CTS4466 is the SNP that defines the Irish Type II subclade, which was identified by the respected physicist and nonpareil citizen scientist Dr. Ken Nordtvedt in 2006.  It was recognized by its distinctive haplotype prior to the discovery of any SNPs associated with it. In 2012, the Geno 2.0 test through National Geographic identified two SNPs – CTS4466 and CTS5714.  Then the 1000 Genome project added two more – CTS3974 and CTS8358.  They were present in everyone with the Irish Type II signature.  Since then, an ever increasing number of other SNPs have been discovered through the SNP tests mentioned at the bottom of the page offered by Family Tree, particularly the BIG Y test.

 
Objectives
 
The R1b-CTS4466 Plus project will research the parameters of this major subclade which features strongly in the south of Ireland, but it is found as well in other areas of the Isles, including some in the west of Ireland, Wales, western England, an apparent branch in Northern Ireland and Scotland and a few continentals.  We hope to discover the ancient history of this subclade - where it may have originated, how old it might be, which groups within it share more recent ancestry and how different branches may have developed and migrated from the time of the common ancestor.

 
Membership Criteria

To meet the objectives of the project, we seek to limit membership to those who have tested positive for at least one of the SNPs defining Irish Type II or have a haplotype consistent with that identified through research in the Family Tree DNA database.
 
Interested parties are invited to join, even if not SNP tested, with the understanding that the Project Administrators will review the participant’s haplotype and, at their discretion, determine if there is a likelihood of it proving positive for the defining SNPs. If accepted, we expect that the participants will be willing to test for further SNPs as suggested, based on the discoveries as we progress.

Those who are deemed not to meet these criteria will be asked to leave the project or accept that the Project Administrators will remove them from it.

The Irish Type II Modal & CTS4466 Ancestral Haplotype

A modal haplotype is a compilation of the most common values of a particular haplotype.  There are twelve markers that distinguish the Irish Type II modal.

DYS391 = 10
DYS385b = 15
DYS439 = 11
DYS447 = 24
DYS456 = 15
DYSCDYb = 37
DYS442 = 13
DYS565 = 11
DYS636 = 11
DYS532 = 14
DYS504 = 16
DYS635 = 24
DYS510 = 18

These marker values are compared to the modal of the ‘Super Western Atlantic Modal Haplotype’ as described in Appendix 1 of Nigel McCarthy’s PHYLOGENETIC ALIGNMENTS WITH GENEALOGIES OF DESCENT FROM AILILL ÓLOM (available at https://mccarthydna.wordpress.com/). 

In his paper, McCarthy suggests that the Ancestral Haplotype of CTS4466 at marker DYS439 may have been 12, the same as the SWAMH, prior to the early branching of A7751, which retained the 12, and S1115 where the 11 mutated and became predominant.

In any case, most present-day haplotypes will be different as a consequence of mutations (changes to the STR values, or 'alleles') which have occurred since the time of any Ancestral Haplotype. This often includes further changes at the STR markers highlighted above as significant in identifying the Ancestral Haplotype.

SNP Testing

FTDNA began exploring SNP testing through the 'Walk Through the Y' test in 2010.  They then offered individual SNP tests and later developed SNP Pack tests and their first iteration of the Big Y.  As more people tested, the Y haplotree expanded considerably and the individual and Pack tests became less useful.  They are no longer available.  The BIG Y test improved considerably and has become much more affordable than it was at its outset.  It is now the only choice for SNP testing.  If a new tester has the funds, the current version is the Big Y-700 and is by far the best choice to enter the world of Y-DNA testing.

