Why is the AncestrybyDNA™ test different to other ancestry tests?
AncestrybyDNA™ is a distinctive test stating the percentages of your ancestral makeup specified on markers across your 22 pairs of autosomes (non-sex chromosomes); taking into account contributions from your full range of ancestors. Maternal and paternal lineage tests also offered, only report the maternally inherited mtDNA, or the paternally inherited Y-DNA. These lineage tests provide you with information about your direct maternal and paternal lines, as detailed in the diagram beneath.
Generally race includes both a cultural and biological feature of a person or group of people. Physical attributes between populations are often connected by cultural distinctions; separating these two aspects of race has been demanding. The last few decades there has been progression in several fields of science to quantify the issue by declaring that race is "just a social construct". This may be correct, this would depend what variation between people one is reflecting, it is a fact that there are biological differences between the populations of the world. An obvious example of a biological difference is skin colour. There is a strong genetic aspect to the level of pigmentation in an individual's skin and there are many differences across the various populations. Pigmentation is only skin deep and a basic heritable trait in relation of the complicated environments in how we live and how these environments affect our individual and group quality of life is far beyond our ability to apprehend as scientists.
Biological features of race are mostly based on the genetic structure of human populations. This structure is an established hierarchy from East to West where populations in the Americas and the South Pacific are a subset of the genetic diversity found in Eurasia which itself is a subset of the diversity found in Africa (Shriver and Kittles 2005):
It's evident that the human species is fairly young. As a species, we are deemed most likely to have originated in east Africa, according to most archaeologists, 100,000 to 300,000 years ago, and branched off as groups, multiply, moved, and settled in various locations throughout the world. During these migrations, and in the time since, there has been some degree of independent evolution of the populations that established the various continents of the world. Clear evidence of this evolution can be seen in the differences in allele frequencies at genetic markers. In the main, we see that alleles found in one population are also prevalent in all populations and the alleles that are the most common in one are also common in others. This closeness between populations feature the recent common origin of all populations and strong association between populations during human history. Interestingly, there are examples of genetic markers which are dissimilar between populations and it is these markers, stated as Ancestry Informative Markers (AIMs) that can be detailed to approximate the ancestral origins of a person or population.
Race is a difficult and multivariate construct that we are inclined to over simplify but with our analysis, we are calculating a person's genetic ancestry and not their race. Your DNA has no record of ones political, social, personal or religious values. It's simply a four letter code that accounts all of the changes in the DNA from one generation to the next. Our analysis, we detail those changes, they are like finger prints, unique and very complex.
BioGeographical Ancestry (BGA) – what is this?
BioGeographical Ancestry (BGA) is the phrase specified to the biological or genetic part of race. BGA is a straightforward and objective explanation of the Ancestral origins of a person, in terms of the major population groups. (e.g., European, East Asian, sub-Saharan African, Indigenous American, etc.). BGA estimates are able to signify the mixed nature of many people and populations living today. In many countries across the globe, there has been extensive integration amongst populations that had initially been detached. In the fields of human genetics and anthropology, this integration is known as admixture. BGA estimates can also be understood as individual admixture proportions, which can be stipulated as a series of percentages that add to 100%. For example, an individual may be found to have: 65% European; 19% East Asian; 16% African ancestry, or they may be found to have 100% European ancestry.
BioGeographical Ancestry - how is this estimated?
The AncestrybyDNA™ test uses a number of selected panel of Ancestry Informative Markers (AIMs) that have been categorized in a great number of well-defined population samples. These markers are chosen on the basis of displaying significant differences in frequency between population groups and can enable us to detail the origins of a particular person whose ancestry is unidentified. For example, the Duffy Null allele (FY*0) is very familiar (approaching fixation or an allele frequency of 100%) in all sub-Saharan African populations. An individual with this allele is especially likely to have some level of African ancestry. Once 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 probability is the highest is then taken to be the greatest estimate of the ancestral proportions of that person. Confidence intervals on these point estimates of ancestral proportions are also being taken into account and calculated.
AncestrybyDNA™ test – how accurate is this?
The AncestrybyDNA™ test present your ancestral proportions with years of extensive and collaborative research of populations signifying the 4 ancestral groups. This research acknowledged 144 informative markers in our DNA, called Ancestry Informative Markers (AIMs).
