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Ancestry DNA Testing FAQ
How much does the Ancestry
DNA Test cost?
The Ancestry DNA Test is only $395, call (713)
465-0003 or (888) 337-3372 outside the Houston Area to
order.
What is race?
Race is complex, and in general usage, is both a cultural and
biological feature of a person or group of people. Given the fact
that physical differences between populations are often accompanied
by cultural differences, it has been difficult to separate these
two elements. Over the past few decades there has been a movement
in several fields of science to oversimplify the issue declaring
that race is "merely a social construct". While, indeed
this may often be true, depending on what aspect of variation
between people one is considering, it is also false for many particular
instances of differences between the populations of the world.
One clear example of a biological difference is skin color. Culture
or environment has almost no effect on the level of pigmentation
in a person's skin. Yet there are dramatic differences across
populations. Pigmentation is, however, only skin deep and really
quite simple in light of the complex environments in which we
all live and how these affect our individual and group quality
of life.
It is clear that the human species is relatively young. As a
species, we most likely originated in east Africa 100,000 years
ago, and diverged as groups to settle the globe. During these
migrations, and in the time since, there has been some degree
of independent evolution of the populations that settled the various
continents of the world. The simplest evidence of this evolution
can be seen in the differences in allele frequencies at genetic
markers. Generally, we see that alleles found in one population
are also found in all populations and the alleles that are the
most common in one are also common in others. These similarities
between populations highlight the recent common origin of all
populations. However, there are examples of genetic markers which
are different between populations and it is these markers, called
Ancestry Informative Markers (AIMs), which can be used to estimate
the Ancestral origins of a person or population.
What is BioGeographical Ancestry (BGA)?
BioGeographical Ancestry (BGA) is the term given to the biological
or genetic component of race. BGA is a simple and objective description
of the Ancestral origins of a person, in terms of the major population
groups. (e.g. Native American, East Asian, Indo-European, sub-Saharan
African, etc.) BGA estimates are able to represent the mixed nature
of many people and populations today. In the US, as in many other
countries across the globe, there has been extensive mixing among
populations that had initially been separate. In the fields of
human genetics and anthropology, this mixing is referred to as
admixture. BGA estimates can also be understood as individual
admixture proportions, which take the form of a series of percentages
that add to 100%. For example, a person in question may be found
to have: 75% Indo-European; 15% African; 10% Native American ancestry,
or they may be found to have 100% Indo-European ancestry.
How is BioGeographical Ancestry estimated?
The test uses an especially selected panel of Ancestry Informative
Markers (AIMs) that have been characterized in a large number
of well-defined population samples. These markers are selected
on the bases of showing substantial differences in frequency between
population groups and, as such, can tell us about the origins
of a particular person whose ancestry is unknown. For example,
the Duffy Null allele (FY*0) is very common (approaching fixation
or an allele frequency of 100%) in all sub-Saharan African populations
and is not found outside of Africa. Thus, a person with this allele
is very likely to have some level of African ancestry. After the
analysis of these AIMs, in a sample of a person's DNA, the likelihood
(or probability) that a person is derived from any of the parental
populations and any of the possible mixes of parental populations
is calculated. The population (or combination of populations)
where the likelihood is the highest is then taken to be the best
estimate of the ancestral proportions of the person. Confidence
intervals on these point estimates of ancestral proportions are
also being calculated.
How can BGA estimates be used?
An objective assessment of the biological component of human ancestry
is possible and that such research could enrich our lives in a
number of ways:
Understanding health disparities. Are there genetic contributions
to the higher rates of hypertension and diabetes in African Americans
or the higher rates of dementia in European Americans? If not,
then what are the cultural or environmental differences that underlie
the prevailing differences? Studies of these and other diseases
require independent, objective measures of BioGeographical Ancestry
(BGA).
Estimates of BGA can help reconnect individuals separated by adoption,
or some other event, with their ancestral populations.
Even if a person is not particularly motivated to reconnect with
ancestors, he or she can uncover the past of their family either
to verify family legends or to search for forgotten roots.
