A Set of Distinctive Marker Values Defines a Y-STR Signature for Gaelic Dalcassian
Dennis M. Wright
Analysis of 25-marker short tandem repeat haplotypes in
the Ysearch database reveals a distinctive Y-DNA signature that peaks in frequency in the Irish counties
of Tipperary, Clare and Limerick. These counties
were the hereditary homelands of the Dál gCais families, also called Dalcassian,
septs descended from Cas, born CE 347, sixth in
descent from Cormac Cas,
King of Munster. Dalcassian surnames are more
strongly represented with this signature than other surnames. A Y-STR signature for the northern Uí
Néill lineages was previously identified. In the present paper, we present evidence for
the signature of the Dál gCais, presently referred to as “Irish Type III.”
Address for correspondence: Dennis Wright, [email protected]
10, 2008; accepted: January 4, 2009.
With the established patrilineal transmission of Y-DNA
with surnames in Ireland,
researchers have for some time sought to find sets of short tandem repeat (STR)
marker values that might identify the great ancient families of Ireland. The distinctive STR
signature of one Haplogroup R1b cluster was identified as “North West Irish”
(Wilson, D 2004) and separately and formally (Moore et al 2006) as the “Irish
Modal Haplotype” (IMH). Wilson also showed the connection of IMH
with the Uí Néill,
kings of medieval Ireland,
and specifically descendants of the semi-legendary fifth-century king, Niall of
the Nine Hostages. It was later found that this cluster is derived for the
single nucleotide polymorphism (SNP), M222, (McEwan, 2006) and was first
recognised as the Haplogroup R1b1c7 in the R1b-Tree at ISOGG (2007). The recent identification of other R1b SNPs
has resulted in the R1b1c7 (R-M222) Haplogroup having a different nomenclature
in each subsequent ISOGG R1b Tree.
Another major dynasty of Ireland was the
descendant families of Cas,
a semi-legendary king who was born in CE 347.
They were known as the Dál gCais or Dalcassian
et al (2008) studied 17-marker R1b STR
haplotypes looking for patterns of kinship in Munster and
concluded there were no significant signatures for the Dál
gCais or Eóganacht
septs. This might well be expected if
the study only looked at markers where the Dalcassian
had no distinctive values.
Proper association of signatures with particular clans
or septs requires more markers to be analysed than have been commonly used in
early, and even very recent, Y-chromosome population studies. Public databases like Ysearch,
Ybase, Sorenson Molecular Genealogy Foundation
(SMGF), and Ancestry.com constitute rich hunting grounds for researchers that
were not previously available, providing abundant haplotypes of 25, 37, 43, and
A Dalcassian signature is
evident when specific STR
markers are included in the studied R1b haplotype. Present day possessors of this signature, as
found in public databases, trace their ancestors primarily to the Counties of
and Limerick and many
carry surnames of the Dalcassian families.
In their paper Wilson JF et al (2001) identified a
six-marker haplotype that they called the Atlantic Modal Haplotype (AMH). They found the AMH
to be representative of approximately 90% of the R1b in Ireland. With the collection of thousands of R1b
haplotypes in genetic genealogy databases, it has been possible to identify the
modal values on many more markers for the AMH
haplotype. For example, the modal values
on the first 25 markers commonly offered by several testing laboratories have been
determined and are posted on Ysearch within the ID C7BED
and shown in Table 1.
Atlantic Modal Haplotype.
The markers in bold were not
in McEvoy (2008)
In April 2006 Kenneth Nordtvedt noted (Nordtvedt,
2006) that a variety of Irish R1b existed that matched the AMH
except for the unusual features,
This Irish haplotype differed from the AMH
modal values shown in Table 1 on these seven markers. A summary of Nordtvedt’s
original suggestions and subsequent developments by others has been provided by
Building on Nordtvedt’s
findings, a search for R1b haplotypes was undertaken in two public databases, Ysearch and Sorenson Molecular Genealogy Foundation (SMGF).
A third public database, www.ancestry.com, was
considered for searching, however, as the origin of the earliest known ancestor
is not recorded, this database was not useful in the current study.
Since a minimum of eight markers are need for searches
in these databases, the values Nordtvedt had identified were used, together
as this marker has been found to generally have the value of 12 for R1b. The search criteria are shown in Table 2:
Search Criteria Used for this Study
A group of 105 haplotypes were found that fully
matched all seven distinctive marker values, and 191 haplotypes in total were
found to belong to the cluster, defined as being within a genetic distance of
two (GD=2) on these seven markers and up to GD=5 from the AMH
on the balance of the 25 markers.
Records that occurred in more than one database were only counted
once. The process of selecting the 191
haplotypes, and the haplotypes themselves, is shown in the Supplemental Data
allows the results of 96 Y-STR
markers to be recorded and many of the haplotypes identified by the search
criteria for DYS459,
DYS464 and DYS439,
have tested to 37, 67 and up to the maximum of 96 markers. When the modal values were
calculated for each marker tested for the 191 haplotypes in the study and
compared to the AMH modal values, several additional markers were found
to be distinctive for this cluster. These are shown in Table 3.