The results give you a 95% confidence interval, which is an indication of the statistical strength of the analysis. Why can it not be 100% accurate? It only possible to be 100% accurate if would travel back through the generations and test each and every one of your ancestors. Since this is not viable, we rely on statistics to deliver a prediction of your most probable ancestry mix.
Scientists who developed the Ancestryby™DNA test have carried out extensive validation studies with various numbers of markers to produce a test that was inexpensively feasible as well as provides the most concentrated statistical data. The first version of the test used 71 markers-today we test 144 markers to obtain a much higher confidence level while keeping prices minimised. In a validation study that used a simulated 100% European population, for example, the test results displayed less than 3.3% of total average contribution from African, Indigenous American, and East Asian ancestry, indicating the level of "statistical noise" that is to be expected from the results.
BGA estimates - how can they be used?
We, at AncestrybyDNA™, judge that an objective evaluation of the biological component of human ancestry is possible and that such research could enhance our lives in a number of ways:
Understanding health variations. Are there genetic contributions to the higher rates of hypertension and diabetes in African Americans or the elevated 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 stimulated to reconnect with ancestors, he or she can unravel the past of their family either to verify family tradition or to investigate forgotten or undiscovered roots.
It allows clients to compare their ancestral proportions to others in their family, town, city, or county 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.
Any medical significance with BGA estimates?
The medical implication of BGA estimate is insignificant. Some diseases are to be found at different frequencies in populations across the globe, hardly any are limited to one group. The usefulness of BGA estimates, in biomedical research, comes from epidemiological analysis where many individuals are analysed together to list very broad statements about differences in risk. Even though these results can be very significant, they have very little meaning regarding the level of risk for any one person in the population.
What are the differences between BGA analysis & mtDNA and Y-chromosomal lineage analysis?
The mtDNA and Y-chromosomal lineage tests present a different view of someone's ancestry. It traces and analyses the direct, unbroken maternal and paternal lines, respectively, reverting back to a common ancestor that lived several thousands of years ago. Although these tests may offer information regarding the origin of some of a person's ancestors, they are partial in that they do not give information about the impact of non-lineal ancestors; for example, spouses along the direct maternal and paternal lines.
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 approximately 250 years and within the time frame of genealogical interest, especially when considering the settlement of North America, because they only look at two (2) chromosomes. Y-chromosomal analysis and mtDNA analysis each could only supply information on a very small proportion of a person's ancestors. Our test relies on sequences throughout your genome, so we can provide more details about a larger number of your ancestors.
Does BGA provide more exact information about ancestry?
The current BGA test that AncestrybyDNA™ is offering provides information on the scope of ancestry on the continental level for most continents, European (which includes European, Middle Eastern and South Asian groups such as Indians), and African, but we distinguish ancestries within Asia and the Pacific Rim by adding East Asian, (which includes the Pacific Islanders) as an additional group and Indigenous American. Since there will also be interest in defining the levels of ancestry within continents (such as distinguishing Japanese from Chinese, or Northern European from Middle Eastern), we are in the development stages of expanding our portfolio of services with a new level of Ancestry Informative Markers that will present more insight into where within a particular continent a persons' ancestors were most originated. Launch of these new services will be coming soon, ensure you bookmark this site for future news!
My results were 83% European and 17% East Asian, and the East Asian part amazed me. How accurate is the 17% part of the findings?
17% East Asian proportions signifies that you most likely share sequence identity with East Asians at some markers of your markers that were analysed. Studies have stipulated that, although there is a quantifiable level of noise in the test, we do see a pattern of minor contribution among certain populations. These findings will be available at a later date.
Your range bars and confidence intervals are also part of your answer. The values within these determined ranges represent other possible outcomes that are statistically significant but are less likely. Therefore, if your range bar on the bar graph includes zero, you should consider that possibility.
What does the significance of a low percentage of admixture, such as 4% Indigenous American or 3% African tell me?
There are two ways for you to validate the value of this estimation:
You could have access to historical records or other heritage information 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 plausible case for East Asian ancestry than either on their own.
