Charcot-Marie-Tooth Disease
Affected Genes: MTMR13
Inheritance: Autosomal Recessive
Variant(canFam6):
chr21:32647063: C>A
Breed: Miniature Schnauzer
General Information: Charcot-Marie-Tooth Disease (CMT) in dogs is an inherited condition that primarily affects Miniature Schnauzers, manifesting as sensory and motor neuropathies. Dogs with CMT often display early symptoms like megaesophagus, leading to regurgitation, and laryngeal paralysis, which causes noisy breathing and altered barking sounds. The disease might also present with neurological signs such as delayed reflexes, tremors, and muscle weakness, particularly in the hind legs. These symptoms usually appear before the age of two and progress slowly, potentially leading to more severe complications like incontinence and anorexia. Despite its progression, many affected dogs can lead relatively normal lives with proper management of their symptoms.
How to Read Your Dog's Test Results for this Genetic Variant:
Two Variants Detected: Dog Likely Affected
One Variant Detected: Dog Unlikely Affected
No Variants Detected: No Effect
Gene / Testing Information: Genetic testing for Charcot-Marie-Tooth Disease (CMT) in dogs targets the SBF2/MTMR13 gene to determine carrier status. CMT is transmitted via an autosomal recessive pattern, necessitating two copies of the mutated gene—one from each parent—for a dog to express the disease. Dogs carrying a single copy of the gene (heterozygotes) do not show symptoms but can pass the mutation to their offspring. A litter from two carrier parents has a 25% chance of being affected, a 50% chance of being carriers, and a 25% chance of being unaffected. Responsible breeding practices supported by reliable genetic testing are crucial to prevent the propagation of this mutation. It is recommended not to breed carriers together to reduce the risk of producing affected offspring.
References:
Farré Mariné, A, Granger, N, Bertolani, C, Mascort Boixeda, J, Shelton, GD, Luján Feliu-Pascual, A. Long-term outcome of Miniature Schnauzers with genetically confirmed demyelinating polyneuropathy: 12 cases. J Vet Intern Med. 2020; 34:2005-2011.
Granger N, Luján Feliu-Pascual A, Spicer C, Ricketts S, Hitti R, Forman O, Hersheson J, Houlden H. Charcot-Marie-Tooth type 4B2 demyelinating neuropathy in miniature Schnauzer dogs caused by a novel splicing SBF2 (MTMR13) genetic variant: a new spontaneous clinical model. PeerJ. 2019 7: e7983