genomics
Case Study Unlocks Clues to Rare Resilience to Alzheimer’s Disease
Posted on by Lawrence Tabak, D.D.S., Ph.D.
Biomedical breakthroughs most often involve slow and steady research in studies involving large numbers of people. But sometimes careful study of even just one truly remarkable person can lead the way to fascinating discoveries with far-reaching implications.
An NIH-funded case study published recently in the journal Nature Medicine falls into this far-reaching category [1]. The report highlights the world’s second person known to have an extreme resilience to a rare genetic form of early onset Alzheimer’s disease. These latest findings in a single man follow a 2019 report of a woman with similar resilience to developing symptoms of Alzheimer’s despite having the same strong genetic predisposition for the disease [2].
The new findings raise important new ideas about the series of steps that may lead to Alzheimer’s and its dementia. They’re also pointing the way to key parts of the brain for cognitive resilience—and potentially new treatment targets—that may one day help to delay or even stop progression of Alzheimer’s.
The man in question is a member of a well-studied extended family from the country of Colombia. This group of related individuals, or kindred, is the largest in the world with a genetic variant called the “Paisa” mutation (or Presenilin-1 E280A). This Paisa variant follows an autosomal dominant pattern of inheritance, meaning that those with a single altered copy of the rare variant passed down from one parent usually develop mild cognitive impairment around the age of 44. They typically advance to full-blown dementia around the age of 50 and rarely live past the age of 60. This contrasts with the most common form of Alzheimer’s, which usually begins after age 65.
The new findings come from a team led by Yakeel Quiroz, Massachusetts General Hospital, Boston; Joseph Arboleda-Velasquez, Massachusetts Eye and Ear, Boston; Diego Sepulveda-Falla, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; and Francisco Lopera, University of Antioquia, Medellín, Colombia. Lopera first identified this family more than 30 years ago and has been studying them ever since.
In the new case report, the researchers identified a Colombian man who’d been married with two children and retired from his job as a mechanic in his early 60s. Despite carrying the Paisa mutation, his first cognitive assessment at age 67 showed he was cognitively intact, having limited difficulties with verbal learning skills or language. It wasn’t until he turned 70 that he was diagnosed with mild cognitive impairment—more than 20 years later than the expected age for this family—showing some decline in short-term memory and verbal fluency.
At age 73, he enrolled in the Colombia-Boston biomarker research study (COLBOS). This study is a collaborative project between the University of Antioquia and Massachusetts General Hospital involving approximately 6,000 individuals from the Paisa kindred. About 1,500 of those in the study carry the mutation that sets them up for early Alzheimer’s. As a member of the COLBOS study, the man underwent thorough neuroimaging tests to look for amyloid plaques and tau tangles, both of which are hallmarks of Alzheimer’s.
While this man died at age 74 with Alzheimer’s, the big question is: how did he stave off dementia for so long despite his poor genetic odds? The COLBOS study earlier identified a woman with a similar resilience to Alzheimer’s, which they traced to two copies of a rare, protective genetic variant called Christchurch. This variant affects a gene called apolipoprotein E (APOE3), which is well known for its influence on Alzheimer’s risk. However, the man didn’t carry this same protective variant.
The researchers still thought they’d find an answer in his genome and kept looking. While they found several variants of possible interest, they zeroed in on a single gene variant that they’ve named Reelin-COLBOS. What helped them to narrow it down to this variant is the man also had a sister with the Paisa mutation who only progressed to advanced dementia at age 72. It turned out, in addition to the Paisa variant, the siblings also shared an altered copy of the newly discovered Reelin-COLBOS variant.
This Reelin-COLBOS gene is known to encode a protein that controls signals to chemically modify tau proteins, which form tangles that build up over time in the Alzheimer’s brain and have been linked to memory loss. Reelin is also functionally related to APOE, the gene that was altered in the woman with extreme Alzheimer’s protection. Reelin and APOE both interact with common protein receptors in neurons. Together, the findings add to evidence that signaling pathways influencing tau play an important role in Alzheimer’s pathology and protection.
