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Genomic Scientists Are Working to Make Human Reference Genome More Inclusive by Expanding the Pangenome

Project aims to create a new pangenome for genetic testing that will ensure better clinical laboratory testing and healthcare outcomes

Recent advances in genetics are motivating some scientists to proclaim the need to update the existing “master human genome”—currently based on a single individual’s genetic sequence—to make it more inclusive. This international research effort will have implications for personalized clinical laboratory testing and precision medicine.

Genetic scientists at the Human Pangenome Reference Consortium (HPRC), a project funded by the National Human Genome Research Institute (NHGRI), are working “to sequence and assemble genomes from individuals from diverse populations in order to better represent [the] genomic landscape of diverse human populations,” according to the organization’s website.

The project plans to evaluate a wide variety of reference genomes and develop a more diverse human pangenome (a multi-genome reference sequence) that will contain a larger cross-section of the human population. The HPRC scientists will be looking at genomes from specific countries, including Denmark, Japan, South Korea, Sweden, and the United Arab Emirates, The Guardian reported.

The increased diversity of reference genetic data will enable genomic researchers to increase the accuracy of precision medicine diagnostics and clinical laboratory testing.

Pui-Yan Kwok, MD, PhD

“One person is not representative of the world,” Pui-Yan Kwok, MD, PhD (above), Henry Bachrach Distinguished Professor, Cardiovascular Research Institute at the University of California, San Francisco, told The Guardian. “As a result, most genome sequencing is fundamentally biased.” And that bias, the researchers claim, affects the accuracy of clinical laboratory treatments and diagnostics. (Photo copyright: UCSF.)

Reference Genome for Genetic Sequencing is Based on One Person

Launched in 1990, The Human Genome Project studied all DNA in a select set of organisms. The project completed its first sequence of the human genome in 2003, which became the reference genome for thousands of genomic discoveries since then.

But there’s a problem.

Although a revolutionary breakthrough in genetic sequencing, that reference genome came from just one person. This means a significant portion of the human population is not represented in genetic research, and that bias, according to some scientists, “limits the kind of genetic variation that can be detected, leaving some patients without diagnoses and potentially without proper treatment,” according to The Guardian.

“Getting the right medicine to the right patient at the right time is the tagline,” Neil Hanchard, MD, DPhil, physician scientist and senior investigator for precision health research at the NHGRI in Bethesda, Maryland, told The Guardian.

The HPRC’s goal is to help mitigate reference biases that could hamper disease diagnoses and ensure all populations receive the best treatments for illness. 

According to its website, the organization’s main purpose includes:

  • Gene sequencing from a diverse set of samples with the newest technologies.
  • Fostering an ecosystem of assembly and pangenome tools.
  • Creating and releasing high-quality assemblies and pangenomes.
  • Embedding a team of scholars to address ethical, legal, and social implications of their work.
  • Forming international partnerships for the research.

HPRC Scientists Find Never-Sequenced Genetic Variants in Africa

Standard gene sequencing works by dividing DNA into tiny portions known as short reads, then sequencing and organizing the reads into a genome using an existing reference as a guide. However, this process renders larger blocks of variants, called structural variants (SVs), more difficult to read or even remain undetected, which can translate to a sequence that does not completely represent personal variations.

In 2019, the HPRC team of scientists analyzed genetic samples from 154 people from various parts of the world and discovered SV content that was missing from their reference sequence. A further study of genetic samples from 338 individuals that examined only extra inserted DNA detected the presence of almost 130,000 new sequences.

More recently, the HPRC researchers sampled 426 individuals from 50 ethnolinguistic groups from Africa and discovered a few million new single nucleotide variants (SNVs). Most of these distinct SNVs derived from populations that had not been previously sampled.

“We haven’t even touched SVs,” Hanchard told The Guardian. “But our preliminary data suggests it’s going to be more of the same.”

If an individual “is from a population quite different from the person from which the genome referenced is derived, there will be more misalignment when their short reads are mapped to the reference,” Pui-Yan Kwok, MD, PhD, Henry Bachrach Distinguished Professor, Cardiovascular Research Institute at the University of California, San Francisco, told The Guardian

“We may miss risk variants in those regions not represented in the reference,” he added.

HPRC Receives Clearance from NHGRI to Continue Research

Hanchard recognizes the benefits of regional references in genomic sequencing and is optimistic about the future of genomics and the ability to sequence more diverse populations.

