Study findings may lead to new clinical laboratory tests, as well as vaccines and immunotherapies for neurodegenerative diseases
Research into the human genome continues to produce useful new insights. This time, a study led by researchers at Stanford University identified a genetic variation that is believed to help “slow or even stall” progression of neurodegenerative diseases, including Alzheimer’s and Parkinson’s, according to a press release. Because these genetic variations are common, it is likely that diagnostic tests can be developed for use by clinical laboratories.
Researchers at Stanford Medicine led the study which discovered that approximately one in five individuals carry the gene variant, a protective allele identified as DR4 (aka, HLA-DR4). It’s one of a large number of alleles found in a gene known as DRB1.
DRB1 is part of a family of genes collectively known as the human lymphocyte antigen complex or HLA. The HLA-DRB1 gene plays a crucial role in the ability of the immune system to see a cell’s inner contents.
“In an earlier study, we’d found that carrying the DR4 allele seemed to protect against Parkinson’s disease,” said Emmanuel Mignot, MD, PhD (above), Director of the Stanford Center for Narcolepsy, in a Stanford press release. “Now, we’ve found a similar impact of DR4 on Alzheimer’s disease.” Clinical laboratories may soon have new vaccines for both neurodegenerative diseases. (Photo copyright: Stanford University.)
DR4 Found to Impact Both Parkinson’s and Alzheimer’s Diseases
To perform their research, the team examined a large collection of medical and genetic databases from 176,000 people who had either Alzheimer’s or Parkinson’s disease. The people involved in the study were from numerous countries located in East Asia, Europe, the Middle East and South America. Their genomes were then compared with people who did not have the diseases, focusing on the incidence and age of onset.
“In an earlier study we’d found that carrying the DR4 allele seemed to protect against Parkinson’s disease,” said Mignot in the Stanford press release. “Now, we’ve found a similar impact of DR4 on Alzheimer’s disease.”
The team found that about 20% to 30% of people carry DR4, and that they have around a 10% risk reduction for developing the two diseases.
“That this protective factor for Parkinson’s wound up having the same protective effect with respect to Alzheimer’s floored me,” said Emmanuel Mignot, MD, PhD, the Craig Reynolds Professor of Sleep Medicine in the Department of Psychiatry and Behavioral Sciences at Stanford University and the Director of the Stanford Center for Narcolepsy, in the Stanford Medicine press release. “The night after we found that out, I couldn’t sleep.”
The scientists also analyzed data from autopsied brains of more than 7,000 Alzheimer’s patients and discovered that individuals who carry DR4 had fewer neurofibrillary tangles and that those tangles are composed mainly of modified tau proteins, a common biomarker for Alzheimer’s.
The presence of these tangles corresponds with the severity of Alzheimer’s disease. They are not typically seen in Parkinson’s patients, but the Stanford team found that Parkinson’s patients who did carry DR4 experienced later onset of symptoms.
Mignot stated that tau, which is essential in Alzheimer’s, may also play a role in Parkinson’s, but that further research is required to prove its function.
Both diseases are characterized by the progressive loss of certain nerve cells or neurons in the brain and are linked to an accumulation of abnormal proteins. The Stanford researchers suggested that the DR4 gene variant may help protect individuals from Alzheimer’s and Parkinson’s by preventing the buildup of tau proteins.
“This is a very interesting study, providing additional evidence of the involvement of the immune system in the pathogenesis of Alzheimer’s and Parkinson’s,” neurologist Wassim Elyaman, PhD, Assistant Professor of Neurological Sciences in Neurology, the Taub Institute and the Institute for Genomic Medicine at Columbia University, told Live Science.
New Vaccines and Immunotherapies
According to the Alzheimer’s Association, more than six million Americans are currently living with Alzheimer’s disease and approximately one in three Americans die with Alzheimer’s or another dementia.
The Parkinson’s Foundation states that nearly one million Americans are currently living with Parkinson’s disease, and that number is expected to rise to 1.2 million by 2030. Parkinson’s is the second-most common neurodegenerative disease after Alzheimer’s disease.
Even though the genetic analysis of the Stanford research is strong, more immune cell and blood-based research is needed to definitively establish how tau is connected to the two diseases.