The neuroimaging exams conducted when the man was age 73 have offered further intriguing clues. They showed that his brain had extensive amyloid plaques. He also had tau tangles in some parts of his brain. But one brain region, called the entorhinal cortex, was notable for having a very minimal amount of those hallmark tau tangles.
The entorhinal cortex is a hub for memory, navigation, and the perception of time. Its degeneration also leads to cognitive impairment and dementia. Studies of the newly identified Reelin-COLBOS variant in Alzheimer’s mouse models also help to confirm that the variant offers its protection by diminishing the pathological modifications of tau.
Overall, the findings in this one individual and his sister highlight the Reelin pathway and brain region as promising targets for future study and development of Alzheimer’s treatments. Quiroz and her colleagues report that they are actively exploring treatment approaches inspired by the Christchurch and Reelin-COLBOS discoveries.
Of course, there’s surely more to discover from continued study of these few individuals and others like them. Other as yet undescribed genetic and environmental factors are likely at play. But the current findings certainly offer some encouraging news for those at risk for Alzheimer’s disease—and a reminder of how much can be learned from careful study of remarkable individuals.
References:
[1] Resilience to autosomal dominant Alzheimer’s disease in a Reelin-COLBOS heterozygous man. Lopera F, Marino C, Chandrahas AS, O’Hare M, Reiman EM, Sepulveda-Falla D, Arboleda-Velasquez JF, Quiroz YT, et al. Nat Med. 2023 May;29(5):1243-1252.
[2] Resistance to autosomal dominant Alzheimer’s disease in an APOE3 Christchurch homozygote: a case report. Arboleda-Velasquez JF, Lopera F, O’Hare M, Delgado-Tirado S, Tariot PN, Johnson KA, Reiman EM, Quiroz YT et al. Nat Med. 2019 Nov;25(11):1680-1683.
Links:
Alzheimer’s Disease & Related Dementias (National Institute on Aging/NIH)
“NIH Support Spurs Alzheimer’s Research in Colombia,” Global Health Matters, January/February 2014, Fogarty International Center/NIS
“COLBOS Study Reveals Mysteries of Alzheimer’s Disease,” NIH Record, August 19, 2022.
Yakeel Quiroz (Massachusetts General Hospital, Harvard Medical School, Boston)
Joseph Arboleda-Velasquez (Massachusetts Eye and Ear, Harvard Medical School, Boston)
Diego Sepulveda-Falla Lab (University Medical Center Hamburg-Eppendorf, Hamburg, Germany)
Francisco Lopera (University of Antioquia, Medellín, Colombia)
NIH Support: National Institute on Aging; National Eye Institute; National Institute of Neurological Disorders and Stroke; Office of the Director
All of Us Research Program Participants Fuel Both Scientific and Personal Discovery
Posted on by Josh Denny, M.D., M.S., All of Us Research Program
The NIH’s All of Us Research Program is a historic effort to create an unprecedented research resource that will speed biomedical breakthroughs, transform medicine and advance health equity. To create this resource, we are enrolling at least 1 million people who reflect the diversity of the United States.
At the program’s outset, we promised to make research a two-way street by returning health information to our participant partners. We are now delivering on that promise. We are returning personalized health-related DNA reports to participants who choose to receive them.
That includes me. I signed up to receive my “Medicine and Your DNA” and “Hereditary Disease Risk” reports along with nearly 200,000 other participant partners. I recently read my results, and they hit home, revealing an eye-opening connection between my personal and professional lives.
First, the professional. Before coming to All of Us, I was a practicing physician and researcher at Vanderbilt University, Nashville, TN, where I studied how a person’s genes might affect his or her response to medications. One of the drug-gene interactions that I found most interesting is related to clopidogrel, a drug commonly prescribed to keep arteries open after a major cardiovascular event, like a heart attack, stroke, or placement of a stent.
People with certain gene variations are not able to process this medication well, leaving them in a potentially risky situation. The patient and their health care provider may think the condition is being managed. But, since they can’t process the medication, the patient’s symptoms and risks are likely to increase.
