Can Seizures Occur With Change In Altitudes?

I have a daughter that is 23, in Grand Lake, CO (elevation 8,400 ft), and she had what they think was a seizure. My youngest daughter, 16, started having seizures at age 14, in Grand Lake, CO. We are from St. Joseph, MO, and they have never had a problem at that altitude. How can I be sure of the diagnosis?