DNA testing for Native American identity and enrollment is clearly problematic on a social,
cultural, and political front. But what about the science behind such tests? There are problems
there too. The tests can fail to detect Native American ancestry in individuals with Native
American ancestors, and incorrectly identify it in others who do not have such ancestors.
First, Native American DNA tests examine only a small proportion of the test taker’s DNA.
Most tests fall into one of two categories: mitochondrial DNA (mtDNA) tests and Y-
chromosome tests. MtDNA tests examine DNA that is inherited only from one’s mother (and
her mother, and her mother before her...). Y-chromosome tests examine DNA that is passed
down from grandfather to father to son (and so on). These tests examine less than 1% of the test
taker’s DNA, and shed light on only one maternal or paternal ancestor. Thus, even if all of your
grandparents were Native American except for your mother’s mother, a mtDNA test would still
fail to detect Native American ancestry.
Second, DNA tests may certify some individuals as having Native American ancestry when in
fact they do not. These tests use the following logic: if a genetic marker is common in Native
Americans, and you have the marker, you are probably Native American. The problem is that
‘common’ is not the same as ‘only found in’ Native Americans. Given the high level of genetic
variation within all human populations, relatively few markers are restricted to a single group
in this way. In fact, not all “Native American” markers used in the DNA tests are actually
found only in Native Americans. Some of the markers are
in Native American
populations, so any individual with those markers
has Native American ancestry.
But because such markers can still be found in non-Native American populations, just at lower
frequencies, Native American DNA tests may falsely identify some individuals as having
Native American ancestry.
Such “false positives” may be responsible for the more perplexing results of these tests. Several
come from DNAPrint’s AncestrybyDNA test, which examines 175 markers found throughout
the genome to estimate the test taker’s “ancestral proportions” (% Native American, %
European, % East Asian, and % African). Based on their test results, DNAPrint claims that most
Mediterranean Europeans, Middle Easterners, Jews, and South Asian Indians have Native
American ancestry. If, however, some of the markers they consider diagnostic of Native
American ancestry are really not, then such results are not accurate and the reliability of this test
is cast into doubt.
Thus, Native American DNA tests do not provide foolproof answers to questions of Native
American ancestry. In many cases, their results are accurate and informative. But in others,
they fail to detect such ancestry in individuals with Native American ancestors, and they
incorrectly identify it in others. The appropriate use of such imperfect tests must be considered
carefully.
Integrated DNA Technologies
Integrated DNA Technologies, Inc. (IDT), headquartered in Coralville, Iowa, is the largest supplier of custom nucleic acids in the U.S., serving the areas of academic research, biotechnology, clinical diagnostics, and pharmaceutical development. IDT's primary business is the manufacturing of custom DNA and RNA oligonucleotides (oligos) for research applications.Joseph Walder, M.D., Ph.D. (Northwestern University), founded Integrated DNA Technologies, Inc. in 1987 through a partnership with Baxter Healthcare Corporation at the University of Iowa Technology Innovation Center business incubator. In its first 10 years, the company grew from a start-up with 10 synthesizing machines to one with more than 500, shipping an average 36,000 custom oligos per day to its over 77,000 customers worldwide, enabling them to test for genetic diseases, discover new drugs, and develop new treatment models tailored to the specific needs of individual patients
Subscribe to:
Posts (Atom)
