Neuropathy, hereditary sensory and autonomic (congenital insensitivity to pain) (SCN9A-related)

Gene: SCN9A

Transmission: Autosomal recessive

For an autosomal recessive genetic disease an animal must have two copies of the mutation in question to be at risk of developing the disease.  Both parents of an affected animal must be carriers of at least one copy of the mutation.  Animals that have only one copy of the mutation are not at risk of developing the disease but are carrier animals that can pass the mutation on to future generations.

Mutation: Substitution, SCN9A gene: c.2761 C>T, p.(Arg921Cys), Chr.36.

Medical system: Neuropathy, pain perception

Breed: Mixed breed

Age of onset of symptoms: Soon after birth.

Two littermates of mixed dog parentage were presented with physical injuries.  For both animals there was an absence of superficial and deep pain perception over the entire body.  Molecular studies identified a mutation in the SCN9A gene, which codes for a sodium channel protein important for pain perception in humans.  A survey of 926 additional dog genomes failed to reveal additional animals harboring the mutation.  These findings could be useful to veterinarians in cases of unexplained congenital pain insensitivity in dogs, but in general should not be of concern to breeders.

Other neuropathies in dogs involving insensitivity to pain that have been characterized at a molecular level include:

Acral mutilation syndrome (GDNF-related)

Neuropathy, sensory (RETREG1-related), OMIA [2032-9615]

References:

OMIA link: [2616-9615]

Cocostîrc V, Paștiu AI, Pusta DL. (2023) An overview of canine inherited neurological disorders with known causal variants. Animals (Basel) 13:3568.  [38003185]

Gutierrez-Quintana R, Christen M, Faller KME, et al. (2023) SCN9A variant in a family of mixed breed dogs with congenital insensitivity to pain. J Vet Intern Med 37:230-235.  [pm/36330088]

With contributions by: Isabella Drouin and Janik Felcarek-Hope, Class of 2030, Faculty of Veterinary Medicine, University of Montreal.  (Translation: DWS).