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Genetic Linkage

Partial Fetus in Sister’s Brain Supports Role of DNA Repeats in Development

Startling images in the journal Neurology made the media rounds last week. CT scans show a partial fetus wedged within a space (ventricle) in the brain of its one-year-old sister. In photos, the removed potential sibling resembles a pink tadpole.


The report, called a Teaching NeuroImage, is from four researchers at Beijing Tiantan Hospital, and entitled "Intraventricular Fetus-in-Fetu, With Extensive De Novo Gain in Genetic Copy Number." That means the genome of the doomed fetus-within-a-fetus had lots of copies of certain short DNA sequences that aren't in the parents' genomes ("de novo" means new).


With only two short paragraphs, the report doesn't explore the significance of the discovery of the repeat-riddled genome. But I thought immediately of young children with combinations of developmental delay, intellectual disability, autism, learning disabilities, and behavioral conditions that turn out to have microduplications or microdeletions – that is, bits of DNA copied too many times, or missing. Might the partial fetus have had an extreme version of the DNA repeats that are associated with these syndromes, halting development well before birth?


To continue reading, go to DNA Science, where this post first appeared.

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The Dogs of Chernobyl Reveal the Genomic Aftermath of a Human-Made Environmental Disaster

In the original Planet of the Apes, the Forbidden Zone is a future radiation-devastated landscape from which hardy new mutants arise, shifting the evolutionary course of humanity.


The "nuclear exclusion zone" sounds similar, but is real, referring to the 3,004-square-kilometer (about 1,160-square-mile) environs of the Chernobyl nuclear power plant that exploded on April 26, 1986, at 1:23:58 am. The Chernobyl Dog Research Initiative has published their analysis of genetic changes among the dogs who live today in what researchers call the aftermath of "an ecological catastrophe of massive proportions." Gabriella Spatola and Elaine Ostrander of the National Human Genome Research Institute and colleagues report their findings in Science Advances.


Soon after the explosion, as humans fled, workers remained to clean up and to cull the canine population. But some dogs survived, and the workers as well as tourists have cared for them since. Yes, Chernobyl was and remains a tourist destination, by jeep or jet.


An Unnatural Experiment


To continue reading, go to DNA Science, where this post first appeared.

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Rare Disease Day 2023: Isla’s Story and NGLY1 Deficiency

The road to naming an unusual collection of unfolding symptoms is called the "diagnostic odyssey" for good reason: the journey takes, on average, nearly 5 years.


Worldwide, about 400 million people have one of the 10,000 or so recognized rare diseases, or one in ten people, according to Global Genes. About half are children, and 95 percent of the conditions do not have FDA-approved treatments.


In the US, 25 to 30 million people have a rare disease. Ten-year-old Isla Richman is one of them. She has NGLY1 deficiency. Her family shared their story with me in recognition of Rare Disease Day 2023, the last day of February.


To continue reading, go to DNA Science, where this post first appeared.

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Why COVID Vaccines Proliferate as Monoclonal Antibody Drugs Fade

Monoclonal antibody drugs to fight COVID are being taken off the market while new COVID vaccines are arriving, even as the old ones are standing up quite well against new viral variants. How can two interventions that tweak an immune response have such different outlooks? It stems from the biology.


Understanding what antibodies are, how our bodies make them, and how vaccine and monoclonal antibody technologies work and differ, explains the distinction.


The Antibody Response is Naturally Polyclonal


The immune system is a vast army of cells and their secretions that recognize and respond to the presence of "non-self" cells and molecules, like the spike proteins that fringe SARS-CoV-2, the virus behind COVID. One of the first things I learned in college is that "biology is really chemistry," and that's certainly true for the immune response. It's all about recognizing molecules.


To continue reading go to DNA Science, where this post first appeared.

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Why Race-Based Health Care is Bad Medicine: From BiDil to Kidney Transplants

Choosing a medical treatment based on patient traits historically used to define races is fundamentally flawed, because race in the context of humans is a social construct, while medicine is based on biology. Race-based prescribing robs some individuals of drugs that could help them, while prescribing them to people who likely will not respond, or even be harmed. Fortunately, the practice of basing treatment decisions on the superficial traits used to define human races is on the decline.


