Answer: What you describe is considered a sport. It is simply a branch that is missing some of the DNA from the parent plant. If you were to attempt to propagate this sport, you may end up with an all white shrub, but it is more likely that the shrub will either revert to the orignal (variegated) coloration, or turn completely green. Might be an interesting experiment, though. If it were my plant, I'd cut the branch off to make room for more variegated foliage. Best wishes with your garden!
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