Consumers and breeders serious about canine health should visit this Australian website. Lots of great info on genetic problems seen in purebred dogs.
Holding breeders to a standard is one of the most important ways to reduce animal suffering and consumer fraud.
When you purchase a pup with medical problems whether they are obvious early on or will manifest later in the dog's life, the dog suffers and so does your heart and wallet. ALL consumers who purchase a purebred or "designer" breed (expensive mutts!) should expect a breeder to be able to produce PROOF that their breeding dogs and or pups have been screened for common disorders. Otherwise, what are you paying for??
For more info on genetic problems you may inadvertently purchase if you buy a purebred dog visit http://www.pupquest.org/for-vets.html