The Y-chromosome DNA (Y-DNA) marker DYS389 is a single STR marker that has four parts: m, n, p, and q.

At FamilyTreeDNA, we have two tests for DYS389. The first test looks at the first two parts of marker DYS389 (m and n). This is what we call DYS389I. The second test looks at all four parts of DYS389 (m, n, p, and q). This is what we call DYS389II. There are, by scientific convention, two ways to display the result of the second test. The first way to display the result is by showing the exact result from the original test. That is the total for the entire DYS389 marker (m+n+p+q). This is how FamilyTreeDNA displays the result.

The second way is to show the result only for the second section that is tested by subtracting the DYS389I score from the original second test score. This is how the Genographic Project 1.0 test displayed the result. Some older publications also use this method.

As long as you know which method is being used, you can convert between the two. For example, you add together the two DYS389 values from the Genographic Project to get the DYS389II value for FamilyTreeDNA. To convert to m+n, p+q format, subtract the DYS389I value from the DYS389II value in your FamilyTreeDNA results. This is the DYS389II value for the Genographic Project and elsewhere.