The New Mexico Genealogical Society
DNA and Genealogy
Discovering Your Native American
Heritage Using Genetic Ancestry Testing
by Ripan S. Malhi, Ph.D and Amy J. Schilling, MS
Trace Genetics, a DNAPrint genomics company
From the New Mexico Genealogist, December 2005.
with permission from
Trace Genetics
Debra Ann Royer was adopted and grew up wondering about her biological family. People
always told her
she looked Native American, but Debra was never able to uncover any information
-- until now. Genetic
testing is the most universal and verifiable method for tracing biological ancestry.
Where the written record
stops or is unavailable, genetic testing can reveal or confirm biological ancestry.
Debra Ann used the Native
American mtDNA test that traces maternal lineage and discovered that her maternal
ancestors were Native
Americans that belonged to the Na-Dene language group, most likely either Navajo
or Apache.
“It is not easy emotionally to not know where you come from or what your heritage
is but now that I know at least part of my ancestry I am hoping the rest will fall
into place,” said Royer.
Stories such as Debra’s are not uncommon as the services of genetic testing
have become more accessible
to the general public. Most genealogists are familiar with the large number of ongoing
genetic surname
projects that are able to confirm familial lineages, but there are also many benefits
to genetic testing at the
level of the individual. In most cases, genetic tests strengthen/validate existing
historical research, but as
Debra Ann’s case shows, they can sometimes reveal unknown and surprising results
that a paper trail may
not expose.
Currently there are three main types of tests that can benefit a genealogical search
for Native American
ancestry: mtDNA, Y-chromosome and genome-wide. Each test yields different results.
Before you choose
to pursue genetic testing it is important to understand how each test works, what
kind of information it can
provide, as well as its informational limitations. This will help you determine
if genetic ancestry testing can
enhance your ongoing genealogical research and will help you decide which test will
reveal the most
information for what you are looking for. The authors are, respectively, the co-founder
and communications
director of Trace Genetics, Inc., a genealogy firm that houses the world’s
largest Native American mtDNA
database.
The mitochondrial DNA (mtDNA) test
The mtDNA test traces the ancestry of a person’s direct maternal line (i.e.
mother’s mother’s mother)
through analysis of the mitochondrial genome found within every cell in the body.
This test can identify a
Native American maternal ancestor that lived dozens to hundreds of generations in
the past and the broad
geographic region of origin for that lineage. Mitochondrial DNA is passed from mothers
to daughters and
sons. However, in the next generation, only the daughter will pass down the same
mitochondrial DNA she
received from her mother. Most mtDNA tests operate by sequencing a portion of the
mtDNA genome (400
base pairs of 16,569 total) that is highly informative about ancestry. The mtDNA
test cannot be used to
estimate the percentage of Native American ancestry in an individual because the
mitochondrial genome
represents approximately 0.0005% of a person’s entire genome. This means,
for example, that a person
could have over 90% Native American ancestry but still have a mitochondrial/maternal
lineage that is derived
from Europe. Alternatively, an individual could have over 90% European ancestry
but still have a Native
American mitochondrial/maternal lineage.
Native American individuals belong to one of five major maternal lineages, called
haplogroups: A, B, C, D,
or X. A non-random geographic pattern exists in Native American populations that
corresponds with the
identified lineages (A=Arctic/Sub-Arctic, B=West/Southwest, C, X=Northeast, D=West).
The mtDNA test
can identify the direct maternal lineage of a person and this maternal lineage is
often informative about
geographic ancestry. Frequently asked questions about the Native American mtDNA
test include:
1. If a mtDNA test identifies a person as being haplogroup A, B, C, D or X, what
does this mean?
Being a member of one of these maternal lineages does not definitively prove that
a person has
Native American ancestry because these lineages are found (in low frequencies) in
other regions of
the world. However, identifying the lineage to which one belongs can be very useful.
Many
individuals wish to distinguish between African, European, and Native American ancestry
in their
maternal line. The assignment of an individual’s ancestry to haplogroup A,
B, C, D, or X can be
used to support other forms of information about Native American ancestry such as
family legends
or written records.
2. Can the Native American mtDNA test tell me what tribe I belong to?
With additional analyses from the mtDNA, haplogroups can be divided into haplotypes,
or sub-
lineages within the major lineages, which often allows Trace Genetics to provide
tribal matches.
However, while a tribal match provides strong evidence of an ancestral relationship
with a specific
Native American tribe, it is not conclusive proof that a person is descendant from
that tribe because
historical evidence suggests that Native American populations intermarried with
neighboring tribes.
Therefore, it is possible that what appears to be a tribal-specific match may be
found in neighboring
populations that are not currently represented in the database. The Trace Genetics
Native American
database contains mtDNA sequences from approximately 80 tribes, representing 15%
of the tribes
in North America.
