PHPT
Below is a link to the UK Kennel Club's list of all Keeshonds registered (or appearing in a UK pedigree) in the UK who have been PHPT tested.
https://www.thekennelclub.org.uk/media/234691/keeshondphptclears.pdf
Tom Lewis: "It is demonstrated in this study that, when ‘hereditary clear’ status is repeatedly assigned over a number of generations, a modest rate of false paternity can result in a notable proportion of ‘hereditary clear’ assignments being false, unless the disease causing mutation frequency is very low."
"In light of these findings and to reduce the risks of producing puppies destined to be affected by such diseases, the Kennel Club has determined to limit the assignment of ‘hereditary clear’ status of registered dogs to 2 generations, with effect from January 2022."