“I would love to get to a point where everyone feels represented and that this is for them, as much as it is for any particular group,” he told The Guardian. “We are from one humanity, that’s the important part.”

On February 13, the HPRC received concept clearance for renewal of the program from the NHGRI, which plans to commit up to $10 million in total costs per year for the program over the next five years.

Genetic sequencing continues to emerge as a vital tool in the diagnoses and treatment of diseases. Ensuring that as many diverse populations as possible are included in genomic research is an important element for precision medicine and optimal healthcare.

Clinical laboratory managers and pathologists will want to stay updated on these developments, because much of this new knowledge about the pangenome will need to be incorporated when interpreting genetic sequences and developing diagnoses in support of personalized medicine.   

JP Schlingman

Related Information:

The Human Genome Needs Updating. But How Do We Make It Fair?

The Human Pangenome Project: A Global Resource to Map Genomic Diversity

Human Genome Project Fact Sheet

National Advisory Council for Human Genome Research (NACHGR)

Two New York City Hospitals Join New Genetic Study to Perform Whole Genome Sequencing on 100,000 Newborn Babies to Search for 250 Rare Diseases

Global Consortium of Scientists Develop New Whole Genome Sequencing Method That Brings Costs Down to $10 per Genome

US National Institutes of Health All-of-Us Research Program Delivering Genetic Test Results and Personalized Disease Risk Assessments to 155,000 Study Participants

NIH program could lead to new diagnostic biomarkers for clinical laboratory tests across a more diverse segment of US population

In another milestone in the US National Institutes of Health’s (NIH) plan to gather diverse genetic information from one million US citizens and then use that data to inform clinical care in ways consistent with Precision Medicine, the NIH’s All-of-Us Research Program announced in a news release it has “begun returning personalized health-related DNA results” to more than 155,000 study participants.

In addition, those participants who request them will receive genetic reports that detail whether they “have an increased risk for specific health conditions and how their body might process certain medications.”

The All-of-Us program, which began enrolling people in 2018, is one of the world’s largest—if not the largest—project of its kind. It could result in more than a million human whole genome sequences to drive medical research and speed discoveries. Study findings, for example, may produce new biomarkers for clinical laboratory tests and diagnostics.

In 2020, the All-of-Us program “had begun releasing genetic results for ancestry and a small number of nonclinical genetic traits,” according to GenomeWeb. Now, the program is taking on the greater challenge of sharing health-related genetic test results directly with its participants.

“We really wanted to make sure that we are providing a responsible return to our participants,” Anastasia Wise, PhD, All-of-Us Program Director for the Genetic Counseling Resource, told GenomeWeb. “They might get information that’s unexpected,” she explained.

So far, about 10,000 people received the NIH’s invitation and 56% have shown interest in receiving their genetic test results, GenomeWeb noted.

Josh Denny, MD

“Knowledge is powerful,” said Josh Denny, MD (above), Chief Executive Officer, NIH All-of-Us Research Program, in an NIH news release. “By returning health-related DNA information to participants, we are changing the research paradigm, turning it into a two-way street—fueling both scientific and personal discovery that could help individuals navigate their own health,” he added. The NIH’s research could lead to new clinical laboratory precision medicine diagnostics for chronic diseases across a more diverse segment of the US population. (Photo copyright: National Institutes of Health.)

Two Types of Genetic Health Reports

Study participants who provided a blood sample and gave their consent to receiving genomic information may also receive a Hereditary Disease Risk report that includes 59 genes and genetic variants linked to serious and “medically actionable” health conditions.

About 3% to 5% of participants will have findings suggesting a high risk for a genetic disease such as breast and ovarian cancers as indicated by BRCA1 and BRCA2 genes, Medical Xpress reported.

“I kind of shudder to think about what could happen if I hadn’t known this [finding that she has the BRCA2 gene],” said Rachele Peterson, All-of-Us Chief of Staff, who spoke to the Associated Press about her receiving own Hereditary Disease Risk report.

Participants can also choose to receive an All-of-Us Medicine and Your DNA report with insights on seven genes that affect how specific medications are metabolized. This pharmacogenetics report is important for those who could learn, for example, that they have a 50% to 60% greater risk of a second heart attack when they continue to take the standard medication, as opposed to a different medication, Medical Xpress noted.

