Gerry, Thanks for the statistics. I do have a Byrne cluster in Louth (see Lineage IV at www.worldfamilies.net/surnames/byrne/results) that number eight men tested. They are in two families but all are related. Two have tested L21 but nothing further. They are not M222 and I cannot figure out what they are. The nearest they seem to come to other surnames is 37/12. Oral and written histories connected them to the O'Byrne Clan of Leinster, allegedly a group sthat Feagh MacHugh O'Byrne sent north to aid the O'Neill, but DNA shows no connection. As for M222, and the Muintir Birn, I really must get up into Armagh where the records show numerous Byrne families, and I have no idea who or what they are. We have very few Ulster Byrne tested. One from Down is not close to any other project member, our one and only from Armagh is Airghialla-2, a man who traces to Co. Antrim turned out to be Sept O'Beirne of Roscommon, etc. Ain't it fun. Paul