I don't believe in the "science" of MARS testing for any breed or mix. Period. I never tested my biewers...but know others which did when the test was originally offered. Saluki came back as a result and basset hound in another. The test can only determine within 3 generations. I've seen some biewers with large ears...but not basset hound size. This was one test result. There are others just as off the wall.
MARS also communicated the test is fallible to AKC. Scroll down to page 4 regarding a request by the parent club of Norwich terriers.
https://images.akc.org/pdf/board_minutes/0712.pdf
I know people which knew the two breeds behind their mixed breed litters...and the results were no where close.