“The information on metabolizing medication can be particularly important for people who need treatment after a heart attack,” Josh Denny, MD, Chief Executive Officer, NIH All-of-Us Research Program, told Medical Xpress.

“Such transparency of genetic information about a massive group—as well as the genetic information on individuals—can be used to improve patient care and clinical outcomes,” said Robert Michel, Editor-in-Chief of Dark Daily and its sister publication The Dark Report.

“The program provides a roadmap for other healthcare organizations to follow. And this is useful strategic knowledge for clinical laboratory leaders to understand and incorporate into their plans to support precision medicine with genetic testing and whole human genome sequencing,” Michel added.

Rich Genetic Data Across a More Diverse Population

As to its goal to reflect national diversity, NIH reported about 80% of All-of-Us participants reside in communities that have been unrepresented in medical research, and that 50% are part of a racial or ethnic minority group.

In “NIH’s All-of-Us Research Program Offers Free Genetic Testing to Increase Diversity of Its Database,” Dark Daily reported on the NIH’s strategy to increase diversity of its All-of-Us database. At that time, 386,000 people were enrolled with 278,000 consenting to all program steps such as completing surveys, sharing electronic health records (EHR), and giving blood and urine samples. The All-of-Us Research Program has reportedly grown to 560,000 enrollees. 

Another large-scale research program aiming for one million whole genome sequences is the VA’s Million Veteran Program (MVP), which, as Dark Daily noted in “US Department of Veterans Affairs’ Million Veterans Program Receives Its 125,000th Whole Human Genome Sequence from Personalis Inc.,” provides researchers with a rich resource of genetic, health, lifestyle, and military-exposure data collected from questionnaires, medical records, and genetic analyses.

By combining this information into a single database, the MVP promises to advance knowledge about the complex links between genes and health, according to an MVP news release.

Researchers tapping All-of-Us and MVP data may ultimately produce enlightening and impactful study findings, which could enable clinical laboratories to perform new diagnostic precision medicine tests that identify diseases early and save lives.       

Donna Marie Pocius

Related Information:

All-of-Us Research Program Returns Genetic Health-Related Results to Participants

NIU All-of-Us Program Returns First Health-Related Genetic Results to Participants

The All-of-Us Research Program Has analyzed the Results of 155,000 Americans. The Results Are Coming In

Huge US Study Starts Sharing Gene Findings with Participants

NIH’s All-of-Us Study Hits New Milestone: Largest Scale Effort to Provide DNA Results

NIH’s All-of-Us Research Program Returns Health-Related DNA Results to Participants

Department of Veterans Affairs Million Veterans Program Receives Its 125,000 Whole Human Genome Sequence from Personalis, Inc.

NIH’s All-of-Us Research Program Offers Free Genetic Testing to Increase Diversity of Its Database

University of Utah Study Points to Genetic Link for High Risk of Stillbirth

Researchers at the university suggested their findings could lead to new genetic tests that could be offered by medical laboratories

New research conducted at the University of Utah suggests that clinical laboratories may someday be able to deploy genetic tests to indicate whether a couple has a higher-than-average risk of stillbirth.

This is yet another example of how researchers are cracking DNA’s code to understand how certain gene variants may affect the healthcare of offspring. The knowledge produced by this research, as confirmed by additional studies, may lead to genetic markers that medical laboratories can use to diagnose the risk of stillbirth using the parent’s DNA.

The researchers published their study in the British Journal of Obstetrics and Gynaecology (BJOG), titled “Familial Aggregation of Stillbirth: A Pedigree Analysis of a Matched Case–Control Study.”

Jessica Page, MD

“Stillbirth is one of those problems that is so tragic and life-changing,” said study co-author Jessica Page, MD (above). “It is especially frustrating when you don’t have a good answer for why it happens. This knowledge may give us the opportunity to change how we risk stratify people and reduce their risk through prevention.” Should this research be validated, clinical laboratories may soon have new genetics tests to help doctors identify risk for stillbirth. (Photo copyright: Intermountain Healthcare.)

Can Stillbirth be Prevented?

Jessica Page, MD, an assistant professor in the Department of Obstetrics and Gynecology at the University of Utah School of Medical and co-author of the 2022 study, was lead author of a 2018 study that estimated nearly one-fourth of stillbirths are preventable.