The Y-chromosome DNA Test
The Y-chromosome test traces the ancestry of a person’s direct paternal lineage
(i.e. father’s father’s father)
and can only be taken by males since only males have the Y chromosome (meaning it
is only passed from
fathers to sons). Females who are interested in learning about their paternal lineage
can have their father,
brother, paternal uncle or paternal cousin take the test. Similar to the mtDNA test,
the Y-chromosome test
identifies the geographic region of origin of your paternal lineage. The region
of the Y chromosome
analyzed in this test represents approximately 1.5% of your entire genome and, thus,
this test cannot measure
percentage of Native American ancestry. Nearly all Native American individuals belong
to Y chromosome
haplogroups/lineages C or Q. The distribution of Y chromosome lineages is much less
structured in North
America than the distribution of mtDNA lineages. Broadly, haplogroup C is found
in higher frequency in
populations from northern North America and haplogroup Q is common among most Native
American
groups. The Y-chromosome database is half the size of the mtDNA database such that
less is known about
paternal patterns of geographic or tribal ancestry within North America.
The Autosomal or Genome-wide Test
The autosomal or genome-wide test traces the ancestry of your entire genome (maternal
and paternal) and
provides percentage ancestry in broad geographic and linguistic groupings (not races),
namely Sub-Saharan
African, East Asian, European, and Native American. It should be noted that the
current test offered has
from a 3-12% reported error rate, meaning that any ancestry in these groupings that
is below 12% is not
definitive. In addition, levels of ancestry below 3% may not be detected. This test
operates by screening
approximately 180 genetic markers that show large frequency differences among the
four population samples
comprising the database. The percentage ancestry is a statistical inference determined
by comparing an
individual’s DNA to the database. This test is useful as an initial analysis
for determining the presence or
absence of Native American ancestry.
In general, genetic testing is not useful on its own to determine which tribe an
individual belongs to. A
completely unique “genetic signature” of a tribe is unattainable because
tribes interacted extensively with
neighboring groups in prehistory and did not evolve in isolation from one another.
Therefore, genetic
markers that evolved in a single tribe were likely transferred to neighboring tribes
through intermarriage.
In addition, because these markers develop as a result of infrequent genetic mutations
in a population, not
all individuals within a tribe would exhibit tribal-specific markers. Furthermore,
the decision as to whether
an individual is part of a tribal community is often based on historical or other
non-genetic factors. Native
American tribes use many different factors to justify enrollment in their community
such as percentage blood
quantum of that tribe, being a direct descendant of an enrolled member, being born
in that tribal community,
and/or having a working knowledge of the culture (language and customs). If a community
requires a
minimum percentage of Native American ancestry, DNA-based tests may be able to assist
tribal communities
in enrollment by supplying evidence of this ancestry in potential tribal members,
but DNA-based tests are
not able to identify percentage ancestry at the tribal level.
Given that the accessibility of genetic testing has increased so dramatically in
recent years, it is especially
important to find a firm that is knowledgeable about the uses and limitations of
current test options and are
willing to take the time to explain results in a genealogically useful way. Because
the field of genetic testing
is also progressing and changing so rapidly, it is important to find a company that
keeps up-to-date on the
latest research and has a firm grasp of where genetic ancestry testing is heading.
Ask about the background
of the scientists and their ability to provide well-rounded, in-depth interpretations
of the results. For
example, the two founders of Trace Genetics have their PhDs in molecular anthropology
and focused their
dissertation research on the peopling of the Americas, using both ancient and modern
DNA. This
background allows them to not only understand and perform the genetic tests but
also gives them the
knowledge to place results in a culturally, historically, and anthropologically
relevant context.
Ultimately, if you are considering adding genetic ancestry testing to your Native
American research, the best
thing to do is call the various companies and talk with their customer support staff.
Customer care personnel
should be able to answer all your questions and be willing to spend as much time
as it takes to do so. Genetic
ancestry testing can add a whole new level of detail and dimension to your research
and being well-informed
makes it that much more exciting.
Table 1: Definitions of Important Terms
|
Term
|
Definition
|
mtDNA (mitochondrial DNA)
|
Genetic material found in the mitochondria within a cell and containing genetic
information distinct from the DNA in the nucleus. mtDNA is inherited from the mother
and traces the direct maternal lineage.
|
|
Genome
|
The full complement of genetic information that an individual organism inherits
from his or her parents, approximately 50% from the mother and 50% from the father.
|
|
Haplogroup
|
A lineage defined by shared diagnostic genetic mutations. Human mtDNA lineages are
labeled A-Z and are often regionally specific. Maternal haplogroups predominant
in North and South America are A, B, C, D and X.
|
|
Haplotype
|
A sub-lineage within the haplogroup that is defined by unique genetic mutations.
|
|
Y-chromosome
|
One of the two sex chromosomes. Males have one Y and one X chromosome and females
have two X chromosomes. The Y chromosome is passed from fathers to sons and can
trace the direct paternal lineage.
|
|
Mutation
|
Any heritable change in the DNA sequence.
|
Table 2. Native American Genetic Tests Offered by Trace Genetics
|
Name of Test
|
Description
|
Price
|
Turnaround Time
|
|
Native American mtDNA Test
|
Trace direct maternal lineage
|
$270.00
|
4-6 weeks
|
|
Native American Y-SNP Test
|
Trace direct paternal lineage
|
$200.00
|
4-6 weeks
|
|
DNAPrint 2.5 Autosomal Test
|
Trace % ancestry across broad groups
|
$250.00
|
8-10 weeks
|
For more information contact us at <tracegenetics.com>
or toll free at 1-866-731-2312.
Copyright 2005 © Trace Genetics
