UCSF Genomics Diagnostics Team Uses Next-Gen Sequencing as a ‘Laboratory-Developed Test’ to Reveal an Elusive Pathogen’s DNA and Save a Teen’s Life
It took UCSF physicians just 48 hours to identify the bacteria in cerebrospinal fluid that was causing fourteen-year-old Joshua Osborn’s hydrocephalus and status epilepticus
There’s rich irony in the FDA’s recent announcement that it would move forward with plans to regulate “laboratory-developed tests ” (LDTs) just weeks after the national media published stories about how innovative use of an LDT helped physicians make an accurate diagnosis that saved the life of seriously-ill 14-year old boy.
Pathologists and clinical laboratory managers may be aware of the case of Joshua Osborn. It was a laboratory-developed test that used next-generation gene sequencing in a unique approach that gave his care team the diagnostic information they needed to select the right therapies for his condition.
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Sequencing Developers’ Unprecedented Success Drives More Ambitious Goals For Genomics X Prize
New Genomic X PRIZE goals/subjects accelerate the drive toward personalized medicine
Swift improvements to the accuracy, speed, and lower cost of rapid gene sequencing have caused the sponsors of the globally-known X PRIZE to revamp their offer of a $10 million award to a team that is first to achieve a defined milestone in whole human genome sequencing.
Pathologists and clinical laboratory managers will be interested to learn how, last month, the X PRIZE Foundation announced a number of major changes to the formerly-named Archon Genomics X PRIZE. Most significantly, competition sponsors changed the subject from 100 genomes from unspecified donors, to genomes from 100 healthy centenarians.
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Mount Sinai Researchers Create a “Smart Tweezer” That Can Isolate a Single Bacterium from a Microbiome Sample Prior to Genetic Sequencing
New technology could enable genetic scientists to identify antibiotic resistant genes and help physicians choose better treatments for genetic diseases
Genomic scientists at the Icahn School of Medicine at Mount Sinai Medical Center in New York City have developed what they call a “smart tweezer” that enables researchers to isolate a single bacterium from a patient’s microbiome in preparation for genetic sequencing. Though primarily intended for research purposes, the new technology could someday be used by clinical laboratories and microbiologists to help physicians diagnose chronic disease and choose appropriate genetic therapies.
The researchers designed their new technology—called mEnrich-seq—to improve the effectiveness of research into the complex communities of microorganisms that reside in the microbiomes within the human body. The discovery “ushers in a new era of precision in microbiome research,” according to a Mount Sinai Hospital press release.
“Metagenomics has enabled the comprehensive study of microbiomes. However, many applications would benefit from a method that sequences specific bacterial taxa of interest, but not most background taxa. We developed mEnrich-seq (in which ‘m’ stands for methylation and seq for sequencing) for enriching taxa of interest from metagenomic DNA before sequencing,” the scientists wrote in a paper they published in Nature Methods titled, “mEnrich-seq: Methylation-Guided Enrichment Sequencing of Bacterial Taxa of Interest from Microbiome.”
“Imagine you’re a scientist who needs to study one particular type of bacteria in a complex environment. It’s like trying to find a needle in a large haystack,” said the study’s senior author Gang Fang, PhD (above), Professor of Genetics and Genomic Sciences at Icahn School of Medicine at Mount Sinai Medical Center, in a press release. “mEnrich-seq essentially gives researchers a ‘smart tweezer’ to pick up the needle they’re interested in,” he added. Might smart tweezers one day be used to help physicians and clinical laboratories diagnose and treat genetic diseases? (Photo copyright: Icahn School of Medicine.)
Addressing a Technology Gap in Genetic Research
Any imbalance or decrease in the variety of the body’s microorganisms can lead to an increased risk of illness and disease.
“Imbalance of the normal gut microbiota, for example, have been linked with conditions including inflammatory bowel disease (IBD), irritable bowel syndrome (IBS), obesity, type 2 diabetes, and allergies. Meanwhile, the vaginal microbiome seems to impact sexual and reproductive health,” Inside Precision Medicine noted.
In researching the microbiome, many scientists “focus on studying specific types of bacteria within a sample, rather than looking at each type of bacteria present,” the press release states. The limitation of this method is that a specific bacterium is just one part of a complicated environment that includes other bacteria, viruses, fungi and host cells, each with their own unique DNA.
