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Sensory Neuropathy Border Collie Type (SN)
| Acronym: | SN |
| Gene: | FAM134B |
| Mutation: | g.80439639_86910352inv |
| Inheritance: | Autosomal recessive |
| Sample type: | CHS (Cheek Swab), WBE (Whole Blood EDTA) |
Genetics and characteristics
Sensory neuropathy Border Collie type is an inherited progressive neurological disorder that affects the Border Collie breed. Generally, neuropathy is a disease of the peripheral nerves. The peripheral nervous system is responsible for sensation feeling to the skin and muscle control. The disease of the sensory nerves causes sensory neuropathy. Sensory neuropathy can be divided into two groups, inherited or acquired through disease processes or trauma. Inherited sensory neuropathy is a rare disorder but has been reported in several countries worldwide. Except in Border collies, the disorder has been diagnosed also in Brittany spaniel, Welsh corgis, and Siberian huskies. Inherited forms of sensory neuropathy are suspected to affect also shorthaired pointers, English pointers, longhaired dachshunds, and a Jack Russell terrier. Cases of acquired sensory neuropathies have been described in a Siberian husky, Doberman, whippet, Scottish terrier, and golden retriever. Affected dogs start to show symptoms between the ages of 5 and 7 months. Clinical signs include loss of coordination, joint laxity, loss of proprioception (lack of awareness of where the limbs are in space), and inability to perceive pain. Affected dogs often have self-mutilated limbs, which may be due to tingling or pain in their paws, another manifestation of the disorder. Since the disorder is progressive and the symptoms are severe, affected dogs are usually euthanized.
Sensory neuropathy in Border collies is caused by a mutation in the FAM132B gene, which encodes a Golgi protein found in sensory and autonomic ganglion neurons. The complete role of this gene remains unclear, but it has been confirmed that the gene is crucial in the survival of the sensory nerve cells. The disorder is inherited in an autosomal recessive pattern. A dog can be clear, carrier, or affected. Carriers of the gene are heterozygous and do not develop the disease’s symptoms. When mating two carrier dogs, each future cub has a 25% chance of being affected, a 50% chance of being an asymptomatic carrier, and a 25% chance of being unaffected and not a carrier.
Results Reported As
Test Result |
Interpretation of test result |
CLEAR |
Tested mutation was not detected in animal with „clear“ result. Animal tested as clear has wild-type allele in homozygous state (i.e. two pairs of healthy alleles). It will not develop disease caused by tested mutation.* It will pass only wild-type allele to its offspring. |
CARRIER |
Tested mutation was detected in animal with „carrier“ result. Animal tested as carrier has one wild-type and one mutation allele, it is in heterozygous state. It will not develop disease caused by tested mutation.* It can pass wild-type or mutation allele to its offspring. |
AFFECTED |
Tested mutation was detected in animal with „affected“ result. Animal tested as affected has two copies of mutation alleles affecting the gene. It is likely the animal will experience a genetic disorder due to this mutation.** It will pass only mutation allele to its offspring. |
*Test excludes only tested mutation but not possible unknown mutations or factors that can lead to similar condition/symptoms.
** Potential unknown mutations or multiple other factors can possibly affect the likelihood of experiencing a genetic disorder.
References:
Forman OP, Hitti RJ, Pettitt L, Jenkins CA, O’Brien DP, Shelton GD, Risio LD, Quintana RG, Beltran E, Cathryn Mellersh. An inversion disrupting FAM134B is associated with sensory neuropathy in the Border Collie dog breed. G3 (Bethesda). 2016 Sep 8;6(9):2687-92.