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Congenital Myasthenic Syndrome, Labrador Type (CMS-LAB)

Congenital Myasthenic Syndrome Labrador Retriever (CMS-LAB)

Congenital Myasthenic Syndrome (CMS) is an inherited neuromuscular disease that affects signaling at the neuromuscular junction where nerve and muscle cells meet. Symptoms can first be seen in affected dogs typically anywhere from 2 to 12 weeks of age and are characterized by skeletal muscle weakness in all four limbs following rigorous exercise. Affected dogs will typically recover from symptoms following a rest period. Unfortunately, there are no known treatments for CMS.

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These dogs have two copies of the normal gene and will neither develop Congenital Myasthenic Syndrome nor pass this mutation to their offspring.


These dogs have one copy of the normal gene and one copy of the mutation associated with this disease. They will not develop Congenital Myasthenic Syndrome but will, if bred, pass the mutation to 50% of its offspring, on average.


These dogs have two copies of the mutation associated with Congenital Myasthenic Syndrome which will likely result in muscle weakness and collapse following rigorous exercise.

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Additional Details


Autosomal Recessive

Affected gene



Ch. 23


C.1010 T>C


Rinz CJ, Levine J, Minor KM, Humphries HD, Lara R, Starr-Moss AN, Guo LT, Williams DC, Shelton GD, Clark LA. A COLQ missense mutation in Labrador retrievers having congenital myasthenic syndrome. PLoS One. 2014 Aug 28;9(8):e106425. [PubMed: 25166616]