In the near future, we hope to allow customers to compare their
ancestral proportions to others in their family, town, city, or
state who have chosen to participate. Because it is based on DNA,
and unlike the census, this new tool will provide the most accurate
demographics data that is possible. We will call this our "personal
demographics" tool.
What is the medical significance of BGA estimates?
The medical significance of BGA estimate is negligible. Although
some diseases are found at different frequencies in populations
across the globe, hardly any are restricted to one group. The
usefulness of BGA estimates, in biomedical research, comes from
epidemiological analyses where many individuals are analyzed together
to make very general statements about differences in risk. Even
though these results can be very significant, they have almost
no meaning regarding the level of risk for any one person in the
population.
How is BGA analysis different from mtDNA
and Y-chromosomal ancestry analysis?
There are several commercially available tests of mtDNA and Y-chromosomal
markers, which have been promoted as a means of learning one's
ancestral origins. Although these tests could provide information
regarding the provenance of some of a person's ancestors, they
are very limited. For example, one generation ago a person has
two ancestors, one mother and one father; five generations ago,
a person has 32 ancestors; while 10 generations ago, a person
has 1024 ancestors. Ten generations is roughly 250 years and within
the time frame of genealogical interest, especially when we are
considering the settlement of North America, because they only
look at two (2) chromosomes. Y-chromosomal analysis and mtDNA
analysis each could only provide information on a very small proportion
of a person's ancestors. Our test relies on sequences throughout
your genome, so we can say more about a greater number of your
ancestors.
Can BGA provide more specific information
about ancestry?
Scientists are in the process of developing a new series of Ancestry
Informative Markers that will provide more insight into where
within a particular continent a persons' ancestors were most likely
derived. This test is expected to be available later in 2003.
My proportions were 95% IndoEuropean and
5% East Asian, and the East Asian part surprised me. How reliable
is the 5% part of the profile?
The 5% East Asian means you most likely share sequence identity
with East Asians. From having run over 1,700 tests we know to
expect a 3% error in your profile, almost all of it originating
at the genotyping step. In rare cases where we have repeated analyses
for a person over many runs, we have observed an error rate as
high as 5%, but this is rare - 2-3% is the norm. Nonetheless,
to be conservative, it is probably best for customers to take
values less than 5% with a grain of salt. They may be significant,
but they may not be. The confidence contours on your triangle
plot show this to be the case - at these low levels, there is
always overlap with 0% for this ancestry proportion. However,
if you have a profile with a low percent for a group, and it interests
you, there are two things you can do to confirm its significance
- which brings us to the next question
How can I confirm the significance of a low
percentage of admixture, such as 4% Native American or 3% African?
There are two ways for you to confirm the value of this estimate:
You may have access to historical records or other provenance
that leads you to confirm or refute the admixture. For example,
if your records suggest that you have a grandparent of East Asian
heritage and you register with the test as of 5% East Asian, the
two observations combined make a stronger case for East Asian
ancestry than either on their own.
You can obtain the admixture proportions for your father and mother.
Lets say you register with 4% African and you want to know whether
this 4% is in error or is accurate. You obtain the admixture proportions
from your parents and each is 100% IndoEuropean. Chances are the
4% was a result of genotyping error. However, if your mother was
15% African and your father was 100% IndoEuropean, your non-zero
percentage of African is likely to be an accurate indicator of
African ancestry. This is similar to option A), where you are
relying on two different sources of information to help you hone
in on the most accurate answer possible. Virtually every test
we have performed on family trees has confirmed these types of
low levels. For example, Dr. Frudakis registers with about 11%
Native American, and his Father registers with about 20%, his
mother about 8% and his sister about 16% Native American. Given
the knowledge from his mother, father and sister, the 11% takes
on a new level of significance.
I think I have American Indian heritage, but
my test results show that I am 100% Indo European.
There are two possibilities, and the first possibility is one
that many people do not like to hear. We don't mean to offend,
but it is a possibility that your suspicion is unfounded. If you
are certain that this is not the case, the second possibility
is that one of your distant ancestors was indeed American Indian
but their genetic contribution to your composition has been diluted
over the generations. This is a function of the genetic law of
independent assortment and probability, and it depends on how
admixed and how distant an ancestor the person is. What your results
show is that, using our pan-genome test, there is no evidence
of Native American ancestry in your DNA. In the future, it may
be possible (with more sensitive and expensive tests) to detect
your very dilute Native American ancestry.
