Some will tell you that White German shepherds are prone to deafness, but I believe that is just a myth. They are also completely different from albinos. They are unacceptable in the AKC show ring, but acceptable in the UKC. The reason for their disqualification is because German shepherds are a herding breed, and a white German shepherd would blend in too well with the sheep, and stand out too much in its environment, where it could be an easy target for wild animals. They can still be registered with the AKC under the color "white". One of the earliest German shepherds was white, and a prominent dog to the development of the breed and sired many working German shepherds. I don't know much about breeding, but from what I understand it's a recessive gene. A white bred with a sable could have white, sable, and black and tans depending on the genes of each dog. But a white bred with a white will provide an all white litter.
Very beautiful dogs, but I can't say I personally agree with breeding for the white color. Panda shepherds, though, look plain ridiculous in my opinion.