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Clinical Laboratories and Pathology Groups

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International Team of Scientists Use Genetic Testing to Solve Centuries-Old Mystery of Black Death’s Origin

DNA analysis of early plague victims pinpoints Black Death’s start on Silk Road trading communities in mountain region of what is now modern-day Kyrgyzstan in Central Asia

Microbiologists and clinical laboratory scientists will likely find it fascinating that an international team of scientists may have solved one of history’s greatest mysteries—the origin of the bubonic plague that ravaged Afro-Eurasia in the mid fourteenth century. Also known as the Black Death, the plague killed 60% of the population of Europe, Asia, and North Africa between 1346-1353 and, until now, the original source of this disease has largely gone unsolved.

Using DNA analysis and archeological evidence, a multidisciplinary team of scientists from the Max Planck Institute for Evolutionary Anthropology in Germany, the University of Tubingen in Germany, and the University of Stirling in the United Kingdom traced the pandemic’s origin to North Kyrgyzstan in Central Asia in the late 1330s.

In their study published in the journal Nature, titled, “The Source of the Black Death in Fourteenth-Century Central Eurasia,” the authors outlined their investigation of cemeteries in the Chüy Valley of modern-day Kyrgyzstan. The tombstone inscriptions showed a disproportionally high number of burials dating between 1338 and 1339 with inscriptions stating “pestilence” as the cause of death.

Johannes Krause, PhD
Archeological evidence combined with ancient DNA analysis of early plague victims enabled scientists to pinpoint the Black Death’s origins in Kyrgyzstan. “We have basically located the origin in time and space, which is really remarkable,” geneticist Johannes Krause, PhD (above), Professor at the Max Planck Institute for Evolutionary Anthropology, who co-led the study, told The Guardian. “We found not only the ancestor of the Black Death, but the ancestor of the majority of the plague strains that are circulating in the world today.” These new research findings may help microbiologists and clinical pathologists gain new insights into how current strains of Yersinia pestis can be better diagnosed. (Photo copyright: Max Planck Institute.)

Big Bang of Plague

Using 30 skeletons that were excavated from these cemeteries in the late 1880s and moved to St. Petersburg, Russia, the scientists analyzed the DNA of ancient pathogens recovered from the remains of seven people. They discovered Yersinia pestis (Y. pestis) DNA in three burials from Kara-Djigach, which lies in the foothills of the Tian Shan mountains.

According to another article in Nature, the scientists showed that a pair of full Y. pestis genomes from their data were direct ancestors of strains linked to the Black Death, and that the Kara-Djigach strain was an ancestor of the vast majority of Y. pestis lineages circulating today.

“It was like a big bang of plague,” Krause stated at a press briefing, Nature reported.

The research team concluded that the Tian Shan region was the location where Y. pestis first spread from rodents to people, and that the local marmot colonies likely the prevalent rodent carriers of plague.

“We found that modern strains [of the plague] most closely related to the ancient strain are today found in plague reservoirs around the Tian Shan mountains, so very close to where the ancient strain was found. This points to an origin of Black Death’s ancestor in Central Asia,” Krause explained in a Max Planck Institute news release.

He told Nature that fleas likely passed the marmot-based infection on to humans, sparking a local Kyrgyzstan epidemic. The disease then spread along the Silk Road trade routes, eventually reaching Europe, where rats (and the fleas that they carried) spread the disease. 

Understanding Context of Plague

Writing in The Conversation, Associate Professor of Medieval and Environmental History Philip Slavin, PhD, University of Stirling, who co-authored the study, explained that Kara-Djigach is unlikely to be “the specific source of the pandemic,” but rather that the “disaster started somewhere in the wider Tian Shan area, perhaps not too far from that site,” where marmot colonies were likely the source of the 1338-1339 outbreak.

Making a modern-day comparison, Krause told Nature, “It is like finding the place where all the strains come together, like with coronavirus where we have Alpha, Delta, Omicron all coming from this strain in Wuhan.”

