Test Detail

CNGA1-PRA - Shetland Sheepdog

Ocular · Dog

Form of progressive retinal atrophy (PRA) of the Shetland Sheepdog associated with a mutation in the CNGA1 gene, which encodes a subunit of the cyclic nucleotide channel involved in phototransduction. It produces photoreceptor degeneration with progression to blindness. The disease is inherited recessively and the genetic test allows carrier screening.

Inheritance pattern	Autosomal recessive
Gene / Mutation	CNGA1 c.1752_1755delAACT p.(Thr585Serfs*9): 4-bp deletion in exon 9 that causes a frameshift and premature stop codon (g.43831897_43831900del, CanFam3.1; OMIA:001977-9615). Causal variant of PRA described in the Shetland Sheepdog (Wiik et al. 2015). Do not confuse with the BBS2 PRA of the same breed.
Penetrance	Penetrance expected to be complete in homozygotes; heterozygotes are asymptomatic carriers. Limited data on the exact age of onset.
Code	qyzy
Turnaround time	15 days
Price	52,60 €

Incidence

Specific to the Shetland Sheepdog. Carrier frequencies are not consolidated in the literature; limited data.

Breeder management

- Test breeding animals before mating
- Do not mate two carriers: 25 % of the litter would be affected
- A carrier can be mated with a clear animal; test the offspring intended for breeding
- Periodic ophthalmological examination to rule out other forms of PRA in the breed

Specialist notes

Differential diagnosis with other forms of PRA described in the Shetland Sheepdog and with acquired retinal degenerations. The electroretinogram is useful to confirm the retinal origin. A negative test for CNGA1 does not exclude other PRAs in the breed.

References

1. Wiik AC et al. 2015. Progressive retinal atrophy in Shetland sheepdog is associated with a mutation in the CNGA1 gene. Animal Genetics. PMID: 26202106
2. OMIA:001977-9615. Retinal atrophy, progressive, CNGA1-related. Online Mendelian Inheritance in Animals.

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