Centronuclear myopathy Labrador Retriever type (CNM)
Centronuclear myopathy Labrador Retriever type (CNM) is inherited congenital disorders characterized by an excessive number of internalized nuclei. This causes insuficient muscle function in Labrador Retrievers. At first, puppy will seem normal, but with puppy’s aging, Labrador Retriever Centronuclear myopathy symptoms starts to show. Within 2 to 5 months clinical features in pups will include hypotonia, generalized muscle weakness, abnormal postures, stiff hopping gait, exercise intolerance and increased collapse when exposed to cold. On examination, there is evidence of skeletal muscle atrophy, particularly involving muscles of the head and tendinous areflexia. Histopathological evaluation of muscle biopsies demonstrates a characteristic centralization of myonuclei, often located in areas devoid of myofibrils with mitochondrial aggregation. No cure for centronuclear myopathy has been developed and affected dog will never develope properly functioning muscle tissue. Dog can live normally, but limited and affected by symptoms of centronuclear myopathy.
Labrador Retriever Centronuclear myopathy is inherited in a recessive manner, meaning the puppy must carry two copies of the defective gene in order to be affected by the disease. This means than a dog can also be a carrier for the disease, without showing the Centronuclear myopathy symptoms.
Pelé, M., Tiret, L., Kessler, J.-L., Blot, S., and Panthier, J.-J. (2005). SINE exonic insertion in the PTPLA gene leads to multiple splicing defects and segregates with the autosomal recessive centronuclear myopathy in dogs. Human Molecular Genetics 14, 1417–1427.