be ok.