Why we separate clinical traits and health conditions
A clinical trait is a trait that your veterinarian can use to interpret your dog's unique clinical picture; however, it may not affect the way your dog looks or require monitoring and treatment. These are different from normal traits, like coat color or health conditions, which are associated with disease risk.
For example, Alanine Aminotransferase assesses a mutation in the GPT gene that is associated with low, but still within normal range, alanine aminotransferase (ALT) activity. ALT is an enzyme highly expressed in liver cells; it is used by most veterinarians as a measure of liver health. When the liver is inflamed or damaged, ALT activity increases dramatically. Healthy dogs with two copies of this mutation tend to have ALT activity that resides on the low end of normal—nothing to worry about, though. However, in the event of liver damage, these dogs' ALT activity may not increase outside the normal range of ALT activity.
What does this mean for you as your dog's owner? Not too much, unless you happen to be your dog's vet, as well! But as a veterinarian, this is a valuable piece of information that can be used to accurately assess your dog's health.