Progressive retinal atrophy / PAP-PRA1 (CNGB1-related) - Papillon / Phalène

What does this test examine?

This genetic test analyses the CNGB1 c.2387_2389delinsCTAGCTAC variant in the Papillon and Phalène. The disorder is described as progressive retinal atrophy, PRA, inherited retinal degeneration and PAP-PRA1, PRA-CNGB1 and Papillon/Phalène-type progressive retinal atrophy.

Progressive retinal atrophy is an inherited eye disorder in which photoreceptor cells in the retina gradually degenerate. Owners often first notice reduced vision in dim light or darkness, followed by progressive loss of daytime vision. The tested delins causes a frameshift and early stop codon in CNGB1, a channel protein important for photoreceptor function.

What does this disorder mean?

PAP-PRA1 mainly affects rod function, so reduced vision in dim light or darkness is often noticed first. The disease usually progresses slowly; dogs may retain useful vision for a long time, but progressive retinal changes and eventual vision loss can occur.

Practical value of this test

This DNA test is valuable because carriers usually look healthy and the first eye signs may appear only later in life. Testing before breeding allows breeders to distinguish clear dogs, carriers and genetically affected dogs, and to plan matings that do not produce affected puppies.

• Breeding selection: avoid unintended carrier-to-carrier matings while keeping useful lines available.
• Transparency: provide puppy buyers and other breeders with clear information about the tested PRA variant.
• Health planning: identify dogs with two copies early, so eye checks and follow-up can be planned more deliberately.

This variant explains a large proportion, but not all PRA cases in Papillon and Phalène dogs. The test is therefore highly useful for targeted breeding selection while breeders remain alert to other possible PRA causes.