Genome-wide statistical evidence elucidates candidate factors of life expectancy in dogs.

It is well-established that large and heavy dogs tend to live shorter lives. In this study, we aimed to determine whether traits other than body size are associated with the life expectancy of dogs. We compiled a dataset of 20 phenotypes, including body size, lifespan, snout ratio, and shedding, into a single matrix for 149 dog breeds using data from the American Kennel Club and other peer-reviewed sources. The analysis revealed that drooling might be associated with both the lifespan and body mass index of dogs. Furthermore, a genome-wide association study with adjusted phenotypes and statistical verification methods, such as Mendelian randomization. Additionally, conducting differential gene expression analysis with the salivary gland for the 2 cases, hypersalivation/less drooling vs various body sizes, we could observe the hypersalivation-related proteins. This genetic analysis suggests that body size and drooling might be candidate factors influencing lifespan. Consequently, we identified several candidate genes, including IGSF1, PACSIN2, PIK3R1, and MCCC2, as potential genetic factors influencing longevity-related phenotypes.