Markers that Distinguish the Irish Type III Cluster
This cluster is being called “Irish Type III”
by genetic genealogy researchers as two other clusters have previously been
identified, the NWIrish or Uí
Néill, Ysearch ID M5UKQ
and South Irish, Ysearch ID XREMB.
A Ysearch record for the modal values of Irish Type III,
with ID NT4BZ, has been established to facilitate meaningful searches for
Geographical Origins of the Cluster
Analysis showed 54% of our sample knew the country of
origin of their ancestor in Europe,
and 75% of these gave their origin as Ireland, 13% Scotland and 11% England. See Table 4 and Figure
1. Many of those who only
knew of colonial origins for their earliest known ancestor, have Irish names,
giving further confirmation of the Irish origin of the members of this cluster.
Origins of known ancestors in Europe
of Origin for Ancestors of
of Irish Type III Cluster
Of those who gave their origin as Ireland and where their
county of origin was known, 26% identified Co. Clare, 23% Co.
and 16% Co. Limerick, a total of 65%, as shown in Table 5 and Figures
2 and 3. These Northern Counties of Munster have
historically been known as “Thomond.” The principal clan of Thomond
was the Dál gCais
of which O’Brien is the principal family.
Counties Where Ancestral Lines
are Known to
Figure 2. Origins of known
ancestors in Ireland
Figure 3. Location of the earliest
known ancestors is concentrated in Munster
take their name from Brian Boru, High King of
Ireland, CE 926-1014, and the family were Kings, Princes and Earls of Thomond until the 18th century.
Origin of the Dalcassian
and Related Surnames
The history and pedigree of
the Dál gCais
and their descent from Cas,
born CE 347, sixth in descent from Cormac Cas, son of Oilioll Olum, King of Munster, is detailed in Irish Pedigrees or
the Origin and Stem of the Irish Nation, (O’Hart,
further states that in following generations, as surnames were adopted, many
families are patrinomically linked to this line and
he identifies the following families as Dalcassian:
MacArthur, O'Beollan (or "Boland"), O'Brien, O’Brennan,
O'Casey, MacConsidine, O'Cormacan, Cosgrave, MacCraith, (or MacGrath),
O'Curry, Eustace, Glinn,
Glynn, Hearne, O'Hogan, O'Hurley,
Magan, Maglin, MacMahon,
O'Meara, Muldowney (now "Downey"), O'Noonan, Power, Quirk, O'Regan, Scanlan, O'Seasnain,
Figure 4 shows the connections of the Dalcassian
families listed above to the O’Brien line.
If the pedigrees are correct, then the same Y-STR signature should be evident in each of these families.
Figure 4. Families descended from Cormac
Cas, hence Dalcassian surnames in the Irish Type III
The surnames that occur more
than once in our sample of 191 haplotypes are shown in Table 6.
Surnames Found in the Irish Type III
(1985) says of some of the families that are not included in Figure 4:
and Bryant are variations of O’Brien, descended from Brian Boru.
The name of six unrelated septs. It is
chiefly found now in the south-west of Munster. One sept was Dalcassian and was
seated at Liscannon near Bluff in Co. Limerick.
hereditary poets to the O’Briens.
MacEnchroe, all Crowes in
their homeland, Thomond, are of native Irish stock,
from Clare and Tipperary.
descended from Ógan, an uncle of Brian Boru.
is from Derry, but O’Hartigan is from the same Christian name, ‘Art’. This sept is Dalcassian, located in East Clare and North
Thomond Kennedys are
descended from Cinnéad, a nephew of Brian Boru.
hereditary marshals to the O’Briens.
The more frequently occurring surnames in Table 6
are either Dalcassian, as defined by O’Hart (1892), or have a strong connection with Thomond, such as Butler.
(Morgan) O'Brien of Ballyphillip, Co. Limerick
married Eleanor Butler, daughter of Capt Edward Butler of Bansha, descendant of Thomas Butler, 10th Earl of Ormonde. As was
often the case, Morgan O'Brien took Butler as his surname, probably
as part of his and his wife’s succession to the lands of Bansha,
This may be the link whereby many of the name Butler have Irish Type III haplotypes,
was considered non-Dalcassian in the present study.
Surname Representation in Irish Type III
29% of the 191 haplotypes in the present study
belonged to Dalcassian surnames. The Ysearch
database was searched to see what proportion of each surname found in the study
cluster was Irish Type III. Only those records that recorded DYS459
were analysed. For each surname in Figure
4, the percentage in Ysearch that were Irish Type
calculated and the results are shown in Table 7. Similarly, Ysearch
was searched for the non-Dalcassian surnames that
were found in our study sample, and the percentatge in
Ysearch that were Dalcassian
was recorded for each of these surnames as shown in Table 8. Non-Dalcassian
surnames with less than three occurrences in our study sample were not
considered in this analysis.