This research could have implications for clinical laboratories by giving them biomarkers for a useful new diagnostic test, particularly for diagnosing Alzheimer’s and Parkinson’s.
Further, Mignot suggested that an effective vaccine could delay the onset or slow the progression of both diseases. He hopes to test his hypothesis on genetically modified mice and eventually human subjects.
Findings could lead to deeper understanding of why we age, and to medical laboratory tests and treatments to slow or even reverse aging
Can humans control aging by keeping their genes long and balanced? Researchers at Northwestern University in Evanston, Illinois, believe it may be possible. They have unveiled a “previously unknown mechanism” behind aging that could lead to medical interventions to slow or even reverse aging, according to a Northwestern news release.
Should additional studies validate these early findings, this line of testing may become a new service clinical laboratories could offer to referring physicians and patients. It would expand the test menu with assays that deliver value in diagnosing the aging state of a patient, and which identify the parts of the transcriptome that are undergoing the most alterations that reduce lifespan.
It may also provide insights into how treatments and therapies could be implemented by physicians to address aging.
“I find it very elegant that a single, relatively concise principle seems to account for nearly all of the changes in activity of genes that happen in animals as they change,” Thomas Stoeger, PhD, postdoctoral scholar in the Amaral Lab who led the study, told GEN. Clinical laboratories involved in omics research may soon have new anti-aging diagnostic tests to perform. (Photo copyright: Amaral Lab.)
Possible ‘New Instrument’ for Biological Testing
Researchers found clues to aging in the length of genes. A gene transcript length reveals “molecular-level changes” during aging: longer genes relate to longer lifespans and shorter genes suggest shorter lives, GEN summarized.
The phenomenon the researchers uncovered—which they dubbed transcriptome imbalance—was “near universal” in the tissues they analyzed (blood, muscle, bone, and organs) from both humans and animals, Northwestern said.
According to the National Human Genome Research Institute fact sheet, a transcriptome is “a collection of all the gene readouts (aka, transcript) present in a cell” shedding light on gene activity or expression.
The Northwestern study suggests “systems-level” changes are responsible for aging—a different view than traditional biology’s approach to analyzing the effects of single genes.
“We have been primarily focusing on a small number of genes, thinking that a few genes would explain disease,” said Luis Amaral, PhD, Senior Author of the Study and Professor of Chemical and Biological Engineering at Northwestern, in the news release.
“So, maybe we were not focused on the right thing before. Now that we have this new understanding, it’s like having a new instrument. It’s like Galileo with a telescope, looking at space. Looking at gene activity through this new lens will enable us to see biological phenomena differently,” Amaral added.
In their Nature Aging paper, Amaral and his colleagues wrote, “We hypothesize that aging is associated with a phenomenon that affects the transcriptome in a subtle but global manner that goes unnoticed when focusing on the changes in expression of individual genes.
“We show that transcript length alone explains most transcriptional changes observed with aging in mice and humans,” they continued.
In tissues studied, older animals’ long transcripts were not as “abundant” as short transcripts, creating “imbalance.”
“Imbalance” likely prohibited the researchers’ discovery of a “specific set of genes” changing.
As animals aged, shorter genes “appeared to become more active” than longer genes.
In humans, the top 5% of genes with the shortest transcripts “included many linked to shorter life spans such as those involved in maintaining the length of telomeres.”
Conversely, the researchers’ review of the leading 5% of genes in humans with the longest transcripts found an association with long lives.
Antiaging drugs—rapamycin (aka, sirolimus) and resveratrol—were linked to an increase in long-gene transcripts.
“The changes in the activity of genes are very, very small, and these small changes involve thousands of genes. We found this change was consistent across different tissues and in different animals. We found it almost everywhere,” Thomas Stoeger, PhD, postdoctoral scholar in the Amaral Lab who led the study, told GEN.
In their paper, the Northwestern scientists noted implications for creation of healthcare interventions.
“We believe that understanding the direction of causality between other age-dependent cellular and transcriptomic changes and length-associated transcriptome imbalance could open novel research directions for antiaging interventions,” they wrote.
While more research is needed to validate its findings, the Northwestern study is compelling as it addresses a new area of transcriptome knowledge. This is another example of researchers cracking open human and animal genomes and gaining new insights into the processes supporting life.
