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Myeloperoxidase Deficiency

Myeloperoxidase Deficiency is a condition causing an increased susceptibility to fungal and bacterial infections. This is due to a defect of an important enzyme present in the white blood cells of the immune system.

Key Signs

Susceptibility to fungal and bacterial infections

Age of Onset

At birth

Present at birth


Autosomal Recessive

For autosomal recessive disorders, dogs with two copies of the variant are at risk of developing the condition. Dogs with one copy of the variant are considered carriers and are usually not at risk of developing the disorder. However, carriers of some complex variants grouped in this category may be associated with a low risk of developing the disorder. Individuals with one or two copies may pass the disorder-associated variant to their puppies if bred.

Likelihood of the Condition

High likelihood

At risk dogs are highly likely to show signs of this disease in their lifetime.

What to Do

Here’s how to care for a dog with Myeloperoxidase Deficiency

Partner with your veterinarian to make a plan regarding your dog’s well-being, including any insights provided through genetic testing. If your pet is at risk or is showing signs of this disorder, then the first step is to speak with your veterinarian.

For Veterinarians

Here’s what a vet needs to know about Myeloperoxidase Deficiency

Affected dogs are usually clinically normal though an increased susceptibility to infections, especially fungal and bacterial infections, has been associated with the disease. The disease might also predispose an affected dog to neoplastic and neurodegenerative changes. The disease is caused by the deficient or absent function of the myeloperoxidase enzyme in neutrophils and monocytes.

Therapy is targeted at treating the secondary infections.

For Breeders

Planning to breed a dog with this genetic variant?

There are many responsibilities to consider when breeding dogs. Regardless of test results it is important that your dog is in good general health and that you are in a position to care for the puppies if new responsible owners are not found. For first time or novice breeders, advice can be found at most kennel club websites.

This disease is autosomal recessive meaning that two copies of the mutation are needed for disease signs to occur. A carrier dog with one copy of the Myeloperoxidase Deficiency mutation can be safely bred with a clear dog with no copies of the Myeloperoxidase Deficiency mutation. About half of the puppies will have one copy (carriers) and half will have no copies of the Myeloperoxidase Deficiency mutation. A dog with two copies of the Myeloperoxidase Deficiency mutation can be safely bred with a clear dog. The resulting puppies will all be carriers. Puppies in a litter which is expected to contain carriers should be tested prior to breeding. Carrier to carrier matings are not advised as the resulting litter may contain affected puppies. Please note: It is possible that disease signs similar to the ones caused by the Myeloperoxidase Deficiency mutation could develop due to a different genetic or clinical cause.

Technical Details

Gene MOP
Variant C>T
Chromosome 9
Coordinate 32,929,382

All coordinates reference CanFam3.1

References & Credit

Credit to our scientific colleagues:

Gentilini, F., Zambon, E., Mancini, D., & Turba, M. E. (2016). A nonsense mutation in the myeloperoxidase gene is responsible for hereditary myeloperoxidase deficiency in an Italian hound dog. Animal Genetics, 47(5), 632–633. View the article