>The real question is how "infinitesimal" is that amount of DNA transference, if any, and can it down the line create problems for these patients.<
There is no "transference" insofar as goat DNA getting into human DNA. The DNA infused into the bloodstream will not enter cells, for all practical purposes.
Anyone who has had a single steak in their lifetime will have consumed more "animal" DNA than if they were on a continuous Atryn drip for the rest of their life.
Also note the digestive tract does not figure into the supposed risks posed by DNA contamination in the Atryn preparation.