Quick Summary
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Phenotype: Affected dogs present with early onset neuromuscular weakness developing as early as the first 6 months of life. Clinical signs may include variable degrees of weakness, exercise intolerance (getting tired easily), difficulty swallowing, enlarged esophagus (resulting in vomiting or regurgitation), and difficulty breathing.
Mode of Inheritance: Autosomal dominant (MPZ variant), Autosomal recessive (MTMR2 & SH3TC2 variants)
Alleles: N = Normal, MPZ = MPZ variant, MTMR2 = MTMR2 variant, SH3TC2 = SH3TC2 variant
Breeds appropriate for testing: Golden Retriever and Golden Retriever crosses
Explanation of results:
• Dogs with N/N genotype will not have these inherited forms of congenital hypomyelinating polyneuropathy and cannot transmit these alleles to their offspring.
• Dogs with MPZ/N genotype will likely develop congenital hypomyelinating polyneuropathy and may transmit this MPZ allele to 50% of their offspring. Offspring receiving the allele will also be affected by this inherited form of congenital hypomyelinating polyneuropathy.
• Dogs with N/MTMR2 genotype will not be affected by this inherited form of congenital hypomyelinating polyneuropathy but are carriers. They may transmit this MTMR2 allele to 50% of their offspring. Matings between two carriers are predicted to produce 25% of affected puppies.
• Dogs with N/SH3TC2 genotype will not be affected by this inherited form of congenital hypomyelinating polyneuropathy but are carriers. They may transmit this SH3TC2 allele to 50% of their offspring. Matings between two carriers are predicted to produce 25% of affected puppies.
• Dogs with MPZ/MPZ genotype will likely develop congenital hypomyelinating polyneuropathy and will transmit this MPZ allele to all their offspring. Breeding this dog will result in all offspring being affected by this inherited form of congenital hypomyelinating polyneuropathy.
• Dogs with MTMR2/MTMR2 genotypes will likely develop congenital hypomyelinating polyneuropathy and will transmit this MTMR2 allele to all their offspring.
• Dogs with SH3TC2/SH3TC2 genotypes will likely develop congenital hypomyelinating polyneuropathy and will transmit this SH3TC2 allele to all of their offspring.
Golden Retriever Health Panel
$135 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
Congenital hypomyelinating polyneuropathy (HPN) in the Golden Retriever is an inherited neuromuscular disorder that exclusively affects the peripheral nervous system (i.e., parts of the nervous system that are outside the brain and spinal cord). The condition results from an underproduction of myelin, a protein that surrounds the nerve fibers to help electrical signals travel faster and more efficiently, much like insulation along electrical wires. Myelin is essential for the proper functioning of nerve fibers, and reduced myelination (insulation) of the nerve fibers results in slow responses to stimuli and weakness.
Three variants have been identified as likely causative of HPN in Golden Retrievers: an autosomal dominant missense variant in the myelin protein zero (MPZ) gene (c.Ile145Thr); an autosomal recessive splice site variant in the myotubulin-related protein 2 (MTMR2) gene (c.1479+1G>A); and an autosomal recessive nonsense variant in the SH3 domain and tetratricopeptide repeats 2 (SH3TC2) gene (p.Arg642∗) that results in a much shorter protein than normal.
Affected dogs may display variable degrees of weakness, exercise intolerance (getting tired easily), difficulty swallowing, enlarged esophagus (resulting in vomiting or regurgitation), and difficulty breathing. All four cases described in the publication that first identified these genetic variants were euthanized due to poor quality of life.
Testing recommendations: Testing for HPN assists owners and breeders in identifying affected and carrier dogs. Dogs with one copy of the MPZ allele will be affected. Breeding a dog with one copy of MPZ will result in 50% of offspring being affected by this neuromuscular disorder.
Dogs with one copy of the MTMR2 or SH3TC2 alleles are normal but are carriers. They will pass on the disease alleles to 50% of their offspring. Matings between two carriers are predicted to produce 25% of affected puppies. Breeders can use results from the test as a tool for selection of mating pairs to avoid producing dogs affected by this neuromuscular disorder.