Ancestry DNA Testing:The Science Explained

Ancestry DNA Testing - The Science Explained

Ancestry DNA Testing infers your Biological Ancestry proportions by utilizing novel Single Nucleotide Polymorphisms (SNPs, pronounce SNIPS) called Ancestry Informative Markers (AIMs). Though we are 99.9% identical at the level of our DNA, it is that 0.1% that imparts to us our individuality. AIMs are places in that 0.1% of the human genome that differ in sequence between the world's various populations (most of the 0.1% do not differ in this way), and by reading a persons sequence at these positions it is possible to make a strong inference of their ancestral mix. Using recent genomics advances, scientists have identified the world's only comprehensive set of AIMs. The science behind the tests was published in late 1999, and then again in 2001 and 2002 (Parra et al.1; Pfaff et al. 2; Parra et al., 3 and Frudakis et al. 4). The resulting Ancestry DNA Test is the first product yet developed that enables the determination of individual ancestry proportions (called "admixture ratios") from DNA. Because it uses genetic markers spread throughout all the chromosomes, with unique and specific anthropological characteristics, it is quite a distinct product from STR tests, Y-chromosome tests or mitochondrial DNA tests used in other types of anthropological settings. Prior to this testing, there had existed only one DNA test for "race". It too used markers spread among the chromosomes, but only 8-13 (as opposed to hundreds), and using the test has a number of technical and theoretical limitations. For example, using the common human identity tests (STR tests) for the inference of ancestry, it is not possible to discern the difference between an individual of 60% African, 40% European heritage and an individual of 95% African, 5% European heritage (or any other race/percentage combination). Instead, it is only possible to classify a sample as having been derived from an individual of one group - in this example, the result in both cases would be an African inference. Part of the problem with the existing STR tests is that they suffer from statistical, practical and ethical problems because they use overly-complex markers to rigidly "bin" individuals into single racial groups. Most individuals are, in fact, of mixed racial background, and ANCESTRY is the first test ever capable of revealing the precise ancestral proportions within each individual. As such, the test simply reports proportions, rather than making dubious racial classifications.
Admixture proportions are the precise mixture of ancestry within individuals. For example, though a person may seem to be of African heritage, the person may actually be of 80% African and 20% Indo-European ancestry, or they may be of 95% African and 5% Indo-European ancestry, or some other ratio/mix. ANCESTRY gives the precise answer by querying a large number of positions in the person's DNA and using them to plot the individual along "A Multi-Dimensional Continuum of Ancestry" TM. The test has a sensitivity for sub-Saharan African, Indo-European, East Asian and Native American ancestries.

Our current product, produces 4-dimensional plots for representing individual ancestry proportions in terms of Indo-European, sub-Saharan African, Native American and East Asian. If a person is of significant levels of each of the four, the plot is difficult to represent on paper, but the meaning of the raw data generated from this test is the same and this data is easily presented in a spreadsheet format. If the customer is of three or fewer, they can easily be plotted in the triangle plot, and both this plot and the spreadsheet are provided.

Articles:
1 - 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.
2- 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.
3- 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.
4- Frudakis, T., V Kondragunta, M Thomas, Z Gaskin, S Ginjupalli, S Gunturi, V Ponnuswamy, S Natarajan, and P Nachimuthu. 2002. A Classifier for SNP-Based Racial Inference. In Review, Journal of Forensics Sciences.

Start unraveling the mystery of your DNA and heritage today, 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.

Founded in 1987, Genelex Corporation is accredited by the American Association of Blood Banks (AABB)Parentage Testing Committee in DNA parentage testing since 1992 and is Washington State Medical Test Site No. MTS-3919 CLIA No. 50D0980559. Genelex was accredited by the American Society of Crime Laboratory Directors Laboratory Accreditation Board (ASCLD LAB) in forensic DNA testing from 1998-2003 and has contributed to the validation of National Institute of Standards and Technology (NIST) Standard Reference Materials.