According to Cornell the gene is mutated in the Amstaffs and for what ever reason they have not found the DNA marker for CRD1 for the Amstaffs as of yet. Amstaff breeders need to test their dogs and send in affected dogs for research. Optigen also offers free testing for affected dogs.
Researchers were somewhat surprised to learn that this mutation was not the cause of a very similar disease that occurs in a closely related breed, the American Staffordshire Terrier (Am.Staff.). The Am.Staff.’s disease has been termed Cone Rod Dystrophy 1 (crd1) and is currently being molecularly characterized. Because Pit Bulls and Am. Staffs share many common ancestors and interbreeding among these and other bull-type dogs is quite common, OptiGen will accept samples from any of the “bull” breeds for crd2 testing.
President Evergreen State APBT Club