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Laryngeal paralysis and polyneuropathy (LPPN)
| Acronym: | LPPN |
| Gene: | CNTNAP1 |
| Mutation: | c.2810G>A |
| Inheritance: | Autosomal Recessive |
| Sample type: | CHS (Cheek Swab), WBE (Whole Blood EDTA) |
Genetics and characteristics
Laryngeal paralysis and polyneuropathy (LPPN) is an inherited neurodegenerative disease that affects specific breeds of dogs. LPPN affects motor, sensory and autonomic peripheral nerves and the age of onset varies, but it usually occurs in geriatric dogs of larger breeds like Leonbergers, Saint Bernards and Labrador retrievers. Breathing difficulties are the prominent symptom of LPPN while other symptoms occur variably across different breeds. These other symptoms include: difficulty swallowing, changes in barking frequency and quality, high-stepping and uncoordinated gait, stumbling, tripping, excercise intolerance and limb muscle atrophy. LPPN is caused by a genetic missense mutation in the CNTNAP1 gene that encodes the contactin-associated protein 1 important for the organization of myelinated axons. The mutated variant of the protein cannot maintain myelin sheats on the axons of peripheral nerves.
LPPN is an autosomal recessive trait, which means that two copies of the mutation are required for a dog to develop the disease. Dogs carrying only one copy of the mutated gene will not develop the disease but act as carriers that can potentially pass the mutated gene to their offspring. The disease is progressive, worsens the quality of life of affected dogs, but it is usually not lethal. LPPN is incurable but certain aspects like laryngeal paralysis can be managed with medication or surgery. Early detection by genetic testing can identify dogs that carry the mutation and inform the breeders decisions when selecting mating pairs.
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:
Letko A, Minor KM, Friedenberg SG, Shelton GD, Salvador JP, Mandigers PJJ, Leegwater PAJ, Winkler PA, Petersen-Jones SM, Stanley BJ, Ekenstedt KJ, Johnson GS, Hansen L, Jagannathan V, Mickelson JR, Drögemüller C. A CNTNAP1 Missense Variant Is Associated with Canine Laryngeal Paralysis and Polyneuropathy. Genes (Basel). 2020 Nov 27;11(12):1426. doi: 10.3390/genes11121426.
Monnet E. Surgical Treatment of Laryngeal Paralysis. Vet Clin North Am Small Anim Pract. 2016 Jul;46(4):709-17. doi: 10.1016/j.cvsm.2016.02.003. Epub 2016 Mar 4.