Diana, as these dogs express a completely different color opposed to the ones a yorkshire terrier should have, they should be a different breed, and be admired based on this trait.
Take for example Norwich and Norfolk terriers. Their only difference is their ears, even though they both came from the same stock. DNA testing just traces the ingredients used, not desirable traits.
Again, color and texture in Yorkies are of ultimate importance.
Thank you all for your input in the subject
