Both clinically rare and of complex inheritance. Test is considered poorly correlated with risk for development of DM, and recommendations are to not use the test for breed-wide breeding strategies, even where there is some evidence of the presence of DM in the breed. While the SOD 1 variant may be commonly found across many breeds, there are few clinical cases observed and confirmed, and in many cases DM has never been observed in the breeds.

Multiple research sources indicate that this form of PRA-prcd could be present in many breeds, and testing could be relevant widely across a large number of different breeds of dog, many of which are terriers or breeds with terrier co?ancestry, but some of which have more diverse origins. Research indicates that the mutation is present at varying breed-specific frequency, but that testing and applying the test results can lead to signifigant reduction in the disease.