The Japanese researchers first evaluated the dogs' pedigree to determine how the condition was inherited and found it was an autosomal recessive disease; in other words, a dog needs two copies of the mutated gene in order to be affected. This process also allowed the scientists to see which of the dogs was a carrier for the disease. The gene responsible for these dogs' condition remains a mystery, but the researchers believe a genome-wide approach by means of whole-genome sequencing will narrow their hunt.