Generally, 85 percent of the tests come back as the sporadic, or naturally occurring form, 14 percent come back as the familial form that is passed down through generations and less than 1 percent come back as the variant form. There's never been a variant case acquired in the United States.  -   Tom Shanahan     Quotes
Generally, 85 percent of the tests come back as the sporadic, or naturally occurring form, 14 percent come back as the familial form that is passed down through generations and less than 1 percent come back as the variant form. There's never been a variant case acquired in the United States. Tom Shanahan