Progressive retinal atrophy / JPH2-PRA (JPH2-related) - Shih Tzu

What does this test examine?

This genetic test analyses the JPH2 c.452T>G variant in the Shih Tzu. The disorder is described as progressive retinal atrophy, PRA, inherited retinal degeneration and JPH2-PRA, IRD-JPH2 and Shih-Tzu 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 nonsense variant creates an early stop codon in JPH2, a gene involved in calcium regulation and cellular architecture in neural tissues.

What does this disorder mean?

This form is mainly described as a later-onset retinal degeneration. Affected dogs may develop visual signs at about 5 to 9 years of age, with tapetal hyperreflectivity, pigment changes, optic nerve atrophy and progressive loss of vision.

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.

For Shih Tzu breeders, the test makes it possible to manage an inherited eye disorder genetically before dogs are used for breeding, even though clinical signs may appear later.