Progressive retinal atrophy (PRA) in Labrador Retrievers

Progressive retinal atrophy comprises a large group of hereditary diseases that are the leading cause of blindness in various dog breeds. Individuals affected by PRA exhibit a similar sequence of clinical abnormalities throughout the course of the disease. Symptoms begin with night blindness, followed by gradual loss of daytime vision and eventual blindness in all light conditions. Routine eye examinations reveal a gradual loss of light-sensitive cells in the retina due to degeneration or atrophy of the retina, which gives the disease its name.

A mutation c.1607_1609del in the GTPBP2 gene has been discovered in Labrador Retrievers. The onset of clinical symptoms in this variant is between 7 and 18 months of age.

The mutation is inherited in an autosomal recessive manner. It only manifests itself in individuals who have inherited the mutated allele from both parents (recessive homozygotes). Heterozygotes are individuals who have inherited the mutated allele from only one parent, show no symptoms of the disease, and are clinically healthy. However, they can pass the mutated allele on to their offspring. If two heterozygous individuals mate, theoretically 25% of their offspring will be completely healthy, 50% will be carriers, and 25% will inherit the mutated allele from both parents and will therefore be affected by PRA.

Genetic testing can clearly reveal an animal's genotype and is a useful tool for breeders to prevent the unintentional breeding of affected puppies.

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References:

Murgiano, L., Niggel, J.K., Akyürek, E.E., Sacchetto, R., Aguirre, G.D. : GTPBP2 in-frame deletion in canine model with non-syndromic progressive retinal atrophy. Sci Rep 15:6079, 2025. Pubmed reference: 39971978. DOI: 10.1038/s41598-025-89446-7.