Are white birthmarks a sign of seizures?

My daughter is almost two and was born with probably two white 'birthmarks'. In the last two years she has developed two or three more. They are flat and pale white. She has one larger one that she has always had that is in her waist line near her bottom, one smaller one above that, more on her lower back, one on her belly, and two or three on her legs. I once heard that that could be a sign of seizures. Any info would be wonderful!!