When you agree to genetic testing, you expect a yes or no answer:  yes, you have an abnormal change in a gene that increases your cancer risk, or no, you don’t. But sometimes, you might not get a clear “yes” or “no.” You might just get a “maybe.”

“That’s what you’ll hear if you have a variant of uncertain significance, or VUS for short,” says Sara Wofford, a genetic counselor at MD Anderson The Woodlands.

Unlike harmful...