“Stillbirth rate reduction has been slow in the US and we think many stillbirths may be potentially preventable,” she said in a university press release. “This is motivating us to look for those genetic factors so we can achieve more dramatic rate reduction.”

According to the press release, the University of Utah researchers found that stillbirth “can be inherited and tends to be passed down through male members of the family. That risk preferentially comes from the mother’s or father’s male relatives—their brothers, fathers, grandfathers, uncles, or male cousins. But the odds of a couple losing a baby to stillbirth are even greater when the condition comes from the father’s side of the family.”

The researchers made this discovery by analyzing data from the Utah Population Database (UPDB), which contains information on eight million people who were born in the state or have other connections there. The database is maintained by the Huntsman Cancer Institute at the University of Utah. It includes genealogical information and health records that allowed the researchers to trace incidence of stillbirths across multiple generations of families.

The researchers examined 9,404 stillbirth cases between 1978 and 2019, along with 18,808 live births that served as controls. They identified 390 multi-generational families with high numbers of stillbirths. Within that group, they looked at incidence of stillbirth among first-, second-, and third-degree relatives of stillborn babies. They then compared those numbers with data from unaffected families.

“We were able to evaluate multigenerational trends in fetal death as well as maternal and paternal lineages to increase our ability to detect a familial aggregation of stillbirth,” said genetic epidemiologist Tsegaselassie Workalemahu, PhD, lead author of the study. “Not many studies have examined inherited genetic risk for stillbirth because of a lack of data. The Utah Population Database allows for a more rigorous evaluation than has been possible in the past.”

Workalemahu described the research as “an important step toward identifying specific genes that increase the risk of stillbirth, which could one day lead to better diagnosis and prevention,” according to the university press release.

One caveat, the press release notes, is that Utah’s population is disproportionately of northern European descent. “Future studies will need to determine whether the trends hold true among people of different races and ethnicities,” it stated.

Call for More Testing

The University of Utah study is part of a larger effort to gain a greater understanding of the causes of stillbirths.

“Researchers and national obstetric groups, including the American College of Obstetricians and Gynecologists and the Society for Maternal-Fetal Medicine, have called on doctors and hospitals to offer a stillbirth evaluation, a systematic assessment that includes placental exams, genetic testing, and autopsies,” states a recent story from ProPublica.

The story notes that “more than 20,000 pregnancies in the US end in stillbirth,” and in one in three of those cases, the cause is not determined.

Drucilla Roberts, MD, an obstetric and perinatal pathologist at Massachusetts General Hospital (MGH), told ProPublica that at a minimum, “the placenta should definitely be evaluated in every stillbirth.” But citing CDC data, the story notes that this is done in only 65% of stillbirths, and autopsies are performed in less than 20%.

“Experts blame the low rates on several factors,” the story states. “Because an autopsy often is performed in the days following a stillbirth, doctors and nurses have to ask families soon after they receive news of the death if they would like one. Many families can’t process the loss, let alone imagine their baby’s body being cut open. What’s more, many doctors aren’t trained in the advantages of an autopsy, or in communicating with parents about the exam.”

One consequence, ProPublica notes, is that clinicians are ill-equipped to advise patients on how to reduce risk in future pregnancies. The story describes the case of Karen Gibbins, MD, a maternal-fetal medicine specialist and an assistant professor of obstetrics and gynecology at the Oregon Health and Science University (OHSU) in Portland.

An Opportunity for Pathologists

Gibbins’ son was stillborn in 2018. She asked for an autopsy and learned that her son “had a rare disease caused by her antibodies attacking the cells in his liver,” the story states. When she became pregnant again, her doctor prescribed antibody infusions and she later gave birth to a healthy son. “If we had not had that autopsy, my third child would have died as well,” she told ProPublica.

This parent’s comment about the value of the autopsy done after her son’s stillbirth identifies an opportunity for the pathology profession. For several decades, health plans have become ever more reluctant to pay for autopsies. Yet, pathologists know the value that autopsies can provide.

The immediate value comes from revealing useful insights about all the health conditions of the deceased. The long-term value comes from the ability to gather the findings across a large number of autopsies that can contribute to new knowledge about health conditions that physicians use to improve the diagnoses of different health conditions.

