In regards to breeding, if wanting to breed a dog and it has focal and/or multi-focal folds, test for RD/OSD. If clear, the dog may receive a CERF number. If the dog is a carrier, it cannot receive a CERF number. A RD/OSD carrier could be bred to a dog that has been genetically tested clear. But there will be some carriers produced and some or all carriers will likely have folds too. It would be unwise to breed a carrier to a dog that has not been genetically tested, because reportedly (Optigen website) some carriers don't have retinal folds. So a clear CERF does not necessarily mean clear of RD/OSD.