I think I have American Indian heritage,
but my test results show more East Asian than Native American
admixture. Am I wrong or is the test wrong?
Neither - your results are probably reflective of one way this
test will help reshape notions of our common history. The result
is certainly not an indication that the test is inaccurate. Using
our test, most individuals suspecting minority (<50%) American
Indian heritage confirm with Native American admixture. Likewise,
the test results for each of several hundred individuals of known
minority (<50%) African, East Asian or Hispanic ancestry have
confirmed with the appropriate admixture. However, about 10% of
the individuals who believe they have American Indian register
as having East Asian as well as Native American ancestry. Even
more surprising, some register with East Asian ancestry but no
Native American ancestry at all! This result has stirred something
of a controversy.
If you are reasonably certain the ancestor was not him/herself
admixed and was recent in your family tree, there are two other
possibilities. Some of the cases we have processed are probably
explained by Aleut heritage and others are probably explained
by admixture that occurred on the North American continent prior
to European colonization.
Aleuts were the latest to arrive across the Bering straight and
physically, they resemble East Asians more than other Native American
peoples. Our test is enriched for markers that have changed in
frequency as the human species migrated to colonize the planet,
and there are an adequate number that distinguish East Asian from
Native Americans as evidenced by the fact that we detect only
Native American admixture in Hispanics and most American Indians.
However, what if Aleuts arrived by boat or over ice after the
disappearance of the land bridge? Would not the molecular distance
between Aleuts and East Asians be lower than between Aleuts and
other Native Americans? This is a distinct possibility, and since
a test such as ours has never existed before, our results may
be teaching us something about the anthropology of the Aleut group.
The remainder of the cases may reflect significant and recent
East Asian admixture with Native Americans prior to European colonization.
Although highly speculative, this is a very interesting possibility
because several recent publications have propounded the idea that
East Asians were the first to "discover" North America
based on archaeological data ("1421: The Year China Discovered
America by Natalie Danford, William Morrow & Co; January 7,
2003). Furthermore, Asian and Native American ancestries are evident
in Russians and other Europeans (Science Magazine "Genetic
Structure of Human Populations", fig. 1 k=6 references that
Russians and the Adygei both have more non-European ancestry,
primarily East Asian and Native American, in the first figure
and then more Central Asian in the second figure). This idea is
controversial, but if this is true, it may explain your result
to a certain extent. Even so, we simply do not know yet the verity
of this, which tribes harbor East Asian admixture, or even whether
there is a tribe-to-tribe difference at all. As we learn more,
we'll update this FAQ list
I thought I was purely of Scandinavian origin,
but my results show minor East Asian admixture. How is this result
possible?
We have found that many individuals reporting pure Scandinavian
ancestry register with detectable East Asian admixture as well.
This result may obtain through contribution of the Lapps, indigenous
Scandinavians who share physical features, culture and common
history with Northern Asian populations. Because this is the first
ancestry test ever developed to query all of the human DNA, these
results represent original interpretations of the structure inherent
to modern day populations and may have exciting implications for
our understanding of our anthropological history of the Scandinavian
region. If your results show significant East Asian admixture
(greater than 5%), you should rest assured that at the level of
DNA you share some greater affiliation with East Asians. Even
though we cannot go back into time and prove exactly how this
affiliation came to be, the history of the Scandinavian region
gives us an important clue. One excellent example of a genetic
study showing that a particular Scandinavian population has East
Asian ancestry, was carried out by Rick Kittles and collaborators
on a several sample of Finish from different regions of Finland
(Kittles et al. 2000).
Kittles RA, Perola M, Peltonen L, Bergen AW, Aragon RA, Virkkunen
M, Linnoila M, Goldman D, Long JC. (1998) Dual origins of Finns
revealed by Y chromosome haplotype variation. Am J Hum Genet 62:1171-1179.
Start unraveling the mystery of your DNA and heritage today,
call please contact us by phone at (713)
465-0003 or (888) 337-3372 outside the Houston Area to
order your Ancestry DNA Test for only $395.
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