Hereditary Cataract in Australian Shepherds

Researchers at the Animal Health Trust found a mutation in HSF4 gene in Australian Shepherds. This gene defect causes hereditary cataract in that specific breed. More information is required of the clinical features of the Australian shepherd cataract but posterior polar cataract seems to be the most common form of cataract found in that breed.

The gene defect is inherited in autosomal dominant fashion. This means that the risk of developing cataract is increased if only one copy of the HSF4 gene has the mutation. Both parents of the HC- dogs do not therefore need to be the carriers of the mutation. The gene defect can also exist in both chromosomes but to develop the disease it is enough to get the mutations from one parent.

If the dog carries one or two copies of the HSF4 mutation it has the risk 11 times higher to develop posterior polar cataract than the dogs that do not carry that specific mutation. The risk number can vary a little as the research continues but the change should not be significant. It is also possible that there are still other unknown genes behind the risk of developing hereditary cataract in Australian shepherds.

If a dog carries one copy of the mutations it can transfer the gene defect to approximately 50% of its offsprings. If the dog has two copies of the mutation it transfers the defect to all of its offsprings. Dogs that carry HSF4 mutations should not be used in breeding.

The test of HSF4 mutation is now available and the instructions of ordering the test and sending DNA samples are found in here. We send the results of the test to the owner/owners of the dog.

The results are reported as follows:

NORMAL: Do not carry HSF4 mutation and has therefore no increased risk of developing posterior polar cataract.

CARRIER (SICK): Carries one copy of the HSF4 mutation and because of the dominant inheritance has therefore a risk 11 times higher of developing posterior polar cataract. Carrier can also transfer the defect to approximately 50% of its offsprings.

SICK: Carries two copies of the HSF4 mutation and has therefore a risk 11 times higher of developing posterior polar cataract than a normal dog. It can also transfer the gene defect to all of its offsprings.