Thus, with the publication of this peer-reviewed study about the connection between genetic variations and stillbirth, there is the opportunity for some of the nation’s pathology societies to advocate for funding a pilot program to fund more autopsies of stillborn babies, specifically to add more knowledge about the role of gene mutations as a causative factor in stillbirths.

Stephen Beale

Related Information:

Increased Risk for Stillbirth Passed Down Through Fathers, Male Relatives

Familial Aggregation of Stillbirth: A Pedigree Analysis of a Matched Case–Control Study

Potentially Preventable Stillbirth in a Diverse U.S. Cohort

Raising the Bar on Stillbirth Research

Study Finds Genes Might Play Major Factor in Stillbirths

Risk of Stillbirth Linked to Father’s Family History, Study Suggests

After a Stillbirth, an Autopsy Can Provide Answers. Too Few of Them Are Being Performed

Her Child Was Stillborn at 39 Weeks. She Blames a System That Doesn’t Always Listen to Mothers

Nutromics Receives $14M for Development of Lab-on-a-Patch DNA Sensor Platform That Transmits Biometric Data in Real Time from Interstitial Fluid

Similar health monitoring devices have been popular with chronic disease patients and physicians who treat them; this technology may give clinical laboratories a new diagnostic tool

There is an ever-increasing number of companies working to develop lab testing technologies that would be used outside of the traditional clinical laboratory. One such example is Nutromics, an Australia-based medical technology company which recently announced it has raised US $14 million to fund its new lab-on-a-patch platform, according to a company press release.

Nutromics’ lab-on-a-patch device “uses DNA sensor technology to track multiple targets in the human body, including disease biomarkers and hard-to-dose drugs,” according to MobiHealthNews. Notably, Nutromics’ technology uses interstitial fluid as the sample source.

The funding, which is earmarked for clinical trials, research, and continued development of the technology, comes from health technology company Dexcom (through the Dexcom Ventures capital fund), VU Venture Partners, and global investment management firm Artesian Investments.

Nutromics raised $4 million last year to support a manufacturing facility and an initial human clinical trial of its “continuous molecular monitoring (CMM) platform technology that is able to track multiple targets in the human body via a single wearable sensor. The platform provides real-time, continuous molecular-level insights for remote patient monitoring and hospital-at-home systems,” MobiHealthNews reported.

Peter Vranes

“We are aiming to cause a paradigm shift in diagnostic healthcare by essentially developing a lab-on-a-patch. A lack of timely and continuous diagnostic insights can strongly impact outcomes when dealing with critical disease states. With this strategic industry and VC (venture capital) investment in us, we see more confidence in our technology and hope to accelerate our growth,” said entrepreneur and chemical engineer Peter Vranes (above), co-founder and CEO of Nutromics, in a press release. Clinical laboratory leaders have watched similar biometric monitoring devices come to fruition. (Photo copyright: Nutromics.)

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How Nutromics’ Lab-on-a-Patch Works

“Our technology is, in fact, two technologies coming together—a marker and needle. What that does is give us access to fluid under your skin called interstitial fluid. If you’re going to measure something continuously, that’s a really good fluid [to measure],” Vranes told Outcomes Rocket.

Vranes calls the system’s aptamer-based sensor platform technology the “jewel in the crown.” An aptamer is a short sequence of artificial DNA or RNA that binds a specific target molecule. Nutromics’ aptamer sensor, Vranes said, enables targeting of analytes, unlike continuous glucose monitors (CGMs). 

“[CGMs] are limited to metabolites—things that are already in the body like glucose and lactate. We’re not limited to those. We can do a whole range of different targets. And what that gives us is a ‘blue ocean’ opportunity to go in and solve problems in areas that other technologies just can’t solve,” Vranes said.

Nutromics plans to develop multiple aptamer-based sensors that measure a variety of analytes in interstitial fluid, Medtech Insight noted.

Nutromics' wearable DNA sensor lab-on-a-patch

Nutromics’ wearable DNA sensor lab-on-a-patch technology (above) enables monitoring of multiple targets, including disease biomarkers and some medications, MobiHealthNews explained. The wearable patch contains microneedles that painlessly access interstitial fluid under the skin. Collected data is wirelessly transmitted to a software application and integrates with consumer health software and provider platforms, according to Nutromics. Medical laboratories could have a role in collecting this data and adding it other test results from patients using the wearable patch. (Photo copyright: Nutromics.)