The impact on patients has been seen in numerous studies, including one that I published with colleagues last year in the Journal of Stroke and Cerebrovascular Disease [1]. We found that stroke risk is three times higher in patients who were poor responders to clopidogrel and treated with the drug following a “mini-stroke”—also known as a transient ischemic attack. Other studies have shown that major cardiovascular events were 50 percent more common in individuals who were poor responders to clopidogrel [2]. Importantly, there are alternative therapies that work well for people with this genetic variant.
Now, the personal. Reading my health-related results, I learned that I carry some of these very same gene variations. So, if I ever needed a medicine to manage my risk of blood clots, clopidogrel would not likely work well for me.
Instead, should I ever need treatment, my provider and I could bypass this common first-line therapy and choose an alternate medicine. Getting the right treatment on the first try could cut my chances of a heart attack in half. The benefits of this knowledge don’t stop with me. By choosing to share my findings with family members who may have inherited the same genetic variations, they can discuss it with their health care teams.
Other program participants who choose to receive results will experience the same process of learning more about their health. Nearly all will get actionable information about how their body may process certain medications. A small percentage, 2 to 3 percent, may learn they’re at higher risk of developing several severe hereditary health conditions, such as certain preventable heart diseases and cancers. The program will provide a genetic counselor at no cost to all participants to discuss their results.
To enroll participants who reflect the country’s diverse population, All of Us partners with trusted community organizations around the country. Inclusion is vitally important in the field of genomics research, where available data have long originated mostly from people of European ancestry. In contrast, about 50 percent of the All of Us’ genomic data come from individuals who self-identify with a racial or ethnic minority group.
More than 3,600 research projects are already underway using data contributed by participants from diverse backgrounds. What’s especially exciting about this “ecosystem” of discovery between participants and researchers is that, by contributing their data, participants are helping researchers decode what our DNA is telling us about health across all types of conditions. In turn, those discoveries will deepen what participants can learn.
Those who have stepped up to join All of Us are the heartbeat of this historic research effort to advance personalized approaches in medicine. Their contributions are already fueling new discoveries in numerous areas of health.
At the same time, making good on our promises to our participant partners ensures that the knowledge gained doesn’t only accumulate in a database but is delivered back to participants to help advance their own health journeys. If you’re interested in joining All of Us, we welcome you to learn more.
References:
[1] CYP2C19 loss-of-function is associated with increased risk of ischemic stroke after transient ischemic attack in intracranial atherosclerotic disease. Patel PD, Vimalathas P, Niu X, Shannon CN, Denny JC, Peterson JF, Chitale RV, Fusco MR. J Stroke Cerebrovasc Dis. 2021 Feb;30(2):105464.
[2] Predicting clopidogrel response using DNA samples linked to an electronic health record. Delaney JT, Ramirez AH, Bowton E, Pulley JM, Basford MA, Schildcrout JS, Shi Y, Zink R, Oetjens M, Xu H, Cleator JH, Jahangir E, Ritchie MD, Masys DR, Roden DM, Crawford DC, Denny JC. Clin Pharmacol Ther. 2012 Feb;91(2):257-263.
Links:
Join All of Us (All of Us/NIH)
NIH’s All of Us Research Program returns genetic health-related results to participants, NIH News Release, December 13, 2022.
NIH’s All of Us Research Program Releases First Genomic Dataset of Nearly 100,000 Whole Genome Sequences, NIH News Release, March 17, 2022.
Funding and Program Partners (All of Us)
Medicine and Your DNA (All of Us)
Clopidogrel Response (National Library of Medicine/NIH)
Hereditary Disease Risk (All of Us)
Preparing for DNA Results: What Is a Genetic Counselor? (All of Us)
Research Projects Directory (All of Us)
Note: Dr. Lawrence Tabak, who performs the duties of the NIH Director, has asked the heads of NIH’s Institutes, Centers, and Offices to contribute occasional guest posts to the blog to highlight some of the interesting science that they support and conduct. This is the 24th in the series of NIH guest posts that will run until a new permanent NIH director is in place.