“mEnrich-seq effectively distinguishes bacteria of interest from the vast background by exploiting the ‘secret codes’ written on bacterial DNA that bacteria use naturally to differentiate among each other as part of their native immune systems,” the press release notes. “This new strategy addresses a critical technology gap, as previously researchers would need to isolate specific bacterial strains from a given sample using culture media that selectively grow the specific bacterium—a time-consuming process that works for some bacteria, but not others. mEnrich-seq, in contrast, can directly recover the genome(s) of bacteria of interest from the microbiome sample without culturing.”
Isolating Hard to Culture Bacteria
To conduct their study, the Icahn researchers used mEnrich-seq to analyze urine samples taken from three patients with urinary tract infections (UTIs) to reconstruct Escherichia coli (E. Coli) genomes. They discovered their “smart tweezer” covered more than 99.97% of the genomes across all samples. This facilitated a comprehensive examination of antibiotic-resistant genes in each genome. They found mEnrich-seq had better sensitivity than standard study methods of the urine microbiome.
They also used mEnrich-seq to selectively examine the genomes of Akkermansia muciniphila (A. muciniphila), a bacterium that colonizes the intestinal tract and has been shown to have benefits for obesity and Type 2 diabetes as well as a response to cancer immunotherapies.
“Akkermansia is very hard to culture,” Fang told GenomeWeb. “It would take weeks for you to culture it, and you need special equipment, special expertise. It’s very tedious.”
mEnrich-seq was able to quickly segregate it from more than 99.7% of A. muciniphila genomes in the samples.
Combatting Antibiotic Resistance Worldwide
According to the press release, mEnrich-seq could potentially be beneficial to future microbiome research due to:
- Cost-Effectiveness: It offers a more economical approach to microbiome research, particularly beneficial in large-scale studies where resources may be limited.
- Broad Applicability: The method can focus on a wide range of bacteria, making it a versatile tool for both research and clinical applications.
- Medical Breakthroughs: By enabling more targeted research, mEnrich-seq could accelerate the development of new diagnostic tools and treatments.
“One of the most exciting aspects of mEnrich-seq is its potential to uncover previously missed details, like antibiotic resistance genes that traditional sequencing methods couldn’t detect due to a lack of sensitivity,” Fang said in the news release. “This could be a significant step forward in combating the global issue of antibiotic resistance.”
More research and clinical trials are needed before mEnrich-seq can be used in the medical field. The Icahn researchers plan to refine their novel genetic tool to improve its efficiency and broaden its range of applications. They also intend to collaborate with physicians and other healthcare professionals to validate how it could be used in clinical environments.
Should all this come to pass, hospital infection control teams, clinical laboratories, and microbiology labs would welcome a technology that would improve their ability to detect details—such as antibiotic resistant genes—that enable a faster and more accurate diagnosis of a patient’s infection. In turn, that could contribute to better patient outcomes.
—JP Schlingman
Related Information:
‘Smart Tweezer’ Can Pluck Out Single Bacterium Target from Microbiome
mEnrich-seq: Methylation-guided Enrichment Sequencing of Bacterial Taxa of Interest from Microbiome
Genomic ‘Tweezer’ Ushers in a New Era of Precision in Microbiome Research
Molecular Tweezers Can Precisely Select Microbiome Bacteria
Identification of DNA Motifs that Regulate DNA Methylation
New Bacterial Epigenetic Sequencing Method Could Be Boon for Complex Microbiome Analyses
Tufts Medicine Study Shows Rapid Whole Genome Sequencing Highly Successful at Screening Newborns for Cancer in Children’s Hospitals
Pathologists and clinical laboratories have an opportunity to help create newborn rWGS programs in their parent hospitals and health systems
Diagnosing disease in infants is particularly difficult using typical clinical laboratory testing and modalities. Thus, the use of rapid Whole Genome Sequencing (rWGS) is gaining acceptance when such a procedure is deemed “medically appropriate” based on the child’s symptoms.
In “Whole Genome Sequencing for Newborns Gains Favor,” Robert Michel, Editor-in-Chief of Dark Daily’s sister publication The Dark Report wrote, “Evidence is swiftly accumulating that use of rapid Whole Genome Sequencing for certain children in NICUs can enable diagnostic insights that guide effective interventions. Further, these pilot rWGS programs in children’s hospitals are showing a solid return on investment because of improved care. It is predicted that more hospitals may soon offer rWGS.”
Michel’s prediction is backed up by a recent study published in JAMA Network titled, “Rapid Whole-Genomic Sequencing and a Targeted Neonatal Gene Panel in Infants with a Suspected Genetic Disorder.”
Conducted at Tufts Medical Center in Boston, the researchers found that “Whole genome tests are nearly twice as good as narrower tests at unearthing genetic abnormalities that can cause disease in infants—the study found 49% of abnormalities, compared to 27% with more commonly used tests targeting particular types of genetic diseases,” the Associate Press reported.