You can obtain the admixture proportions for both your father and mother. Let's say you register with 4% African and you want to know whether this 4% is in fault or is accurate. You obtain the admixture proportions from your parents and each is 100% European. The 4% was a result of statistical noise as stated earlier. However, if your mother was 15% African and your father was 100% European, your non-zero percentage of African is likely to be an accurate display of African ancestry.
I believe I may have American Indian heritage, my results show that I am 100% European.
Excluding adoption and paternity concerns, your range bars and confidence intervals are also part of the findings. The values within these specified ranges represent other possible outcomes that are statistically important but are less likely. Therefore, if your range bar on the bar graph includes values greater than zero, you should consider that possibility. In the "results for simulated matings" section of the website, the distribution of scores around expected ideals are detailed. This reveals that a range of results are feasible for a particular pedigree pattern (i.e. 1 Indigenous American Grandparent and 3 European Grandparents). Devoid of direct genetic testing, it is may be undecided that your ancestor was 100% Indigenous American. If you only had one such ancestry in your relatives this would make recognition all that much more complex. In addition, the number of generations between a limited number of ancestors with Indigenous American markers and your self will also persuade the probability of discovering such a connection.
I think I have an American Indian background, but my test results show more East Asian than Indigenous American admixture. Am I mistaken or is the test incorrect?
Your results are detailed to how well you match up to to our reference populations. Your range bars and confidence intervals are also part of your answer. The values within these specified ranges signify other possible outcomes that are statistically important but are less likely. It is feasible that your intervals and ranges include a number of values for both Indigenous American and East Asian populations and this should be measured when questioning these types of results.
5 Generations ago, you had 32 Great Grandparents, all of whom contributed to your genetic makeup. Understanding the contributions from each of these individuals is complex. It is likely that some of these individuals had some minor East Asian factor and their contributions are influencing your results.
I thought I was pure Scandinavian, but my results show minor East Asian admixture. Pease explain?
In our testing we've viewed a great number of samples from Eastern Europe and Scandinavia that show signs of some East Asian admixture. This is most likely due to past migrations and is possibly indicating something about the relations of various groups in those regions. Cultures from these areas travelled to regions of Asia and its deemed not unreasonable that offspring may have been created from some of these movements introducing new genetic markers into the Scandinavian population.
Explain just how accurate are the minor (<10%) admixture scores?
Pedigree studies have revealed that the level of admixture follows identified inheritance patterns, aiding the validity of these low values. As previously stated, the confidence intervals are significant for understanding your results and the scores are the most probable estimates from your DNA. If your confidence interval overlaps zero your value may be within the statistical noise threshold of the test and should be considered a possible result. As the number of markers tested increases the statistical noise should decline as confirmation in the change in confidence interval size involving the 2.0 and 2.5 tests.
Has the science for the AncestrybyDNA™ test been made available in scientific literature?
Parra, E., Marcini, A., Akey, J., Martinson, J., Batzer, M., Cooper, R., Forrester, T., Allison, D., Deka, R., Ferrell, R. and M. Shriver. 1998. Estimating African American Admixture Proportions by Use of Population Specific Alleles.Am. J. Hum. Genet. 63:1839-1851.
Frudakis, T., V Kondragunta, M Thomas, Z Gaskin, S Ginjupalli, S Gunturi, V Ponnuswamy, S Natarajan, and P Nachimuthu. 2003. A Classifier for SNP-Based Inference of Ancestry. Journal of Forensics Sciences. 48(4):771-82.
Parra, E., Kittles, R., Argyropoulos, G., Pfaff, C., Hiester, K., Bonilla, C., Sylvester, N., Parrish-Gause, C., Garvey, W., Jin, L., McKeigue, P., Kamboh, M., Ferrell, R., Pollitzer, W., and M. Shriver.2001. Ancestral Proportions and Admixture Dynamics in Geographically Defined African Americans Living in South Carolina.American Journal of Physical Anthropology 114:18-29.
Pfaff, C., Parra, E., Bonilla, C., Hiester, K., McKeigue, P., Kamboh, M., Hutchinson, R., Ferrell, R., Boerwinkle, E., and M. Shriver.2001. Population Structure in Admixed Populations: Effect of Admixture Dynamics on the Pattern of Linkage Disequilibrium.Am. J. Hum. Genet. 68:198-207.