Oculoskeletal Dysplasia (OSD3)

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Geneticists at the Kennel Club genetics centre at the Animal Health Trust have discovered a mutation that causes Oculoskeletal Dysplasia (OSD) in Northern Inuits.  A test for this mutation is available from 24 September 2017

Northern Inuit with Oculoskeletal DysplasiaOculoskeletal Dysplasia is a genetic disease characterised by Skeletal and ocular defects including cataracts, retinal detachment and primary achondroplasia (dwarfism).

We are calling this form of Oculoskeletal Dysplasia, OSD3 to distinguish this from other, genetically distinct forms of OSD in other breeds.

The OSD3 mutation accounts for all the Northern Inuit cases that we investigated during our research.

The mutation that causes OSD3 has only been identified in Northern Inuits to date. However, the possibility that the mutation is present in closely related breeds and Wolfalike breeds cannot be excluded.

How common is the mutation

Our research suggests that up to 15% of dogs carry this mutation while 0.6% will have 2 copies and therefor suffer from OSD.

Please note that as these figures are from the samples submitted for research they may not be representative of the whole Northern Inuit population.

This frequency will be updated once we have tested a high number of dogs.

The mutation that causes OSD3 has only been identified in Northern Inuits to date. However, the possibility that the mutation is present in closely related breeds and Wolfalike breeds cannot be excluded.

Northern InuitHow is the disease inherited?

The OSD3 mutation is recessive; this means that a dog must inherit 2 copies of the mutation, one from each parent, to be clinically affected by OSD.

Individuals with one copy of the defective gene and one copy of the normal gene, called carriers, show no signs of disease but can pass the defective gene onto their offspring.

It is only possible to identify carriers with DNA testing.

When two carriers are crossed, 25% (on average) of the offspring will be affected by the disease, 25% will be clear and the remaining 50% will themselves be carriers.

Breeders using our DNA test will be sent results identifying their dog as belonging to one of three categories.  In all cases the terms ‘normal’ and ‘mutation’ refer to the position in the DNA where this OSD3 mutation is located in the Northern Inuit; it is not possible to learn anything about any other region of DNA from this test.

 

What does the DNA test tell me?

The DNA test for OSD3 identifies if your dog is clear of the mutation, a carrier of the mutation or is affected by the mutation.

CLEAR: These dogs have two copies of the normal gene and will not develop OSD as a result of the OSD3 mutation we are testing for, although we cannot exclude the possibility they might develop a similar condition due to other causes or the effect of other, unidentified mutations

CARRIER: These dogs have one copy of the mutation and one normal copy of DNA. These dogs will not develop OSD themselves as a result of the OSD3 mutation but they will pass the mutation on to approximately 50% of their offspring.

AFFECTED: These dogs have two copies of the OSD mutation and will have OSD caused by this mutation.

We cannot exclude the possibility that carriers might develop a similar condition due to other mutations they might carry that are not detected by this test.

 

Breeding Advice

We recommend that for the first few generations after the development of a DNA test you still breed with carriers to avoid reducing genetic diversity.

Dogs carrying this mutation can be breed from safely to avoid producing affected puppies. Carriers of the mutation should be mated to dogs that have a clear result; such a mating will not produce any puppies affected with OSD

On average, 50% of such a litter will be clear and 50% carriers; there can be no affected dogs produced from such a mating. Please note these percentages apply to a statistically significant number of puppies. The distribution does vary from litter to litter.

Pups which will be used for breeding can themselves be DNA tested to determine whether they are clear or carriers of OSD.

For more information please contact us and we’ll be happy to deal with your enquiry.