Genetic basis of CNM in Labrador Retrievers - is caused by a mutation in the PTPLA gene (protein tyrosine phosphatase-like member A). PTPLA codes for an enzyme involved in the production of long-chain fatty acids that are important for muscle homeostasis. The mutation leads to a loss of normal PTPLA function, disrupting muscle cell growth and differentiation. CNM follows an autosomal recessive inheritance pattern: dogs must inherit two copies of the mutated gene (CNM/CNM) to be affected; carriers (N/CNM) have one copy and do not show clinical signs but can pass the mutation on.
Pathophysiology - The mutation impairs muscle fiber structure and function, causing generalized loss of muscle tone and muscle weakness. Although the precise role of PTPLA in muscle biology is not fully understood, the mutation affects muscle homeostasis leading to clinical signs.
Complications - CNM usually manifests in puppies between 2 to 5 months of age. Clinical signs include: Generalized loss of muscle tone and control, Exercise intolerance, Awkward, stiff, or "stilted" gait, Muscle weakness and sometimes muscle atrophy.
Why This Matters to Breeders and Vets - Carriers are asymptomatic but breeding two carriers carries a 25% risk of producing affected puppies. Identification of carriers and affected dogs through genetic testing aids in responsible breeding choices. Early identification helps veterinarians diagnose cause of muscle weakness and guide clinical care.
Summary - Centronuclear Myopathy in Labrador Retrievers is a recessive inherited muscle disorder caused by a mutation in the PTPLA gene, leading to muscle weakness and exercise intolerance beginning in puppyhood. Genetic testing is available and critical for identifying carriers and affected dogs to guide informed breeding decisions and reduce disease prevalence.