Inflammatory myopathy (IM)

Inflammatory myopathies are a large group of disorders characterized by infiltration of inflammatory cells into muscle. \nFive related Dutch Shepherd dogs have been found to suffer from an inflammatory myopathy with generalized muscle weakness and severe muscle atrophy. Due to the early onset of the symptoms and the presence of related affected dogs, a genetic cause was suspected. A genetic variant in the SLC25A12 gene, which encodes for a mitochondrial aspartate-glutamate transporter (AGC1), has been found to correlate with the symptoms of the disease. Due to the variant, the transporter shows a decreased transport activity and therefore a proinflammatory milieu and oxidative stress in muscles. \nTypical symptoms are muscle tremors, stiff short-strided gait and weakness progressing to inability to walk, beginning at 3 to 9 months of age. Serum CK activities (a marker of muscle damage) is persistently elevated at affected dog. Dogs were euthanized by 2 years of age because of the progression of weakness. \nThe described variant has neither been found in Dutch Shepherd related breeds, like Belgian Shepherds or German Shepherds, nor in other unrelated breeds other than the Dutch Shepherd, so far. \n