A More Precise Way to Knock Out Skin Rashes
Posted on by Lawrence Tabak, D.D.S., Ph.D.
The NIH is committed to building a new era in medicine in which the delivery of health care is tailored specifically to the individual person, not the hypothetical average patient as is now often the case. This new era of “precision medicine” will transform care for many life-threatening diseases, including cancer and chronic kidney disease. But what about non-life-threatening conditions, like the aggravating rash on your skin that just won’t go away?
Recently, researchers published a proof-of-principle paper in the journal Science Immunology demonstrating just how precision medicine for inflammatory skin rashes might work [1]. While more research is needed to build out and further refine the approach, the researchers show it’s now technologically possible to extract immune cells from a patient’s rash, read each cell’s exact inflammatory features, and relatively quickly match them online to the right anti-inflammatory treatment to stop the rash.
The work comes from a NIH-funded team led by Jeffrey Cheng and Raymond Cho, University of California, San Francisco. The researchers focused their attention on two inflammatory skin conditions: atopic dermatitis, the most common type of eczema, which flares up periodically to make skin red and itchy, and psoriasis vulgaris. Psoriasis causes skin cells to build up and form a scaly rash and dry, itchy patches. Together, atopic dermatitis and psoriasis vulgaris affect about 10 percent of U.S. adults.
While the rashes caused by the two conditions can sometimes look similar, they are driven by different sets of immune cells and underlying inflammatory responses. For that reason, distinct biologic therapies, based on antibodies and proteins made from living cells, are now available to target and modify the specific immune pathways underlying each condition.
While biologic therapies represent a major treatment advance for these and other inflammatory conditions, they can miss their targets. Indeed, up to half of patients don’t improve substantially on biologics. Part of the reason for that lack of improvement is because doctors don’t have the tools they need to make firm diagnoses based on what precisely is going on in the skin at the molecular and cellular levels.
To learn more in the new study, the researchers isolated immune cells, focusing primarily on T cells, from the skin of 31 volunteers. They then sequenced the RNA of each cell to provide a telltale portrait of its genomic features. This “single-cell analysis” allowed them to capture high-resolution portraits of 41 different immune cell types found in individual skin samples. That’s important because it offers a much more detailed understanding of changes in the behavior of various immune cells that might have been missed in studies focused on larger groupings of skin cells, representing mixtures of various cell types.
Of the 31 volunteers, seven had atopic dermatitis and eight had psoriasis vulgaris. Three others were diagnosed with other skin conditions, while six had an indeterminate rash with features of both atopic dermatitis and psoriasis vulgaris. Seven others were healthy controls.
The team produced molecular signatures of the immune cells. The researchers then compared the signatures from the hard-to-diagnose rashes to those of confirmed cases of atopic dermatitis and psoriasis. They wanted to see if the signatures could help to reach clearer diagnoses.
The signatures revealed common immunological features as well as underlying differences. Importantly, the researchers found that the signatures allowed them to move forward and classify the indeterminate rashes. The rashes also responded to biologic therapies corresponding to the individuals’ new diagnoses.
Already, the work has identified molecules that help to define major classes of human inflammatory skin diseases. The team has also developed computer tools to help classify rashes in many other cases where the diagnosis is otherwise uncertain.
In fact, the researchers have launched a pioneering website called RashX. It is enabling practicing dermatologists and researchers around the world to submit their single-cell RNA data from their difficult cases. Such analyses are now being done at a small, but growing, number of academic medical centers.
While precision medicine for skin rashes has a long way to go yet before reaching most clinics, the UCSF team is working diligently to ensure its arrival as soon as scientifically possible. Indeed, their new data represent the beginnings of an openly available inflammatory skin disease resource. They ultimately hope to generate a standardized framework to link molecular features to disease prognosis and drug response based on data collected from clinical centers worldwide. It’s a major effort, but one that promises to improve the diagnosis and treatment of many more unusual and long-lasting rashes, both now and into the future.