Initial Launch Will Include Antibiotic Monitoring

Nutromics expects to initially launch therapeutic monitoring of vancomycin, a glycopeptide antibiotic medication used to treat various bacterial infections. The company says 60% of doses for this prescription antibiotic are not within therapeutic range.

The smart patch enables clinicians to give patients medicine “at the right dose and at the right time,” Sophie Stocker, PhD, a senior hospital scientist at St. Vincent’s Hospital Sydney and Senior Lecturer, University of Sydney School of Pharmacy in New South Wales, Australia, told MobiHealthNews.

Nutromics also envisions opportunity in acute kidney injury (AKI).

Other Research Using Microneedle Patch to Sample Interstitial Fluid

Nutromics is not alone in its use of a microneedle patch to access interstitial fluid (ISF) for diagnostics. In “Researchers at Washington University in St. Louis Use Microneedle Patch with Fluorescent Nanolabels to Detect Biomarkers in Skin’s Interstitial Fluid,” Dark Daily reported how engineers at the McKelvey School of Engineering at Washington University in St. Louis in Missouri have developed a disposable microneedle patch that one day could be a painless alternative to some blood draws for diagnostics tests and health monitoring.

Scientists at the Georgia Institute of Technology and Emory University in Atlanta have been studying interstitial fluid as a source of biomarkers, as compared to blood, for years.

“Interstitial fluid originates in the blood and then leaks out of capillaries to bring nutrients to cells in the body’s tissues. Because interstitial fluid is in direct communication with the cells, it should have information about the tissues themselves beyond what can be measured from testing the blood,” said Mark Prausnitz, PhD, Regents Professor and J. Erskine Love Jr. Chair, Georgia Tech School of Chemical and Biomolecular Engineering, in a 2020 news release announcing results of human trials of microneedle-based ISF sampling.

The scientists published their findings in the journal Science Translational Medicine titled, “Sampling Interstitial Fluid from Human Skin Using a Microneedle Patch.”

“We sampled interstitial fluid from 21 human participants and identified clinically relevant and sometimes distinct biomarkers in interstitial fluid when compared to companion plasma samples based on mass spectrometry analysis,” the scientists wrote.

Clinical laboratory leaders and pathologists will find it useful to monitor the development of diagnostics for use outside the lab. Nutromics is an example of a company developing wearable health technology that painlessly gathers data for lab tests to be conducted in point-of-care and near-patient settings.     

—Donna Marie Pocius

Related Information:

Nutromics Raises US$14 Million For Its Ground-breaking Wearable Diagnostic Platform

Lab-on-a-Patch Maker Nutromics Scores $14M From Dexcom Ventures, Others

Peter Vranes, Co-founder of Nutromics, Nutromics Smart Patch—The Next Evolution of the Continuous Glucose Monitor

Nutromics Raises $14m as Dexcom Signals Move into Wider Sensing Capabilities

Australian Medtech Start-up Nutromics Bags $4M in Pre-Market Funding for Continuous Monitoring Device

Extraction of Largely Unexplored Bodily Fluid Could be a New Source of Biomarkers

Sampling Interstitial Fluid from Human Skin Using a Microneedle Patch

Researchers at Washington University in St. Louis Use Microneedle Patch with Fluorescent Nanolabels to Detect Biomarkers in Skin’s Interstitial Fluid

UK Researchers Believe Somatic Mutations Play Vital Role in Aging, Longevity, and Death

Understanding why some mutations impair normal bodily functions and contribute to cancer may lead to new clinical laboratory diagnostics

New insight into the human genome may help explain the ageing process and provide clues to improving human longevity that can be useful to clinical laboratories and researchers developing cancer diagnostics. A recent study conducted at the Wellcome Sanger Institute in Cambridge, United Kingdom, suggests that the speed of DNA errors in genetic mutations may play a critical role in the lifespan and survival of a species.  

To perform their research, the scientists analyzed genomes from the intestines of 16 mammalian species looking for genetic changes. Known as somatic mutations, these mutations are a natural process that occur in all cells during the life of an organism and are typically harmless. However, some somatic mutations can impair the normal function of a cell and even play a role in causing cancer.

The researchers published their findings in the journal Nature, titled, “Somatic Mutation Rates Scale with Lifespan Across Mammals.”