Some surnames, including
O’Brien and Casey, occur in more than one county (MacLysaght,
1985), so septs with origins outside Thomond may well
have different Y-STR signatures from the Dál
It was also common for followers
of Medieval leaders to take their clan leader’s name
to show their allegiance and so the Y-STR signature of their descendants may well not match that of their
leader. These acts of allegiance
occurred both before and after the use of surnames were adopted. For these
reasons, many with Dalcassian surnames do not have
the Irish Type III Y-DNA signature.
Surnames with the greatest
representation in the cluster and with the highest percentage of the Irish
Type III signature are the traditional Dalcassian
surnames of O’Brien/Bryant, O’Casey, McCraw/ McGraw/McGrath and O’Hogan.
These four surnames are shown in bold in Table 7.
Many allegedly Dalcassian families are not present in this cluster, but
many such families have no members with records in Ysearch.
Non-Dalcassian Surnames Irish Type III
There are many non-Dalcassian surnames found in small numbers in the study
sample. Some may have resulted from
ancient tribal allegiances and marriages where the male takes the female’s
family name, as in the case of Butler and probably also MacNamara. Adoptions and out-of-wedlock situations will
undoubtedly have also contributed to this situation. When considered as a percentage of the total
entries of that name in Ysearch, other than those
that have a connection with the Dál gCais as detailed above, non-Dalcassian
surnames are invariably a minor contribution.
See Table 8.
Members of the Y-STR haplotype cluster, Uí Néill,
are found to be derived for the SNP, M222.
No SNP has yet been discovered that uniquely defines the Irish Type III cluster. SNP testing of members
of this cluster has shown the cluster to be derived for the SNPs, S116/P312 and
L21/S145, with all SNPs below L21/S145 being found ancestral. These results are shown on the Irish Type III website – SNP markers. This
cluster exists within the R1b1b2a1a2f* (R-L21*) sub-clade (ISOGG, 2009).
An R1b cluster with a
distinctive Y-STR modal haplotype has been identified, which is
commonly referred to as “Irish Type III” by
genetic genealogy researchers. It is shown in Ysearch
as ID NT4BZ.
This modal haplotype is
shown to have its origins in the counties of Clare, Limerick and Tipperary, the hereditary lands of the Dál
gCais and their principal family, the
O’Brien. The Y-STR signature of the cluster is found in many descendants of the Dál gCais sept including, O’Brien and its variations Bryan and
Bryant, Casey, Hogan, Kennedy, and McGrath.
A set of distinctive marker
values has been shown to exist that defines the Y-DNA STR Signature for Gaelic Dalcassian
The haplotypes used in this
study are available in a supplementary data file at:
Thanks are extended to Dr.
Kenneth Nordtvedt who identified the initial markers for this R1b cluster in
April 2006 and pointed to its concentration in Ireland.
The availability of the Ysearch and SMGF databases were invaluable in enabling this
cluster to be studied.
Irish Type III website – SNP markers
ISOGG 2007 Y phylogenetic
tree, R sub-page
ISOGG 2009 Y phylogenetic
tree, R sub-page
Sorenson Molecular Genealogy
Ysearch database (2008)
Blackall H (2008) The Butlers of County Clare. Clare
County Library web site:
http://www.clarelibrary.ie/eolas/coclare/genealogy/butlers/notes.htm See note 127 on the Butler-O’Brien
Desmond T (2008) South Irish R1b Y-DNA. Website:
Type III website – SNP markers. See Web
ISOGG--International Society of Genetic Genealogy (2007) Y phylogenetic tree, R sub-page (2007
Archive). See Web Resources.
ISOGG--International Society of Genetic Genealogy (2009) Y phylogenetic tree, R sub-page. See Web Resources.
B, Simms K, Bradley DG (2008)
Genetic investigation of the patrilineal kinship structure of
early Medieval Ireland. Am J Phys Anthropol,
McEwan J (2006) R1b1c7 Haplogroup
M222 SNP aka North West Irish Variety, IMH and R1bSTR19Irish. Website:
MacLysaght E (1985) Irish Families, Their Names,
Arms and Origins. Irish Academic
MacLysaght E (1991) The Surnames of Ireland. Irish Academic Press, Dublin.
LT, McEvoy B, Cape E, Simms K, Bradley DG (2006)
A Y-Chromosome Signature of Hegemony in Gaelic Ireland. Am J Hum Genet, 78:334–338.
Nordtvedt K (2006) E-mail to Rootsweb Genealogy-DNA List, 7 April 2006:
O’Hart J (1892) Irish Pedigrees; or the
Origin and Stem of the Irish Nation.
Reprinted by Genealogical Publishing Company, Baltimore, 1976. The pertainent excerpt may be found on-line at:
Wilson D (2004) Website http://www.m222.net/R1b1c7
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M, Thomas MG, Bradman N, Goldstein DB (2001) Genetic
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