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. 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.

Findings indicate the mutation segregates in 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 high frequency within most of the breeds in which it segregates. (Gould et. al, 2011)