The Clan Colla 425 null project is for anyone who has the R-Z3000 SNP or is predicted to have it based on the Y-67 test. "425 null" refers to STR 425=0, a predictor of Clan Colla DNA in the Y-67 test. (You do not need to know what SNPs and STRs are, but SNP stands for "single nucleotide polymorphism" and STR stands for "short tandem repeat.") R-Z3000 is the Y-DNA SNP of two groups: - R-Z3008 - SNP of The Three Collas, who lived in 4th century Ulster - R-Z16270, R-Z29586, and BY3160 - SNPs of cousins of The Three Collas The best test for Clan Colla DNA is Big Y-700. It will tell you where you fall on the Clan Colla Big Y SNP tree now and as it grows in the future. Y-67 can predict Z3000, but it does not tell you where you fall on the Z3000 SNP tree. See the Background page for: - Important information about joining the project - How we identified the Y-DNA of The Three Collas - Clan Colla Big Y SNP tree - Testing alternatives - Colla subgroups - FTDNA test results - Project administrators - Who were The Three Collas?