In addition to 500k+ known SNPs on the Y chromosome, the Big Y-700 tests 700 STR markers including the Y-DNA111 which is offered separately at a lesser cost.  The additional STRs that are captured by the Big Y test don't display on the Results spreadsheet, but they are reported on the Big Y STR Results link.  Later STRs are generally less volatile than those in the Y111 sets and are useful when comparing more distant relationships.  Nigel uses them in developing his IT2 Phylogenetic Tree.  Family tree have more details about the test at their link:  https://www.familytreedna.com/learn/y-dna-testing/big-y/

The BIG Y test provides a dedicated Big Y Results page with details of Matches, Named Variants, Private Variants and a Block Tree, displaying neighboring branches and individuals in those branches listed on the Matching link.  It has a link to Export (CVS) that can be downloaded that contains all that data displayed.  In addition, the participants can Download Raw Data that has more information, and if they pay an additional fee, they can request a BAM file which has all the raw data for further analysis.  Unless the participant is comfortable with handling large files (they're really huge) we don't recommend they try to analyze them themselves.

R1b-CTS4466 Plus Haplogroup Forum

We have moved to a new forum at https://groups.io/g/R1b-CTS4466-Plus for those whose paternal ancestry places them in the CTS4466/Irish Type II haplogroup/subclade. There we can network with one another, pool our efforts, discuss research and share results. Members of the project are not required to join, but you are encouraged to participate if this sparks your interest.  Likewise, you need not be in the project to join the forum.  If you are confused by any of the science, terminology, FTDNA's website, or anything else relating to the project or genetic genealogy in general, please feel free to post your comments, questions, and concerns in the R1b-CTS4466 Plus group.  

R1b-CTS4466 Plus FAQs

We've prepared a brief document with some of the questions we receive from participants.  It is available in the files section of the Forum.


R1b-CTS4466 Plus Project Privacy Statement

As Administrator and Co-administrators of the R1b-CTS4466 Plus Project, in addition to abiding by the Privacy Policy that Family Tree posts, we wish to assure you that we give you, as a member of this Project, our priority in protecting your privacy and the confidentiality of your personal data.

What personal data about you do we hold or have access to?

The only personal data about you that we hold or have access to is data which has been made available to us by Family Tree DNA with your consent, to the access level you have chosen, and additional data which you may have given us directly by e-mail.

What use do we make of this personal data?

The only use we make of this data is that relevant to meeting the goals of our Project.  These goals require Project Administrators to be able to review the participant’s haplotype and, at their discretion, their personal data to determine and advise the project member on potential additional testing for the participant’s and the project’s benefit.

We would not publish or share your full name, e-mail address or other contact details with any other project member or other person or organization without your specific written approval, unless we were legally obliged to do so.

We will not publish or share your DNA test results except in anonymized form, limited to kit number and surname or ancestral surname.  The Results spreadsheet on our website also contains your Paternal Ancestor Name and Country of origin.

How long do we hold this personal data?

We hold this data for as long as you remain a member of our Project.  If you wish to withdraw from our Project you may do so by clicking the ‘Leave’ button on the Project Preferences link of your Account Information page.  Any posts on our R1b-CTS4466-Plus Forum can be deleted, but we cannot retrieve information that may have been previously posted in a public domain.  We would do our utmost to identify and delete any emails you have shared with us if you request us to do so.

In our administration of this Project, along with Family Tree’s commitment to you, we will comply with the requirements concerning the privacy of project members that are contained in the European Union’s General Data Protection Regulation which enters into force on 25 May 2018, regardless if you reside in the EU or elsewhere.

We endeavor to respond promptly to any queries, errors or complaints you may bring to our attention about our handling of your personal data associated with this Project.

We may update this Statement as circumstances arise.

The CTS4466 Tree

The haplotree listing all the SNPs associated with the CTS4466 haplogroup continues to expand as more people test the Big Y.  Each kit that has SNP tested can access where they belong on the Y-Haplotree through their Y-DNA 'Haplotree & SNPs' link and the Big Y 'Block Tree'.  However, neither of these sources displays the full tree without manipulating all the drop-down arrows and other maneuvers.  Our list of SNPs below contains the complete CTS4466 haplotree, and Joe regularly updates it.    

Latest Background Tree as of 25 July 2026:

Last updated 25 July 2026