Ralph The FTDNA TiP does indeed allow for RecLoh's and null markers. We have a very unusual result in the Aldous DNA project with both a RecLoh and a null marker: http://www.familytreedna.com/public/Aldous/default.aspx?section=yresults They do not show up in each other's match pages but when I use the TiP I get the following result: In comparing Y-DNA37 markers, which show 7 mismatches, the probability that (N2041) ... Aldous and (147566) .... Aldous shared a common ancestor within the last... ...4 generations is 0.05%. ...8 generations is 2.12%. ...12 generations is 12.52%. ...16 generations is 32.58%. ...20 generations is 55.47%. ...24 generations is 74.32%. The two men share a paper trail ancestor in the mid 1400s. Debbie Kennett