Narcolepsy (Labrador Retriever Type)

Affected Genes: HCRTR2
Inheritance: Autosomal Recessive
Mutation: chr12:22620881 (canFam3): G>A

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Common Symptoms

Narcolepsy (Labrador retriever type) is an inherited disorder affecting Labrador retrievers. Dogs with the inherited form of narcolepsy typically present between one to six months of age with an inability to stay awake for extended periods of time and episodes of collapse and sleep following positive stimulation such as play or food. Affected dogs fall asleep faster than normal dogs and appear sleepy more frequently. During episodes of collapse dogs have a sudden loss of muscle tone and appear uncontrollably sleepy but may or may not completely fall asleep. Symptoms do not progress after one year of age and affected dogs do not have other associated health problems.

Breed-Specific Information for the UK Breed Council Labrador Retriever

The Mutation of the HCRTR2 gene associated with narcolepsy (Labrador retriever type) has been identified in Labrador retrievers, although its overall frequency in this breed is unknown.

Testing Tips

Genetic testing of the HCRTR2 gene in Labrador retrievers will reliably determine whether a dog is a genetic Carrier of narcolepsy (Labrador retriever type). Narcolepsy (Labrador retriever type) is inherited in an Autosomal Recessive manner in dogs meaning that they must receive two copies of the mutated gene (one from each parent) to develop the disease. In general, carrier dogs do not have features of the disease but when bred with another carrier of the same Mutation, there is a risk of having affected pups. Each pup that is born to this pairing has a 25% chance of inheriting the disease and a 50% chance of inheriting one copy and being a carrier of the HCRTR2 gene mutation. Reliable genetic testing is important for determining breeding practices. In order to eliminate this mutation from breeding lines and to avoid the potential of producing affected pups, breeding of known carriers to each other is not recommended. Labrador retrievers that are not carriers of the mutation have no increased risk of having affected pups.

There may be other causes of this condition in dogs and a normal result does not exclude a different mutation in this gene or any other gene that may result in a similar genetic disease or trait.

References

  • Chen L, Brown RE, McKenna JT, McCarley RW. Animal models of narcolepsy. CNS Neurol Disord Drug Targets. 2009 Aug;8(4):296-308. [PubMed: 19689311]
  • Hungs M, Fan J, Lin L, Lin X, Maki RA, Mignot E. Identification and functional analysis of mutations in the hypocretin (orexin) genes of narcoleptic canines. Genome Res. 2001 Apr; 11(4):531-9. [PubMed: 11282968]
  • Lin L, Faraco J, Li R, Kadotani H, Rogers W, Lin X, Qiu X, de Jong PJ, Nishino S, Mignot E. The sleep disorder canine narcolepsy is caused by a mutation in the hypocretin (orexin) receptor 2 gene. Cell. 1999 Aug 6; 98(3):365-76. [PubMed: 10458611]