OMIA 001518-9615 : Progressive retinal atrophy, X-linked, type 2 in Canis lupus familiaris

Possibly relevant human trait(s) and/or gene(s) (MIM number): 300029

Mendelian trait/disorder: yes

Mode of inheritance: X-linked

Considered a defect: yes

Key variant known: yes

Year key variant first reported: 2002

Cross-species summary: This disorder has been renamed in OMIA on the basis of the review by Miyadera et al. (2012)

Species-specific symbol: XLPRA2

Species-specific description: The difference between XLPRA1 (OMIA 000831-9615) and XLPRA2 (this entry) is summarised by Appelbaum et al. (2020) as "XLPRA1-affected dogs have normal PR morphogenesis, after which progressive rod–cone degeneration develops in the peripheral retina, gradually advancing toward the optic disc. . . . The phenotype associated with XLPRA2 is very severe and manifests during early retinal development."

Molecular basis: Based on a comparative positional cloning approach (the canine disorder maps to a location on the canine X chromosome that is homologous with the location of the same disorder (RP3) in humans, which is due to mutations in the RPGR gene), Zhang et al. (2002) identified a "a two-nucleotide deletion (delGA) in 1084–1085" in the canine RPGR gene as a causal mutation for a form of X-linked PRA they call XPRA2. The authors noted that this deletion "results in a frameshift that significantly changes the deduced peptide sequence, causing an increased isoelectric point (4.30 versus 4.01), and leads to the inclusion of 34 additional basic residues before prematurely terminating translation 71 amino acids downstream".

Clinical features: Beltran et al. (2006): "Abnormal development of photoreceptors was recognizable as early as 3.9 weeks of age. Outer segment (OS) misalignment was followed by their disorganization and fragmentation. Reduction in length and broadening of rod and cone inner segments (IS) was next observed, followed by the focal loss of rod and cone IS at later time points. The proportion of dying photoreceptors peaked at approximately 6 to 7 weeks of age and was significantly reduced after 12 weeks. In addition to rod and cone opsin mislocalization, there was early rod neurite sprouting, retraction of rod bipolar cell dendrites, and increased Müller cell reactivity. Later in the course of the disease, changes were also noted in horizontal cells and amacrine cells." As summarised by these authors: "XLPRA2 is an early-onset model of XLRP that is morphologically characterized by abnormal photoreceptor maturation followed by progressive rod-cone degeneration and early inner retina remodeling. "

Breed: Mongrel.

Associated gene:

Symbol Description Species Chr Location OMIA gene details page Other Links
RPGR retinitis pigmentosa GTPase regulator Canis lupus familiaris X NC_051843.1 (33156658..33082215) RPGR Homologene, Ensembl, NCBI gene


By default, variants are sorted chronologically by year of publication, to provide a historical perspective. Readers can re-sort on any column by clicking on the column header. Click it again to sort in a descending order. To create a multiple-field sort, hold down Shift while clicking on the second, third etc relevant column headers.

WARNING! Inclusion of a variant in this table does not automatically mean that it should be used for DNA testing. Anyone contemplating the use of any of these variants for DNA testing should examine critically the relevant evidence (especially in breeds other than the breed in which the variant was first described). If it is decided to proceed, the location and orientation of the variant sequence should be checked very carefully.

Breed(s) Variant Phenotype Gene Allele Type of Variant Reference Sequence Chr. g. or m. c. or n. p. Verbal Description EVA ID Year Published PubMed ID(s) Acknowledgements
Mongrel Progressive retinal atrophy, X-linked, type 2 RPGR deletion, small (<=20) c.1084-1085delGA "a two-nucleotide deletion (delGA) in 1084-1085" in the canine RPGR gene 2002 11978759