The AP story follows the medical journey of a now 4-year-old who was diagnosed with a rare bleeding disorder. The nearly fatal condition was only caught because broad genetic testing found she suffered from factor XIII deficiency, a blood disorder characterized by the inability to clot properly.
“I’ve been doing clinical trials of babies for over 40 years,” neonatologist Jonathan Davis, MD (above), Chief, Division of Newborn Medicine at Tufts Children’s Hospital at Tufts Medical Center and Professor of Pediatrics, Tufts University School of Medicine, told the AP. “It’s not often that you can do something that you feel is going to really change the world and change clinical practice for everyone.” Clinical laboratories that work with oncologists to treat children suffering from cancer will understand Davis’ enthusiasm. (Photo copyright: Tufts Medicine.)
Incorporating Rapid Whole Genome Sequencing into Infant Care
Genetic diseases are responsible for 41% of infant deaths, according to a Rady Children’s Institute press release, which goes on to say the usage of rWGS may significantly improve the odds for infants born with genetic disorders.
“Broad use of genomic sequencing during the first year of life could have a much greater impact on infant mortality than was recognized hitherto,” said Stephen Kingsmore MD, President/CEO, Rady Children’s Institute for Genomic Medicine, which was one of the additional study sites for the Tufts Medicine researchers.
Genetic testing is already used to predict infant health outcomes, but the Tufts study highlights further developments that could improve the process. Prenatal genetic testing can be utilized both through carrier testing to determine any potential genetic red flags in the parents, and during prenatal screening and diagnostic testing of the fetus.
When an infant presents symptoms after birth, rWGS can then be implemented to cast a broad net to determine the best course of treatment.
According to ScienceDaily, the Tufts study found rWGS “to be nearly twice as effective as a targeted gene sequencing test at identifying abnormalities responsible for genetic disorders in newborns and infants.”
However, the rWGS tests took an average of six days to come back, whereas the targeted tests took only four days, ScienceDaily reported. Also, there is not full consensus on whether a certain gene abnormality is actually the cause of a specific genetic disorder.
“Many neonatologists and geneticists use genome sequencing panels, but it’s clear there are a variety of different approaches and a lack of consensus among geneticists on the causes of a specific patient’s medical disorder,” Jill Maron, MD, Vice Chair of Pediatric Research, Tufts Medical Center, and a co-principal investigator of the Tufts study, told Science Daily.
rWGS Costs versus Return on Investment
Some also question the upfront cost of genetic testing. It can be high, but it’s coming down and Maron stresses the importance of the tests.
“Genome sequencing can be costly, but in this targeted, at-risk population, it proves to be highly informative. We are supportive of ongoing efforts to see these tests covered by insurance,” she told ScienceDaily.
Each of the doctors associated with the Tufts study emphasized the importance of this testing and the good that can be done for this vulnerable group. The potential value to the children, they say, far outweighs the drawbacks of the testing.
“This study provides further evidence that genetic disorders are common among newborns and infants,” Kingsmore told ScienceDaily, “The findings strengthen support for early diagnosis by rapid genomic sequencing, allowing for the use of precision medicine to better care for this vulnerable patient population.”
For clinical laboratories, there is also good news about reimbursement for rWGS. In a story published last fall KFF Health News wrote, “Since 2021, eight state Medicaid programs have added rapid whole-genome sequencing to their coverage or will soon cover it, according to GeneDX, a provider of the test. That includes Florida … The test is also under consideration for coverage in Georgia, Massachusetts, New York, and North Carolina, according to the nonprofit Rady Children’s Institute for Genomic Medicine, another major provider of the test.”
“Collectively, these developments are encouraging children’s hospitals, academic centers, and tertiary care centers to look at establishing their own rWGS programs,” wrote Michel in The Dark Report. “In settings where this is appropriate, hospital and health system-based clinical laboratories have an opportunity to take an active role in helping jump start a newborn rWGS program in their institutions.”
Pathologists should continue to monitor rWGS, as well as prenatal and carrier testing, to have a full awareness of its growing use in infant and young child cancer screening.
—Ashley Croce
Related Information:
A Broad Genetic Test Saved One Newborn’s Life. Research Suggests it Could Help Millions of Others
Whole Genome Sequencing for Newborns Gains Favor
Prenatal Genetic Screening Tests
Genome Sequencing Highly Effective at Diagnosing Genetic Disorders in Newborns and Infants
Rapid Whole Genome Sequencing Has Clinical Utility in Children in the Pediatric Intensive Care Unit
