Quick Summary
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Phenotype: Narcolepsy is a sleeping disorder commonly characterized by daytime sleepiness, fragmented sleep patterns, and sudden, transient episodes of muscle weakness or paralysis triggered by play or food. Signs appear suddenly, recovery from them is spontaneous, and there is usually no progression in severity of signs after the dog’s first year.
Mode of Inheritance: Autosomal recessive
Alleles: N = Normal/Unaffected, NAL = Labrador Retriever narcolepsy variant
Breeds appropriate for testing: Labrador Retriever, Labradoodle
Explanation of Results:
- Dogs with N/N genotype will not have this inherited narcolepsy and will not transmit this narcolepsy variant to their offspring.
- Dogs with N/NAL genotype will not have this inherited narcolepsy, but are carriers. They will transmit this narcolepsy variant to 50% of their offspring. Matings between two carriers are expected to produce 25% narcolepsy-affected puppies.
- Dogs with NAL/NAL genotype will develop this inherited narcolepsy and will transmit this narcolepsy variant to all of their offspring.
Results of this test can be submitted to the OFA (Orthopedic Foundation for Animals)
Labrador Retriever Health Panel 1
$165 per animal
Labrador Retriever Health Panel 2
$180 per animal
Sample Collection
Dog DNA tests are carried out using cells brushed from your dog's cheeks and gums. The preferred cytology brushes are sent to you by mail, or you may provide your own brushes. For accepted alternative brushes, click here
We recommend waiting until puppies are at least three weeks old before testing.
Step-By-Step:
- Make sure the dog has not had anything to eat or drink for at least 1 hour prior to collecting sample.
- When swabbing puppies, isolate each puppy from the mother, littermates and any shared toys for 1 hour prior to swabbing. Puppies should not have nursed or eaten for 1 hour prior to collecting sample.
- If collecting samples from more than one dog, make sure to sample one dog at a time and wash your hands before swabbing another dog.
- Label brush sleeve with name or ID of dog to be sampled.
- Open brush sleeve by arrow and remove one brush by its handle.
- Place bristle head between the dog’s gums and cheek and press lightly on the outside of the cheek while rubbing or rotating the brush back and forth for 15 seconds.
- Wave the brush in the air for 20 seconds to air dry.
- Insert brush back into sleeve.
- Repeat steps 5 - 8 for each unused brush in sleeve on a fresh area of cheek and gums. Make sure to use and return all brushes sent by the VGL. In most cases, it will be 3 brushes per dog. If using interdental gum brushes, please note that the VGL requires 4 brushes per dog and only moderate or wide interdental gum brushes are accepted.
- Do not seal brushes in sleeve.
- Place all samples in an envelope and return to the address provided.
ATTENTION:
- Do not collect saliva/drool – the key to obtaining a good sample is getting cheek cells on the swab
- Do not rub swab on the dog’s tongue or teeth – this will result in poor quality sample
- Do not collect a sample from a puppy that has recently nursed – the mother’s genetic material can rub off on the puppy’s mouth and contaminate the sample
Narcolepsy is a disabling neurological disorder that has been identified in several dog breeds, including the Labrador Retriever. This disease affects the brain’s ability to control sleep-wake cycles. It is characterized by daytime sleepiness, erratic sleep patterns, fast transition to rapid eye movement (REM) sleep, and sleep paralysis, but the most striking symptom is cataplexy – sudden loss of muscle tone and collapse without loss of consciousness – which can be triggered by strong positive emotional stimulus such as play or food. Usually, signs appear between 4 weeks and 6 months of age and severity increases until animals are approximately 1 year old, when progression stops.
Narcolepsy in Labrador Retrievers is caused by a single nucleotide change (or SNP) in the Hypocretin Receptor 2 (HCRTR2) gene that causes exon-skipping and produces an abnormal protein. The G to A substitution in the 5’ splice site causes the deletion of exon 6 which, in turn, produces a truncated HCRTR2 protein (330 amino acids instead of the normal 444 amino acids) that cannot properly regulate sleep-wake cycles in affected dogs. The mode of inheritance for this disease is autosomal recessive, which means that males and females are equally affected and that two copies of the mutation are needed to cause narcolepsy. Screening of a random set of Labrador Retrievers at the VGL determined that the HCRTR2 disease allele is rare in this breed, with frequency less than 1%.
Testing for narcolepsy in Labrador Retrievers assists clinicians with diagnosis of narcolepsy and helps breeders identify carriers among breeding stock and select appropriate mates to reduce the risk of producing affected offspring. In order to avoid the possibility of producing affected puppies, matings between known carriers are not recommended.