 Inigo Martincorena, PhD

“Aging is a complex process, the result of multiple forms of molecular damage in our cells and tissues. Somatic mutations have been speculated to contribute to ageing since the 1950s, but studying them had remained difficult,” said Inigo Martincorena, PhD (above), Group Leader, Sanger Institute and one of the authors of the study. Greater understanding of the role DNA mutations play in cancer could lead to new clinical laboratory tools and diagnostics. (Photo copyright: Wellcome Sanger Institute.)

Lifespans versus Body Mass

The mammalian subjects examined in the study incorporated a wide range of lifespans and body masses and included humans, giraffes, tigers, mice, and the highly cancer-resistant naked mole-rat. The average number of somatic mutations at the end of a lifespan was around 3,200 for all the species studied, despite vast differences in age and body mass. It appears that species with longer lifespans can slow down their rate of genetic mutations.

The average lifespan of the humans used for the study was 83.6 years and they had a somatic mutation rate of 47 per year. Mice examined for the research endured 796 of the mutations annually and only lived for 3.7 years.

Species with similar amounts of the mutations had comparable lifespans. For example, the small, naked mole-rats analyzed experienced 93 mutations per year and lived to be 25 years of age. On the other hand, much larger giraffes encountered 99 mutations each year and had a lifespan of 24 years. 

“With the recent advances in DNA sequencing technologies, we can finally investigate the roles that somatic mutations play in ageing and in multiple diseases,” said Inigo Martincorena, PhD, Group Leader, Sanger Institute, one of the authors of the study in a press release. He added, “That this diverse range of mammals end their lives with a similar number of mutations in their cells is an exciting and intriguing discovery.”

The scientists analyzed the patterns of the mutations and found that the somatic mutations accumulated linearly over time. They also discovered that the mutations were caused by similar mechanisms and the number acquired were relatively similar across all the species, despite a difference in diet and life histories. For example, a giraffe is typically 40,000 times larger than a mouse, but both species accumulate a similar number of somatic mutations during their lifetimes.

“The fact that differences in somatic mutation rate seem to be explained by differences in lifespan, rather than body size, suggests that although adjusting the mutation rate sounds like an elegant way of controlling the incidence of cancer across species, evolution has not actually chosen this path,” said Adrian Baez-Ortega, PhD, postdoctoral researcher at the Sanger Institute and one of the paper’s authors, in the press release.

“It is quite possible that every time a species evolves a larger size than its ancestors—as in giraffes, elephants, and whales—evolution might come up with a different solution to this problem. We will need to study these species in greater detail to find out,” he speculated.

Why Some Species Live Longer than Others

The researchers also found that the rate of somatic mutations decreased as the lifespan of each species increased which suggests the mutations have a likely role in ageing. It appears that humans and animals perish after accumulating a similar number of these genetic mutations which implies that the speed of the mutations is vital in ascertaining lifespan and could explain why some species live substantially longer than others.

“To find a similar pattern of genetic changes in animals as different from one another as a mouse and a tiger was surprising. But the most exciting aspect of the study has to be finding that lifespan is inversely proportional to the somatic mutation rate,” said Alex Cagan, PhD, Postdoctoral Fellow at the Sanger Institute and one of the authors of the study in the press release.

“This suggests that somatic mutations may play a role in ageing, although alternative explanations may be possible. Over the next few years, it will be fascinating to extend these studies into even more diverse species, such as insects or plants,” he noted.

Benefit of Understanding Ageing and Death

The scientists believe this study may provide insight to understanding the ageing process and the inevitability and timing of death. They surmise that ageing is likely to be caused by the aggregation of multiple types of damage to the cells and tissues suffered throughout a lifetime, including somatic mutations.

Some companies that offer genetic tests claim their products can predict longevity, despite the lack of widely accepted evidence that such tests are accurate within an acceptable range. Further research is needed to confirm that the findings of the Wellcome Sanger Institute study are relevant to understand the ageing process.

If the results are validated, though, it is probable that new direct-to-consumer (DTC) genetic tests will be developed, which could be a new revenue source for clinical laboratories. 

JP Schlingman

Related Information:

Mystery of Why Humans Die Around 80 May Finally Be Solved

Mutations Across Animal Kingdom Shed New Light on Ageing

Somatic Mutation Rates Scale with Lifespan Across Mammals

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