Though not completely applicable, I am using my knowledge of snake genetics (ball pythons) to understand this chick and that is why I'm thinking it is Leucistic.
I also know of a case where two cousin Servals were bred and produced Leucistic offspring. And of course there are white lions and tigers produced the same way.
I also know of a case where two cousin Servals were bred and produced Leucistic offspring. And of course there are white lions and tigers produced the same way.