Sensory ataxic neuropathy (SAN) is a recently identified
neurological disorder in Golden Retriever dogs with onset during
puppyhood. Affected dogs move in an uncoordinated manner and
have sensory deficits. Researchers from the Swedish University
of Agricultural Sciences, Uppsala University and the Karolinska
Institutet have now revealed that SAN is caused by a mutation in
mitochondrial DNA. The study is published May 29 in the open-
access journal PLoS Genetics. The researchers were able to trace
back all affected offspring on the maternal side, over more than
10 generations, to a female that lived during the 1970s. This
implied a maternal inheritance, which was confirmed by the
identification of a one base pair deletion in the mitochondrial
tRNA-Tyr gene. Further analyses revealed that the mutation leads
to mitochondrial dysfunction, which in turn causes a progressive
loss of neurons. The researchers showed that about five percent
of the current Swedish Golden Retriever population carries the
mutation causing