Disease overview

Photoreceptor dysplasia is a form of early-onset, progressive retinal atrophy (PRA). This is a non-painful eye disorder that affects both types of photoreceptors: rods and cones. Rod cells are responsible for vision in low light conditions and for detecting and following movement, while cone cells detect color and adjust brightness, but do not work as well in low light. This disease can lead to complete blindness.

Gene name

PPT1

Inheritance

Autosomal recessive

Signs and symptoms

Photoreceptor dysplasia is a form of PRA typically characterized by a loss of vision over time, which can allow for a dog to adapt more easily. Changes in behavior, such as reluctance to go down the stairs or into a dark room, and/or bumping into door frames and furniture, may be signs that a dog is experiencing vision loss. There may be an increased reflectivity to the eye. These changes first cause night blindness, progressing to vision loss during the day and then often to complete blindness for most dogs. Affected dogs have been noted to have normal eye anatomy at 10 months old, but then develop advanced retinal disease by 3 years of age.

How is it diagnosed

Thorough examination of the eyes and clinical signs. A veterinary ophthalmologic exam can determine if there are changes in the eye that have or will lead to vision loss. Genetic testing is necessary to determine if there is an underlying genetic cause, which can assist veterinarians with diagnosis and help breeders identify affected and carrier dogs.

Breeds at higher risk

Citations

Murgiano L, Becker D, Torjman D, Niggel JK, Milano A, Cullen C, Feng R, Wang F, Jagannathan V, Pearce-Kelling S, Katz ML, Leeb T, Aguirre GD. Complex Structural PPT1 Variant Associated with Non-syndromic Canine Retinal Degeneration. G3 (Bethesda). 2019 Feb 7;9(2):425-437. doi: 10.1534/g3.118.200859. PMID: 30541930; PMCID: PMC6385984.

Zhang Q, Baldwin VJ, Acland GM, Parshall CJ, Haskel J, Aguirre GD, Ray K. Photoreceptor dysplasia (pd) in miniature schnauzer dogs: evaluation of candidate genes by molecular genetic analysis. J Hered. 1999 Jan-Feb;90(1):57-61. doi: 10.1093/jhered/90.1.57. PMID: 9987905.

Kaukonen M, Quintero IB, Mukarram AK, Hytönen MK, Holopainen S, Wickström K, Kyöstilä K, Arumilli M, Jalomäki S, Daub CO, Kere J, Lohi H; DoGA Consortium. A putative silencer variant in a spontaneous canine model of retinitis pigmentosa. PLoS Genet. 2020 Mar 9;16(3):e1008659. doi: 10.1371/journal.pgen.1008659. PMID: 32150541; PMCID: PMC7082071.

Disclaimer

Disease diagnosis and treatment should always be performed by a veterinarian. The following information is for educational purposes only.