Blood thinners and blood pressure medications have for decades dominated discussions of race-based prescribing. A more recent example of the dangers of using superficial features as guidelines for providing appropriate care is flawed interpretation of a standard measure of kidney function, used to prioritize patients for kidney transplants. Due to a fudge factor of sorts, until very recently Blacks have been given lower priority on the lists for organs.


Perhaps the starkest example I've encountered of race obscuring delivery of adequate health care comes from California-based pediatrician Richard Garcia, who wrote in The Chronicle of Higher Education in 2003 "The Misuse of Race in Medical Diagnosis":


"My childhood friend Lela wasn't diagnosed with cystic fibrosis until she was 8 years old. Over the years, her doctors had described her as a '2-year-old black female with fever and cough' and 'a 4-year-old black girl with another pneumonia. Lela is back.' Had she been a white child, or had no visible 'race' at all, she would probably have gotten the correct diagnosis and treatment much earlier. Only when she was 8 did a radiologist, who had never seen her face to face, notice her chest X-ray and ask, 'Who's the kid with CF?'"


To continue reading, go to DNA Science, where this post first appeared.

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Science Fairs Counter Science Illiteracy

The pandemic ignited public interest in science, introducing the phrase "doing my research." But the persistence of the idea that science aims to "prove" anything reveals a fundamental misunderstanding of what scientists actually do.


What Science Is, and Isn't


Scientists test hypotheses based on observations of the natural world, then deduce possible explanations, using experiments and further observations. We analyze data, draw tentative conclusions, then ask more questions. The scientific method is, as I've called it in my textbooks, a cycle of inquiry. Variations on the theme are spawned from creative thinking.


So when ideas and advice about responses to COVID changed, it wasn't because science or scientists had been "wrong." It's that what we thought we knew changed as we learned more. Advice to not use, or use, masks is a good example. We needed to know the size of the droplets and their speed of transit and proximity to an inhaling nose, to predict parameters for infection transmission and hypothesize how we could best respond.


Science isn't a static proof of anything. And it is dynamic.


The public could gain a good understanding of what science is, and is not, by observing the scientific method on display at science fairs.


I've judged science fairs, at all levels, for a long time, through pre-Internet posters done with magic markers and oaktag (whatever that was), to the zoom renditions of the past three years, to a fantastic in-person experience last weekend. Participants display the results of sometimes years-long projects, in posters and powerpoint presentations and demonstrations, that adhere to and elaborate on the steps of the scientific method. Sophistication of projects has paralleled the growth of information science, including wide availability of data ripe for comparison, interpretation, and further hypothesizing.


To continue reading, go to DNA Science, where this post first appeared.

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COVID Virus Ventures Beyond the Lungs, Often Lodging in the Brain

COVID inflames blood vessel linings in the brain, but the virus also enters brain cells (NIH).


In early 2020, COVID appeared to be mostly respiratory, with blame for the shattering of delicate lung tissues initially placed on the violent "cytokine storms" unleashed from overactive immune responses. At first, autopsy series focused on the inflammation and antibodies, not finding evidence of the virus itself. But that view has changed.


As the fourth year of the pandemic dawns, a study published in Nature from Daniel Chertow, MD, MPH, head of the Emerging Pathogens Section at the NIH Clinical Center and colleagues, finds the virus in many body parts – particularly, the brain. The discovery may explain cases of long COVID.


Indirect Attack on the Brain


At first, researchers thought the role of the virus on the brain was indirect.


In July 2022, Avindra Nath, MD, clinical director of the National Institute of Neurological Disorders and Stroke and colleagues reported in the journal Brain changes in the brains of nine people who died quickly from COVID. Autopsies revealed antibodies glommed onto viral antigens on the tile-like endothelial cells that form the blood-brain barrier. As capillaries disintegrated, the risk of stroke skyrocketed amid catastrophic destruction.