For clinical laboratories and pathologists, diagnostic testing to reverse aging and guide the effectiveness of therapies may one day be possible—kind of like science’s take on the mythical Fountain of Youth.
Clinical laboratories and pathology groups may soon have new assays for diagnosis, treatment identification, patient monitoring
It’s here at last! The human Y chromosome now has a full and complete sequence. This achievement by an international team of genetic researchers is expected to open the door to significant insights in how variants and mutations in the Y chromosome are involved in various diseases and health conditions. In turn, these insights could lead to new diagnostic assays for use by clinical laboratories and pathology groups.
Pathologists and clinical laboratories involved in genetic research will understand the significance of this accomplishment. The full Y chromosome sequence “fills in gaps across more than 50% of the Y chromosome’s length, [and] uncovers important genomic features with implications for fertility, such as factors in sperm production,” SciTechDaily noted.
This breakthrough will make it possible for other research teams to gain further understanding of the functions of the Y chromosome and how specific gene variants and mutations contribute to specific health conditions and diseases. In turn, knowledge of those genetic sequences and mutations would give clinical laboratories the assays that help diagnosis, identify relevant therapies, and monitor a patient’s progress.
“When you find variation that you haven’t seen before, the hope is always that those genomic variants will be important for understanding human health,” said Adam Phillippy, PhD, a senior investigator and head of the Genome Informatics Section at the National Human Genome Research Institute, in a press release. Clinical laboratories and anatomic pathology groups may soon have new assays based on the T2T study findings. (Photo copyright: National Human Genome Research Institute.)
Study Background and Recognition
Revolutionary thinking by the Telomere-to-Telomere (T2T) scientists led to the team’s breakthrough. The researchers “applied new DNA sequencing technologies and sequence assembly methods, as well as knowledge gained from generating the first gapless sequences for the other 23 human chromosomes,” SciTechDaily reported.
In 1977, the first complete genome of an organism was sequenced. Thus began the commencement of sequencing technology research. Twenty years ago the first human genome sequence was completed. The result was thanks to years of work through the preferred “chain termination” (aka, Sanger Sequencing) method developed by Fred Sanger and a $2.7 billion contribution from the Human Genome Project, according to a study published in the African Journal of Laboratory Medicine (AJLM).
By 2005, a new era in genomic sequencing emerged. Scientists now employed a technique called pyrosequencing and the change had great benefits. “Massively parallel or next-generation sequencing (NGS) technologies eliminated the need for multiple personnel working on a genome by automating DNA cleavage, amplification, and parallel short-read sequencing on a single instrument, thereby lowering costs and increasing throughput,” the AJLM paper noted.
The new technique brought great results. “Next-generation sequencing technologies have made sequencing much easier, faster and cheaper than Sanger sequencing,” the AJLM study authors noted.
The changes allowed more sequencing to be completed. Nevertheless, more than half of the Y chromosome sequence was still unknown until the new findings from the T2T study, SciTechDaily reported.
Why the TDT Breakthrough Is So Important
“The biggest surprise was how organized the repeats are,” said Adam Phillippy, PhD, a senior investigator and head of the NHGRI. “We didn’t know what exactly made up the missing sequence. It could have been very chaotic, but instead, nearly half of the chromosome is made of alternating blocks of two specific repeating sequences known as satellite DNA. It makes a beautiful, quilt-like pattern.”
Much can be gained in knowing more about the Y chromosome. Along with the X chromosome, it is significant in sexual development. Additionally, current research is showing that genes on the Y chromosome are linked to the risk and severity of cancer.
Might What Comes Next Give Clinical Labs New Diagnostic Tools?
The variety of new regions of the Y chromosome that the T2T team discovered bring into focus several areas of new genetic research. For instance, the “azoospermia factor region, a stretch of DNA containing several genes known to be involved in sperm production” was uncovered, and “with the newly completed sequence, the researchers studied the structure of a set of inverted repeats or palindromes in the azoospermia factor region,” SciTechDaily reported.
“This structure is very important because occasionally these palindromes can create loops of DNA. Sometimes, these loops accidentally get cut off and create deletions in the genome,” said Arang Rhie, PhD, a staff scientist at NHGRI and first author of the Nature study.
Missing regions would challenge the production of sperm, impacting fertility, so being able to finally see a complete sequence will help research in this area.
