A group of international researchers has recently identified a genetic mutation associated with progressive retinal atrophy, or PRA, a disease that can cause blindness in Labrador retrievers.

Three littermates with PRA were brought to the attention of the researchers by a foundation that breeds service dogs for visually impaired individuals. The researchers identified a genetic mutation in the three affected dogs that wasn’t found in the general U.S. population of Labrador retrievers. They also found 19 Labrador retrievers from the same kennel that carried the gene but were clinically unaffected.

Now that a gene has been identified, the goal is to develop a diagnostic test to help prevent genetic carriers from being used in breeding.