Progressive retinal atrophy / crd-PRA (NPHP4-related) - Dachshund

What does this test examine?

This genetic test analyses the NPHP4 c.479_526+130del variant in the Dachshund. The condition is known as progressive retinal atrophy / crd-PRA and is also referred to as CRD^SWHD, crd-PRA, crd, NPHP4-related cone-rod dystrophy and progressive retinal atrophy. The result shows whether the dog carries zero, one or two copies of the tested variant.

The NPHP4 gene is involved in normal photoreceptor function in the retina. The tested variant causes this form of inherited retinal degeneration and can lead to progressive loss of vision.

What does this condition mean?

In this Dachshund variant, retinal photoreceptors are progressively affected. Night vision and day vision can decline as retinal degeneration progresses.

In progressive retinal atrophy and cone-rod dystrophy, the light-sensitive cells of the retina gradually lose function. Dogs may develop difficulty seeing in dim or bright light, problems tracking moving objects, clumsiness and, over time, severe visual impairment or blindness.

Inheritance and result

The trait follows autosomal recessive inheritance. A clear dog does not carry the variant. A carrier has one copy and is usually not affected, but can pass the variant on. A dog with two copies has the affected genotype.

• N/N - no copy of the tested variant detected.
• N/var - carrier: one copy of the tested variant detected.
• var/var - affected genotype: two copies of the tested variant detected.

Practical value of this test

For breeders, this test is valuable because carriers can look completely normal. The result makes it possible to plan matings, manage carriers responsibly and greatly reduce the risk of puppies with inherited retinal degeneration.

The test is especially relevant for Dachshund varieties in which this deletion has been documented and helps breeders avoid recessive risk matings.