Slavin maintains that understanding the “big evolutionary picture” is key when studying the phenomenon of emerging epidemic diseases.

“It is important to see how these diseases develop evolutionary and historically, and avoid treating different strains as isolated phenomena,” he wrote in The Conversation. “To understand how the diseases develop and get transmitted, it is also crucial to consider the environmental and socioeconomic contexts.”

Scientists have spent centuries debating the source of the Black Death that devastated the medieval world. The multidisciplinary process used by the Slavin/Krause-led team provides a lesson to clinical laboratory managers and pathologists on the important role they play when collaborating with colleagues from different fields on scientific investigations.   

Andrea Downing Peck

Related Information:

Mystery of Black Death’s Origins Solved, Say Researchers

Black Death: How We Solved the Centuries-Old Mystery of Its Origins

Ancient DNA Traces Origin of Black Death

The Source of the Black Death in Fourteenth-Century Central Eurasia

Origins of the Black Death Identified

Popularity of Direct-To-Consumer Genetic Tests Still Growing, Regardless of Concerns from Provider and Privacy Organizations

For blood brothers Quest and LabCorp this is good news, since the two medical laboratory companies perform most of the testing for the biggest DTC genetic test developers

Should clinical laboratories be concerned about direct-to-consumer (DTC) genetic tests? Despite alerts from healthcare organizations about the accuracy of DTC genetic testing—as well as calls from privacy organizations to give DTC customers more control over the use of their genetic data—millions of people have already taken DTC tests to learn about their genetic ancestry. And millions more are expected to send samples of their saliva to commercial DTC companies in the near future.

This growing demand for at-home DTC tests does not appear to be subsiding. And since most of the genetic testing is completed by the two largest lab companies—Quest Diagnostics (NYSE:DGX) and Laboratory Corporation of America (NYSE:LH)—other medical laboratories have yet to find their niche in the DTC industry.

Another factor is the recent FDA authorization allowing DTC company 23andme to report the results of its pharmacogenetic (PGx) test directly to customers without requiring a doctor’s order. For these reasons, this trend looks to be gaining momentum and support from federal governing organizations.

How will clinical pathology laboratories ultimately be impacted?

Data, Data, Where’s the Data?

Dark Daily has reported on DTC genetic testing for many years. According to MIT’s Technology Review, 26 million people—roughly 8% of the US population—have already taken at-home DNA tests. And that number is expected to balloon to more than 100 million in the next 24 months!

“The genetic genie is out of the bottle. And it’s not going back,” Technology Review reports.

The vast majority of the genetic information gathered goes into the databases of just four companies, with the top two—Ancestry and 23andMe—leading by a wide margin. The other two major players are FamilyTreeDNA and MyHeritage, however, Ancestry and 23andMe have heavily invested in online and television advertising, which is paying off.


In an op-ed response to a NYT editorial that warned readers to avoid 23andMe’s DTC genetic testing, 23andMe CEO and co-founder Anne Wojcicki (above) wrote, “We believe that consumers can learn about genetic information without the help of a medical professional, and we have the data to support that claim.” The FDA agreed and in February approved 23andMe to report pharmacogenetic test results directly to its customers. How this will play out for clinical laboratories remains to be seen. (Photo copyright: Inc.com.)

As more people add their data to a given database, the likelihood they will find connections within that database increases. This is called the Network Effect (aka, demand-side economies of scale) and social media platforms grow in a similar manner. Because Ancestry and 23andMe have massive databases, they have more information and can make more connections for their customers. This has made it increasingly difficult for other companies to compete.

Quest Diagnostics and LabCorp do the actual gene sequencing for the top players in the DTC genetic testing sector. The expected wave of new DTC genetic test costumers (74 million in the next 24 months) will certainly have a beneficial revenue impact on those two lab companies.

Why the Explosion in Genetic Testing by Consumers?