Reference:
[1] Classification of human chronic inflammatory skin disease based on single-cell immune profiling. Liu Y, Wang H, Taylor M, Cook C, Martínez-Berdeja A, North JP, Harirchian P, Hailer AA, Zhao Z, Ghadially R, Ricardo-Gonzalez RR, Grekin RC, Mauro TM, Kim E, Choi J, Purdom E, Cho RJ, Cheng JB. Sci Immunol. 2022 Apr 15;7(70):eabl9165. {Epub ahead of publication]
Links:
The Promise of Precision Medicine (NIH)
Atopic Dermatitis (National Institute of Arthritis and Musculoskeletal and Skin Diseases /NIH)
Psoriasis (NIAMS/NIH)
RashX (University of California, San Francisco)
Raymond Cho (UCSF)
Jeffrey Cheng (UCSF)
NIH Support: National Institute of Arthritis and Musculoskeletal and Skin Diseases; National Center for Advancing Translational Sciences
All of Us: Release of Nearly 100,000 Whole Genome Sequences Sets Stage for New Discoveries
Posted on by Joshua Denny, M.D., M.S., and Lawrence Tabak, D.D.S., Ph.D.
Nearly four years ago, NIH opened national enrollment for the All of Us Research Program. This historic program is building a vital research community within the United States of at least 1 million participant partners from all backgrounds. Its unifying goal is to advance precision medicine, an emerging form of health care tailored specifically to the individual, not the average patient as is now often the case. As part of this historic effort, many participants have offered DNA samples for whole genome sequencing, which provides information about almost all of an individual’s genetic makeup.
Earlier this month, the All of Us Research Program hit an important milestone. We released the first set of nearly 100,000 whole genome sequences from our participant partners. The sequences are stored in the All of Us Researcher Workbench, a powerful, cloud-based analytics platform that makes these data broadly accessible to registered researchers.
The All of Us Research Program and its many participant partners are leading the way toward more equitable representation in medical research. About half of this new genomic information comes from people who self-identify with a racial or ethnic minority group. That’s extremely important because, until now, over 90 percent of participants in large genomic studies were of European descent. This lack of diversity has had huge impacts—deepening health disparities and hindering scientific discovery from fully benefiting everyone.
The Researcher Workbench also contains information from many of the participants’ electronic health records, Fitbit devices, and survey responses. Another neat feature is that the platform links to data from the U.S. Census Bureau’s American Community Survey to provide more details about the communities where participants live.
This unique and comprehensive combination of data will be key in transforming our understanding of health and disease. For example, given the vast amount of data and diversity in the Researcher Workbench, new diseases are undoubtedly waiting to be uncovered and defined. Many new genetic variants are also waiting to be identified that may better predict disease risk and response to treatment.
To speed up the discovery process, these data are being made available, both widely and wisely. To protect participants’ privacy, the program has removed all direct identifiers from the data and upholds strict requirements for researchers seeking access. Already, more than 1,500 scientists across the United States have gained access to the Researcher Workbench through their institutions after completing training and agreeing to the program’s strict rules for responsible use. Some of these researchers are already making discoveries that promote precision medicine, such as finding ways to predict how to best to prevent vision loss in patients with glaucoma.
Beyond making genomic data available for research, All of Us participants have the opportunity to receive their personal DNA results, at no cost to them. So far, the program has offered genetic ancestry and trait results to more than 100,000 participants. Plans are underway to begin sharing health-related DNA results on hereditary disease risk and medication-gene interactions later this year.
This first release of genomic data is a huge milestone for the program and for health research more broadly, but it’s also just the start. The program’s genome centers continue to generate the genomic data and process about 5,000 additional participant DNA samples every week.
The ultimate goal is to gather health data from at least 1 million or more people living in the United States, and there’s plenty of time to join the effort. Whether you would like to contribute your own DNA and health information, engage in research, or support the All of Us Research Program as a partner, it’s easy to get involved. By taking part in this historic program, you can help to build a better and more equitable future for health research and precision medicine.
