I think because of their unique coloring from the German Shepherd a couple of players wanted to breed them seperate from the standard German Shepherd.   I feel like I remember seeing a post about them in the add to breed section somewhere and now I can't find it.

I believe in America, White Shepherds are classified as an actual separate breed because they've been bred so selectively ^^

So I looked it up, and they actually are a recognized separate breed according to the UKC. Also, the white coloration was banned from the GSD breed standard, so that also helps explain why they're separate ^^

https://en.m.wikipedia.org/wiki/White_Shepherd

I am super curious if your mom shows her GSDs that she breeds? The White Shepherd is a seperate breed and I have met a few in person that are shown via UKC shows, they are always so stunning. I am just such a sucker for darker dogs (dark sable gsds = ftw) so I stick to my GSDs on hp.