Note: the references are listed in reverse chronological order (from the most recent year to the earliest year), and alphabetically by first author within a year.
2020 Appelbaum, T., Santana, E., Aguirre, G.D. :
Critical Decrease in the Level of Axon Guidance Receptor ROBO1 in Rod Synaptic Terminals Is Followed by Axon Retraction. Invest Ophthalmol Vis Sci 61:11, 2020. Pubmed reference: 32176262. DOI: 10.1167/iovs.61.3.11.
Dufour, V.L.L., Cideciyan, A.V., Ye, G.J., Song, C., Timmers, A., Habecker, P., Pan, W., Weinstein, N., Swider, M., Durham, A., Ying, G.S., Robinson, P., Jacobson, S., Knop, D.R., Chulay, J.D., Shearman, M.S., Aguirre, G., Beltran, W. :
Toxicity and Efficacy Evaluation of an AAV Vector Expressing Codon-Optimized RPGR Delivered by Subretinal Injection in a Canine Model of X-linked Retinitis Pigmentosa. Hum Gene Ther :, 2020. Pubmed reference: 31910043. DOI: 10.1089/hum.2019.297.
Switonski, M. :
Impact of gene therapy for canine monogenic diseases on the progress of preclinical studies. J Appl Genet :, 2020. Pubmed reference: 32189222. DOI: 10.1007/s13353-020-00554-8.
2017 Sudharsan, R., Beiting, D.P., Aguirre, G.D., Beltran, W.A. :
Involvement of Innate Immune System in Late Stages of Inherited Photoreceptor Degeneration. Sci Rep 7:17897, 2017. Pubmed reference: 29263354. DOI: 10.1038/s41598-017-18236-7.
2014 Genini, S., Guziewicz, K.E., Beltran, W.A., Aguirre, G.D. :
Altered miRNA expression in canine retinas during normal development and in models of retinal degeneration. BMC Genomics 15:172, 2014. Pubmed reference: 24581223. DOI: 10.1186/1471-2164-15-172.
2013 Genini, S., Beltran, W.A., Aguirre, G.D. :
Up-regulation of tumor necrosis factor superfamily genes in early phases of photoreceptor degeneration. PLoS One 8:e85408, 2013. Pubmed reference: 24367709. DOI: 10.1371/journal.pone.0085408.
2012 Beltran, W.A., Cideciyan, A.V., Lewin, A.S., Iwabe, S., Khanna, H., Sumaroka, A., Chiodo, V.A., Fajardo, D.S., Román, A.J., Deng, W.T., Swider, M., Alemán, T.S., Boye, S.L., Genini, S., Swaroop, A., Hauswirth, W.W., Jacobson, S.G., Aguirre, G.D. :
Gene therapy rescues photoreceptor blindness in dogs and paves the way for treating human X-linked retinitis pigmentosa. Proc Natl Acad Sci U S A 109:2132-7, 2012. Pubmed reference: 22308428. DOI: 10.1073/pnas.1118847109.
Miyadera, K., Acland, G.M., Aguirre, G.D. :
Genetic and phenotypic variations of inherited retinal diseases in dogs: the power of within- and across-breed studies. Mamm Genome 23:40-61, 2012. Pubmed reference: 22065099. DOI: 10.1007/s00335-011-9361-3.
2010 Genini, S., Zangerl, B., Slavik, J., Acland, GM., Beltran, WA., Aguirre, GD. :
Transcriptional Profile Analysis of RPGRORF15 Frameshift Mutation Identifies Novel Genes Associated with Retinal Degeneration. Invest Ophthalmol Vis Sci 51:6038-50, 2010. Pubmed reference: 20574030. DOI: 10.1167/iovs.10-5443.
2007 Zangerl, B., Johnson, J.L., Acland, G.M., Aguirre, G.D. :
Independent origin and restricted distribution of RPGR deletions causing XLPRA. J Hered 98:526-30, 2007. Pubmed reference: 17646274. DOI: 10.1093/jhered/esm060.
2006 Beltran, WA., Hammond, P., Acland, GM., Aguirre, GD. :
A frameshift mutation in RPGR exon ORF15 causes photoreceptor degeneration and inner retina remodeling in a model of X-linked retinitis pigmentosa. Invest Ophthalmol Vis Sci 47:1669-81, 2006. Pubmed reference: 16565408. DOI: 10.1167/iovs.05-0845.
2002 Zhang, Q., Acland, GM., Wu, WX., Johnson, JL., Pearce-Kelling, S., Tulloch, B., Vervoort, R., Wright, AF., Aguirre, GD. :
Different RPGR exon ORF15 mutations in Canids provide insights into photoreceptor cell degeneration. Hum Mol Genet 11:993-1003, 2002. Pubmed reference: 11978759.

Edit History

  • Created by Frank Nicholas on 02 Nov 2010
  • Changed by Frank Nicholas on 02 Dec 2011
  • Changed by Frank Nicholas on 12 Dec 2011
  • Changed by Frank Nicholas on 21 Sep 2012
  • Changed by Frank Nicholas on 18 Mar 2020