Progressive Retinal Atrophy (BBS2 type)

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Find out if your Shetland Sheepdog could develop Progressive Retinal Atrophy (PRA) caused by BBS2 at CAGT.

Categories ,
Turnaround 1-2 weeks
OMIA OMIA002484-9615
Aliases , ,

Results from this test will be reported as detailed in the Registry Reporting list.


Part of the official UK Kennel Club testing scheme in Shetland Sheepdog

Progressive retinal atrophy (PRA) is the most common form of inherited disease affecting the retina in dogs.  Genetically different forms of PRA, caused by mutations in different genes, affect many breeds of dog with each form usually affecting one or a small number of breeds. PRA is characterised by progressive degeneration of the retina at the back of the eye and leads to vision loss and blindness.

A form of PRA in Shetland Sheepdogs is caused by a mutation in a gene called BBS2. In humans, mutations in BBS2 are associated with a condition known as Bardet Biedl syndrome.  This novel form of PRA, is unusual as it presents with other characteristics including a wavy, atypical textured coat, upturned nose and dental defects. There is evidence that this syndrome may also cause kidney abnormalities and obesity due to an enhanced motivation for food, but further studies are required to confirm this. The age of onset of this form of PRA is variable. Dogs that are homozygous for the BBS2 mutation will almost certainly develop PRA during their lifetime and may also display some or all of the other characteristics associated with the syndrome.  Research undertaken by the Kennel Club Genetics Centre indicates approximately 1 in 38 Shetland Sheepdogs are carriers of the BBS2 mutation. There is no cure for PRA but using the DNA test to identify dogs that carry this mutation will prevent further spread of this blinding condition in this lovely breed.

Autosomal Recessive

Our advice is to breed with carrier animals for the first few generations after the development of a DNA test. This ensures that desirable traits in the breed can be captured.

Carriers can be safely bred to clear dogs. On average, 50% of such a litter will be clear and 50% carriers; there can be no affected dogs produced from such a mating.

Puppies which will be used for breeding should themselves be DNA tested to determine whether they are clear or carriers of this PRA mutation.

Gene BBS2
Variant Single base substitution (c.1222G>C)
Assay Type Variant Specific
Inheritance Autosomal Recessive
Severity Moderate: Affected animals experience significant discomfort or dysfunction, management/treatment costs may be relatively high and life expectancy can be reduced.

Hitti-Malin RJ, Burmeister LM, Lingaas F, et al. (2021) A Missense Variant in the Bardet-Biedl Syndrome 2 Gene (BBS2) Leads to a Novel Syndromic Retinal Degeneration in the Shetland Sheepdog. Genes. 12(11): 1771. DOI: 10.3390/genes12111771.

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