Encephalopathies include two different SLC19A3 gene variants associated with subacute necrotizing encephalopathy or Leigh syndrome (OMIA#001097-9615), one in Alaskan Huskies [16] and the other in Yorkshire terriers [17]; a cytochrome b variant (OMIA#002684-9615) causing canine spongiform leukoencephalomyelopathy in Australian blue heelers and Shetland sheepdogs [18]; and a NDUFS7 variant (OMIA#002840-9615) in a Jack Russell–Chihuahua mixed-breed dog, the most common gene associated with Leigh syndrome in people [19]. This evidence concerns the gene MT-CYB and Leigh syndrome.