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Narcolepsy (Labrador Retriever Type)

Narcolepsy (NA) (Labrador Retriever Type) is an inherited sleep disorder in Labrador Retrievers, characterized by excessive daytime sleepiness and sudden episodes of muscle weakness or paralysis triggered by excitement.

Affected Genes: HCRTR2

Inheritance: Autosomal Recessive

Variant(canFam6):
chr12:22511327: G>A

Breed: Australian Cobberdog
Australian Labradoodle
Labradoodle
Labrador Retriever
UK Breed Council Labrador Retriever

General Information: Narcolepsy (NA) (Labrador Retriever Type) is a hereditary sleep disorder affecting Labrador Retrievers, marked by excessive daytime sleepiness and sudden, transient episodes of muscle weakness or paralysis, often triggered by excitement such as play or food. Affected dogs typically show symptoms between one to six months of age, including an inability to stay awake for extended periods and episodes of collapse and sleep following positive stimulation. During these episodes, dogs experience a sudden loss of muscle tone and appear uncontrollably sleepy, though they may not always completely fall asleep. Symptoms usually stabilize after the dog's first year and do not progress in severity. Importantly, affected dogs do not have other associated health problems.

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 Narcolepsy (NA) (Labrador Retriever Type) involves screening for mutations in the HCRTR2 gene to determine carrier status. This disorder is inherited in an autosomal recessive manner, meaning a dog must inherit two copies of the mutated gene, one from each parent, to develop the condition. Carriers of the gene mutation do not typically exhibit symptoms but can pass the mutation to their offspring. When two carriers are bred, each puppy has a 25% chance of being affected and a 50% chance of being a carrier. To prevent producing affected puppies and eliminate the mutation from breeding lines, it is crucial to avoid breeding two carriers. Dogs that are not carriers of the mutation do not pose a risk of producing affected puppies, making genetic testing an essential tool in responsible breeding practices.

References:
Chen L, Brown RE, McKenna JT, McCarley RW. Animal models of narcolepsy. CNS Neurol Disord Drug Targets. 2009 8(4):296-308.

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 11(4):531-539.

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 98(3):365-376.