Note: Joshua Denny, M.D., M.S., is the Chief Executive Officer of NIH’s All of Us Research Program.
Links:
All of Us Research Program (NIH)
Join All of Us (NIH)
Seeking Consensus on the Use of Population Descriptors in Genomics
Posted on by Eric Green, M.D., Ph.D., National Human Genome Research Institute
Cataloging and characterizing the thousands of genomic variants—differences in DNA sequences among individuals—across human populations is a foundational component of genomics. Scientists from various disciplinary fields compare the variation that occurs within and between the genomes of individuals and groups. Such efforts include attributing descriptors to population groups, which have historically included the use of social constructs such as race, ethnicity, ancestry, and political geographic location. Like any descriptors, these words do not fully account for the scope and diversity of the human species.
The use of race, ethnicity, and ancestry as descriptors of population groups in biomedical and genomics research has been a topic of consistent and rigorous debate within the scientific community. Human health, disease, and ancestry are all tied to how we define and explain human diversity. For centuries, scientists have incorrectly inferred that people of different races reflect discrete biological groups, which has led to deep-rooted health inequities and reinforced scientific racism.
In recent decades, genomics research has revealed the complexity of human genomic variation and the limitations of these socially derived population descriptors. The scientific community has long worked to move beyond the use of the social construct of race as a population descriptor and provide guidance about agreed-upon descriptors of human populations. Such a need has escalated with the growing numbers of large population-scale genomics studies being launched around the world, including in the United States.
To answer this call, NIH is sponsoring a National Academies of Sciences, Engineering, and Medicine (NASEM) study that aims to develop best practices in the use of race, ethnicity, and genetic ancestry in genomics research. The NASEM study is sponsored by 14 NIH institutes, centers, offices, and programs, and the resulting report will be released in February 2023.
Experts from various fields—including genomics, medicine, and social sciences—are conducting the study. Much of the effort will revolve around reviewing and assessing existing methodologies, benefits, and challenges in the use of race and ethnicity and other population descriptors in genomics research. The ad hoc committee will host three public meetings to obtain input. Look for more information regarding the committee’s next public session planned for April 2022 on the NASEM “Race, Ethnicity, and Ancestry as Population Descriptors in Genomics Research” website.
To further underscore the need for the NASEM study, an NIH study published in December 2021 revealed that the descriptors for human populations used in the genetics literature have evolved over the last 70 years [1]. For example, the use of the word “race” has substantially decreased, while the uses of “ancestry” and “ethnicity” have increased. The study provided additional evidence that population descriptors often reflect fluid, social constructs whose intention is to describe groups with common genetic ancestry. These findings reinforce the timeliness of the NASEM study, with the clear need for experts to provide guidance for establishing more stable and meaningful population descriptors for use in future genomics studies.
The full promise of genomics, including its application to medicine, depends on improving how we explain human genomic variation. The words that we use to describe participants in research studies and populations must be transparent, thoughtful, and consistent—in addition to avoiding the perpetuation of structural racism. The best and most fruitful genomics research demands a better approach.
Reference:
[1] Evolving use of ancestry, ethnicity, and race in genetics research—A survey spanning seven decades. Byeon YJJ, Islamaj R, Yeganova L, Wilbur WJ, Lu Z, Brody LC, Bonham VL. Am J Hum Genet. 2021 Dec 2;108(12):2215-2223.
Links:
Use of Race, Ethnicity, and Ancestry as Population Descriptors in Genomics Research (National Academies of Sciences, Engineering, and Medicine)
“Language used by researchers to describe human populations has evolved over the last 70 years.” (National Human Genome Research Institute/NIH)
Genomic Variation Program (NHGRI)
[Note: Acting NIH Director Lawrence Tabak has asked the heads of NIH’s institutes and centers to contribute occasional guest posts to the blog as a way to highlight some of the cool science that they support and conduct. This is the third in the series of NIH institute and center guest posts that will run until a new permanent NIH director is in place.]
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