The COVID-infected brain is a mess.


To continue reading go to DNA Science, where this post first appeared.


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Yet Another Reason to Not Eat Beef: Cancer-Causing Mutations

I stopped eating beef 5 years ago, following a trip to Costa Rica just days after being diagnosed with breast cancer. Our daughter had been urging us to give up red meat for more than a decade, but a lecture and slide show on the effect of cattle ranching on Costa Rica's spectacular biodiversity, right after my diagnosis, finally did the trick. So compelling were the environmental and human health reasons to no longer eat beef that I barely dwelled on the obvious animal cruelty aspect.


Back home, I wrote about another anti-beef argument here at DNA Science: a sugar (a type of sialic acid) on our cell surfaces that is slightly different than versions on muscle cells of cattle and pigs. The cells of these animals make an enzyme that dismantles their form of sialic acid, but our cells don't. As a result, the human immune system reacts to cow and pig muscle cells bearing sialic acid with its inflammatory response. Over time, thanks to hamburgers and steaks and ribs, risks of cardiovascular disease, arthritis, and cancer rise.


A few days ago, my husband and I returned from a second trip to Costa Rica. This time, we saw firsthand the stark difference between cattle grazing land and the plants-upon-plants-upon-plants that make up natural ecosystems.


To continue reading, go to DNA Science, where this post first appeared.

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Do Shrinking Chromosomes Put Older People at Higher Risk of Severe COVID?

When a headline in the Washington Post dubbed COVID "A Plague of the Elderly," I cringed, envisioning Logan's Run, the sci-fi classic in which people past a certain age voluntarily die. The film came out in 1976, the year I graduated college.


That would make me, well, elderly.


Yes, older folks are over-represented among those who get very sick or die from COVID, with "nearly 9 out of 10 deaths now in people 65 or older," WaPo reminds us. That is striking for an age group that makes up only 16 percent of the population. But while media reports trumpet the damning statistics, few delve into the biology behind the elevated risk: it could be that our shorter chromosomes hamper the immune response.


The WaPo article, like others, states the obvious:

"The vulnerability of older people to viruses is neither surprising nor new. The more we age, the more we accumulate scars from previous illness and chronic conditions that put us at higher risk of severe illness."


Yes, a 75-year-old with COPD is less likely to survive COVID pneumonia than a 75-year-old with healthy lungs. And developing COPD is more likely after decades of exposure to irritants. But number of years by itself may be a surrogate for some other factor.

Might the culprit be telomeres, the tips of chromosomes? They shrink as time passes, like candles burning down.


To continue reading, go to DNA Science, where this post first appeared.

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On the Third Anniversary of the Pandemic, My 100th COVID Article, With Links to All

Three years ago, health officials in China announced the first cases of infection with a "novel coronavirus."


Dr. Zhang Jixian reported the first case on December 26, 2019 in a senior couple living in the residential community near her hospital in Wuhan. An expert in SARS, she recognized the triad of fever, cough, and an unusual pneumonia.


The earliest events remain a bit murky.


"On December 30th, China reported an outbreak of respiratory disease in Wuhan City, a major transportation hub about 700 miles south of Beijing with a population of more than 11 million people," declared Nancy Messonnier, director of CDC's National Center for Immunization and Respiratory Diseases, on January 17, 2020.


But I heard about it on NPR shortly after New Years.


My first COVID post was January 23: "I'm astonished at the speed with which geneticists and epidemiologists are zeroing in on the Wuhan coronavirus," referring to the first viral genome sequence announced January 15. Sequencing viral genomes would evolve into a powerful tool of, well, viral evolution, with the US caught behind.


It's been a hellish roller coaster ride, with terrible tragedy juxtaposed against some of the most astonishingly brilliant science I've ever encountered. I switched from covering rare genetic disease to following the erupting pandemic, reporting news, interpreting technical reports, and delving into the history of epidemiology.


To continue reading, go to DNA Science, where this post first appeared.

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