Whole Genome Sequencing

My raw DNA data file from a given autosomal test provider is not a record of my entire genome. It lacks certain genetic markers and only covers those relevant for the company's algorithms. Moreover, my biogeographical admixture is not 100% accurate because of the test provider's use of imputation to estimate missing genotype information. Imputation is a process by which gaps in one's genome which weren't sequenced can be inferred. As a result, some of my ancestry calculations could be skewed and vary from company to company.

To compensate for this, the pie chart in Figure 4 reflects Next Generation Sequencing (NGS) technology to read out my entire human genome. This process is referred to as Whole Genome Sequencing. It reports the autosomal test results from Nebula Lab's whole genome sequencing, which covers ~ 1.3 billion sequenced bases out of ~ 3 billion base pairs in the human genome and is 99% accurate and results in one thousand times more data than tests that use microarray-based genotyping. The Nebula test enables imputation (prediction) of unsequenced positions with an accuracy that is sufficiently high for most use cases. "In comparison, such labs as 23andMe and AncestryDNA, which use microarray-based genotyping that reads the human genome at only ~500,000 positions" in comparison to the 0.4x coverage (~ 1.3 billion positions) by Nebula Genomics. Additionally, unlike DNA microarrays, low-coverage WGS can discover novel genetic variants and it produces more accurate results for those with no or little European ancestry.

Figure 4
My Ethnic Genetic Ancestry
Nebula Whole Genome Sequencing


Note Figure 4 depicts my genetic ancestry at the continental level, which is generally considered to be reliable. Beyond that, there are limitations. According to genetic genealogist Blaine Bettinger, "the ethnicity estimate is good on the continent level; getting down to the country or region is much more problematic." And, writing in Live Science, Ker Than adds, "Such tests also cannot account for recent migrations of peoples from their ancient homelands. "Present-day patterns of residence are rarely identical to what existed in the past, and social groups have changed over time, in name and composition." Noted geneticist, Adam Rutherford, recently wrote in the prestigious magazine, Scientific American, "For deeper family roots, these tests do not really tell you where your ancestors came from. They say where DNA like yours can be found on Earth today. By inference, we are to assume that significant proportions of our deep family came from those places. But to say that you are 20 percent Irish, 4 percent Native American or 12 percent Scandinavian is fun, trivial and has very little scientific meaning."

As for genealogical ethnicity, Roberta Estes: adds, "I've said this before, and I want to say it again. Ethnicity is the least precise and the least accurate of DNA tools for genetic genealogy. Ethnicity estimates are the most accurate at a continental level. Within continents, like Europe, Asia and Africa, there has been a lot of population movement and intermixing over time making the term “ethnicity” almost meaningless."

Noted Anthropology professor, Deborah Bolnick, agrees. She says, "If a test-taker is just interested in finding out where there are some people in the world that share the same DNA as them, then these tests can certainly tell them that."

So, with these words in mind, I acknowledge my genetic ancestry inherited from my parentage is broadly accurate at the continental level. Yet, to find out where there are some people in the world with whom I share the same DNA, I present the findings in Table 2.

Table 2
My Reference Populations
Nebula Whole Genome Sequencing

Small amounts of ethnicity at both the continental and within continents can be just statistical noise or incorrect, Roberta Estes warns.


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