My sister-in-law has it and yes, her fingers will turn white, hurt, and tingle. She has lots of pairs of gloves and drinks lots of warm liquids in the winter where she can wrap her fingers around the mug to help them stay warm.

I said some prayers for your friend's DD. I hope they can find something that will help her. I know my SIL is mostly effected in the winter but in the summer she gets bouts of it when she is inside in a/c. While it keeps her cool, the temperature is too low for her hands, if that makes sense. So, it makes sense to me that your friend's DD would have trouble even in the summer.