Scientists are only just beginning to recognize the value of this breakthrough to future genetic research and development. As genetic sequencing costs continue to drop, the T2T research findings could mean new treatment options for pathologists and diagnostic assays for clinical laboratories are just around the corner.
In fact, the UB study suggests traditional anatomical methods for determining the evolutionary relationships between species may not be as accurate as once thought, an article in SciTechDaily reported.
Nevertheless, the UB’s research into convergent evolution is unlocking new insights into how genes evolve over time and this new knowledge may help researchers develop genetic tests that more accurately identify different diseases and health conditions.
Additionally, studies that bring a better understanding of how beneficial genetic mutations work their way into a species’ genome might also aid researchers in developing personalized clinical laboratory testing and therapies based on manipulating a patient’s genetic sequences in ways that would be beneficial.
Gene Sequencing More Accurate at Determining Evolutionary Relationships
The UB study suggests that existing evolutionary (phylogenetic) trees may need to be reconsidered. To put a finer point on the findings, a UB news release on the study states, “determining evolutionary trees of organisms by comparing anatomy rather than gene sequences is misleading.”
The UB scientists used genetic sequencing to quickly—and more cost effectively—determine evolutionary relationships as compared to traditional morphology (anatomy and structure), according to the news release.
They found genetic data that revealed surprising relationships about where the sequenced species originated, and which differed with prior conclusions that were drawn based on the species’ appearance. The findings suggest there may be need to “overturn centuries of scientific work in classifying relation of species by physical traits,” the UB scientists said.
“For over a hundred years, we’ve been classifying organisms according to how they look and are put together anatomically, but molecular data often tells us a rather different story,” said Matthew Wills, PhD (above), Professor of Evolutionary Paleobiology, Milner Center for Education at the University of Bath, in the news release. “Our study proves statistically that if you build an evolutionary tree of animals based on their molecular data, it often fits much better with their geographical distribution.” This new use of genetic sequencing could lead to improved precision medicine treatments and clinical laboratory testing. (Photo copyright: University of Bath.)
Molecular Data Leads to New Insights into Convergent Evolution
The UB study’s use of genetic sequencing led the researchers to a greater understanding of convergent evolution, defined by “a characteristic evolving separately in two genetically unrelated groups of organisms,” according to UB.
For example, wings are a widely developed characteristic. But they are not necessarily a sign of relatedness when it comes to birds, bats, and insects.
“Now with molecular data, we can see that convergent evolution happens all the time—things we thought were closely related often turn out to be far apart on the tree of life,” Wills said, adding, “Individuals within a family don’t always look similar; it’s the same with evolutionary trees, too.”
Family Trees: Morphology Versus Molecular
In their paper, the UB researchers acknowledged the importance of phylogenies (evolutionary history of species) in areas of biology, including medicine. They aimed to study a better way to produce accurate phylogenetic trees.
“Phylogenetic relationships are inferred principally from two classes of data: morphological and molecular,” they wrote, adding, “The superiority of molecular trees has rarely been assessed empirically.”
So, they set out to compare the two approaches to building evolutionary trees:
Traditional morphology analysis, and
Phylogenetic trees developed using molecular data.
Using 48 pairs of morphological and molecular trees, they mapped data geographically.
“We show that, on average, molecular trees provide a better fit to biogeographic data than their morphological counterparts, and that biogeographic congruence increases over research time,” the researchers wrote.
Biogeography a Better Gauge of Relatedness than Anatomy
The study also found animals on molecular trees lived geographically closer as compared to groups on morphological trees.
For example, molecular studies put aardvarks, elephants, golden moles, swimming manatees, and elephant shews in an Afrotheria group, named for Africa, which is where they came from. Therefore, the biogeography matches, however the appearances of these mammals clearly do not, the UB scientists point out.
“What’s most exciting is that we find strong statistical proof of molecular trees fitting better not just in groups like Afrotheria, but across the tree of life in birds, reptiles, insects, and plants,” said Jack Oyston PhD, UB Department of Biology and Biochemistry Research Associate and first author of the study, in the news release.
The researchers believe their findings support the accuracy of genetic-themed trees.
“It being such a widespread pattern makes it much more potentially useful as a general test of different evolutionary trees. But it also shows just how pervasive convergent evolution has been when it comes to misleading us,” Oyston added.
