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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


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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.


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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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