Progressive retinal atrophy / crd4-PRA / cord1 + MAP9 (RPGRIP1/MAP9-related) - Dachshund / English Springer Spaniel

What does this panel test examine?

This genetic panel combines two subanalyses for progressive retinal atrophy / crd4-PRA / cord1 in Dachshunds, Miniature Dachshunds and English Springer Spaniels. It assesses the RPGRIP1 c.142_143ins variant and the MAP9 c.75+181_1378-215del modifier.

crd4-PRA, formerly often called cord1-PRA, is an inherited retinal degeneration involving cone and rod photoreceptors. This means both daylight vision and low-light vision can deteriorate.

Why two variants?

This form has a more complex genetic background than many classic single-variant recessive tests. The RPGRIP1 variant is the main tested variant, but dogs with this variant alone can differ widely in age of onset and severity. The MAP9 deletion acts as a modifier: it does not cause PRA on its own, but can accelerate onset and progression when present together with the RPGRIP1 variant.

What does crd4-PRA mean?

Affected dogs can gradually lose vision, have difficulty tracking moving objects, become clumsy and develop night blindness or day-vision problems. With combined RPGRIP1 and MAP9 risk, signs can appear very early, while other dogs develop clear problems later in life.

Practical value of this test

For breeders, this panel is more informative than a single variant test when the goal is a fuller crd4-PRA risk assessment. The combined result helps distinguish carriers, dogs with two RPGRIP1 copies and dogs with additional MAP9 modifier load.

• Breeding plans: avoid combinations that can produce puppies at high risk of early retinal degeneration.
• Risk assessment: evaluate not only RPGRIP1 status, but also the modifier that can affect severity and onset.
• Targeted follow-up: use the result to plan eye monitoring and selection decisions more effectively.