Advantages of Molecular Data
In their Nature Communications Biology paper, the UB scientists wrote that molecular data offer up these advantages over morphology:
Widely available in vast quantity.
Opportunity exists to “search, repurpose, and reanalyze sequenced data alongside novel sequences.”
Less subjectivity in researchers’ analysis.
Well-developed data at the ready and “still in their infancy.”
The University of Bath’s study of convergent evolution, phylogenetic trees, and comparison of molecular data versus morphology, has implications for medical laboratories. Should their research lead to new insights into how genes evolve over time, diagnostics professionals may have new information to identity diseases and work with others to precisely treat patients.
Though the variant poses low risk thanks to modern HIV treatments, the scientists stress the importance of access to early clinical laboratory testing for at-risk individuals
With the global healthcare industry hyper focused on arrival of the next SARS-CoV-2 variant, pathologists and clinical laboratories may be relieved to learn that—though researchers in the Netherlands discovered a previously unknown “highly virulent” strain of HIV—the lead scientist of the study says there’s “no cause for alarm.”
In a news release, researchers at the University of Oxford Big Data Institute said the HIV variant got started in the Netherlands in the 1990s, spread quickly into the 2000s, and that prior to treatment, people with the new virulent subtype B (VB variant) had exceptionally high viral loads compared to people with other HIV variants.
Fortunately, the scientist also found that around 2010, thanks to antiretroviral drug therapy, the severe variant began to decline.
In an interview with NPR, Chris Wymant, PhD, the study’s lead author, said, “People with this variant have a viral load that is three to four times higher than usual for those with HIV. This characteristic means the virus progresses into serious illness twice as fast, and also makes it more contagious.”
Fortunately, he added, “Existing medications work very well to treat even very virulent variants like this one, cutting down on transmission and reducing the chance of developing severe illness.
“Nobody should be alarmed,” he continued. “It responds exactly as well to treatment as HIV normally does. There’s no need to develop special treatments for this variant.”
Wymant is senior researcher in statistical genetics and pathogen dynamics at the Big Data Institute (BDI).
Epidemiologist Chris Wymant, PhD (above), lead author of the Big Data Institute study at Oxford University, says today’s modern HIV antiretroviral drug therapies effectively treat for the “highly viral” HIV VB variant he and his team discovered. “Nobody should be alarmed,” he told NPR. “It responds exactly as well to treatment as HIV normally does.” Nevertheless, he stressed the importance of access to early clinical laboratory testing for at-risk individuals. (Photo copyright: Oxford Big Data Institute.)
In their published study, the BDI researchers reported that their analysis of genetic sequences of the VB variant suggested it “arose in the 1990s from de novo (of new) mutation, not recombination, with increased transmissibility and an unfamiliar molecular mechanism of virulence.
“By the time, they were diagnosed, these individuals were vulnerable to developing AIDS within two to three years. The virus lineage, which has apparently arisen de novo since around the millennium, shows extensive change across the genome affecting almost 300 amino acids, which makes it hard to discern the mechanism for elevated virulence,” the researchers noted.
The researchers analyzed a data set from the project BEEHIVE (Bridging the Epidemiology and Evolution of HIV in Europe and Uganda). They found 15 of 17 people positive for the VB variant residing in the Netherlands. That prompted them to focus on a cohort of more than 6,700 Dutch HIV positive people in the ATHENA (AIDS Therapy Evaluation in the Netherlands) cohort database, where they found 92 more individuals with the VB variant, bringing the total to 109.
According to a Medscape report on the study’s findings, people with the VB variant showed the following characteristics:
Double the rate of CD4-positive T-cell declines (indicator of immune system damage by HIV), compared to others with subtype-B strains.
Increased risk of infecting others with the virus based on transmissibility associated with variant branching.
Wymant says access to clinical laboratory testing is key to curtailing the number of people who contract the VB variant. “Getting people tested as soon as possible, getting them onto treatment as soon as possible, has helped reduce the numbers of this variant even though we didn’t know that it existed,” he told NPR.
The University of Oxford Big Data Institute study is another example of how constantly improving genome sequencing technology allows scientists to dig deeper into genetic material for insights that can advance the understanding of many diseases and health conditions.
