Progressive retinal atrophy / MERTK-PRA (MERTK-related) - Swedish Vallhund

What does this test examine?

This genetic test analyses the MERTK LINE-1 insertion variant in the Swedish Vallhund. The disorder is described as progressive retinal atrophy, PRA, inherited retinal degeneration and MERTK-PRA, IRD-MERTK, retinopathy and Swedish-Vallhund 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 intronic LINE-1 insertion affects regulation of MERTK and is strongly linked to this inherited retinopathy.

What does this disorder mean?

This form can vary strongly in age of onset and severity. Eye abnormalities may be detected early, while clear vision loss often appears later. Reported signs include red-brown tapetal discoloration, retinal thinning, night blindness, loss of daytime vision in later stages and eventual blindness in some dogs.

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.

The test helps in a breed where clinical severity and age of onset vary widely, so breeders do not have to wait for eye abnormalities before planning genetic combinations.