This tree summarizes six Big Y tests for I-L233 "Western". The Big Ys sequenced around 10 million base pairs on each person's Y chromosome, and the six men had differences at two SNPs called A4223 and A417. The German-ancestry man at top was ancestral for both SNPs (Y4223- and A417-), the two Irish-ancestry men in the middle were derived for both (Y4223+ and A417+), and the three men at the bottom were Y4223+ and A417-.
Dozens of additional new SNPs were discovered in each man's Big Y results but at this point we have good evidence for only Y4223 and A417. When more Big Y tests are completed we will find a SNP specific to the branch at the top of the tree (for example), and we will find more branches not shown on this tree.
A417 is available for purchase at FTDNA and another company called YSeq.net for $39, and six people not shown on the tree have tested A417 as an individual test. Five were A417- and one was A417+. So in summary, twelve L233+ men have tested A417, and nine were A417- and three were A417+.
The five people who received A417- results from these individual tests could be Y4223+ or Y4223-. The one person who received A417+ results from his individual test is sure to be Y4223+ based on the tree above.
Unfortunately Y4223 is not available at FTDNA or YSeq.net for individual testing, but we have requested that FTDNA add it to their catalog.
From this testing so far, around 25% of L233+ men belong to the A417+ group. We can compare the 67 markers of the three A417+. and they are not very similar to each other. So the three A417+ men are not closely related, and the A417 mutation happened well over 1,000 years ago. I think we will find man more A417+ men, and I recommend the A417 test to all I-L233 "Western" men. Please feel free to email email@example.com with any questions.