In 2013, just over 100,000 people took tests to have their DNA analyzed, mostly using Ancestry’s test, as Dark Daily reported. By 2017, that number had risen to around 12 million, and though Ancestry still had the majority market share, 23andMe was clearly becoming a force in the industry, noted Technology Review.

Given the reports of privacy concerns and the difficulty removing one’s genetic data from the Internet once it is online, why are people so eager to spit in those little tubes? There are several reported reasons, including:

And now there are several health-related reasons as well. For example, the study of pharmacogenetics has led clinicians to understand that certain genes reveal how our bodies process some medications. The FDA’s clearance allows 23andMe to directly inform customers about “genetic variants that may be associated with a patient’s ability to metabolize some medications to help inform discussions with a healthcare provider. The FDA is authorizing the test to detect 33 variants for multiple genes,” the FDA’s press release noted.

Controversy Over DTC Genetic Tests

The use of DTC genetic tests for healthcare purposes is not without scrutiny by regulatory agencies. The FDA removed 23andMe’s original health test from the market in 2013. According to Technology Review, the FDA’s letter was “one of the angriest ever sent to a private company” and said “that the company’s gene predictions were inaccurate and dangerous for those who might not fully understand the results.”

23andMe continues to refine its DTC tests. However, the debate continues. In February of this year, the New York Times (NYT) editorial board published an op-ed warning consumers to be wary of health tests offered by 23andMe, saying the tests “look for only a handful of [genetic] errors that may or may not elevate your risk of developing the disease in question. And they don’t factor into their final analysis other information, like family history.”

Anne Wojcicki, CEO and co-founder of 23andMe, responded with her own op-ed to the NYT, titled, “23andMe Responds: Empowering Consumers.” In her letter, Wojcicki contends that people should be empowered to take control of their own health, and that 23andMe allows them to do just that. “While 23andMe is not a diagnostic test for individuals with a strong family history of disease, it is a powerful and accurate screening tool that allows people to learn about themselves and some for the most common clinically useful genetic conditions,” she wrote.

Nevertheless, privacy concerns remain:

  • Who owns the results, the company or the consumer?
  • Who can access them?
  • What happens to them a year or five years after the test is taken?
  • When they are sold or used, are consumers informed?

Even as experts question the accuracy of DTC genetic testing in a healthcare context, and privacy concerns continue to grow, more people each year are ordering the tests. With predictions of 74 million more tests expected in the next 24 months, it’s certain that the medical laboratories that process those tests will benefit.

-Dava Stewart

Related Information:

More than 26 Million People Have Taken an At-Home Ancestry Test

How a DNA Testing Kit Revealed a Family Secret Hidden for 54 Years

23andMe Sells Data for Drug Search

Why You Should Be Careful About 23andMe’s Health Test

23andMe Responds: Empowering Consumers

Police Are Using Genetic Testing Companies to Track Down Criminals

The Problems with Ancestry DNA Analyses

FDA Authorizes 23andMe to Report Results of Direct-to-Consumer Pharmacogenetics Test to Customers without a Prescription, Bypassing Doctors and Clinical Laboratories

Erasing ‘DNA Footprint’ from the Internet Proves Difficult for Consumers Who Provide Data to Genetic Testing Companies

FDA Authorizes First Direct-To-Consumer Test for Detecting Genetic Variants That May Be Associated with Medication Metabolism

Clinical Laboratories and Research Organizations Are Racing to Get Low-Cost, Handheld DNA Analyzers to Market

Portable devices have potential to analyze DNA and produce results in the field in minutes to hours, eliminating the need to return to a medical laboratory to analyze samples

Pathologists continue to hear about research efforts to create small devices that can perform DNA analysis. In the past year, four research organizations, including one in the United States, one in New Zealand, and two in the U.K., have unveiled several devices that will analyze DNA in the field.

This line of research is of particular interest in developing countries where resources such as electricity for refrigeration are scarce. Some of the DNA testing devices will produce results in minutes to hours, eliminating the need to return to a clinical laboratory to analyze samples.

Mobile Medical Laboratory Designed to Fit in a Pocket (more…)

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