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Genetic Linkage

SARS-CoV-2 Pops Up, Mutated, Beyond the Respiratory Tract

As if the waves of novel variants of "interest" and "concern" sweeping the planet haven't been enough, and we find versions of SARS-CoV-2 dodging in and out of species in a complex pattern of spillovers and spillbacks, we discover that it's even sneakier. Two new papers in Nature Communications, from a group at the Max Planck Bristol Centre of Minimal Biology, describe how the virus can differ genetically in different parts of the same host.


That may mean that if vaccines and treatments vanquish the virus in the respiratory tract, the pathogen might persist elsewhere. And the viruses in new places replicate and infect more vigorously, better able to elude our immune response. That's not good news as protection from vaccinations or having had COVID-19 wanes.


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

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Rare Disease Day 2022: Juvenile Huntington’s Disease

In honor of Rare Disease Day 2022, February 28th, I'm reposting a DNA Science story from nine years ago. February 16th was 12 years since Jane Mervar lost her young daughter to Huntington's disease (HD). Thank you

Jane for always sharing your story! (Updates are in parentheses.)


Looking back, signs that Jane Mervar's husband, Karl, had HD started when their youngest daughter, Karli, began to have trouble paying attention in school. Karl had become abusive, paranoid, and unemployable due to his drunken appearance. Karli, born in September 1996, was hyperactive and had difficulty following directions.


When by age 5 Karli's left side occasionally stiffened and her movements slowed, Jane began the diagnostic journey that would end with Karli's diagnosis of HD, which had affected her paternal grandmother.


Soon Karli could no longer skip, hop, or jump. New troubles emerged. "She had cold sweats, tachycardia, and chronic itching. She fell and suffered chronic pain. By age 6 she was losing her speech and became withdrawn," Jane recalls. Karli drooled and her speech became unintelligible. By age 7 her weight had plunged, and by age 8 she had developed pneumonia three times, due to difficulty swallowing. By age 9 she required a feeding tube, suffered seizures, and would go long periods without sleep.


An Adult's Disease in a Child


This isn't the way that a disease is supposed to run in families, striking child before parent. HD is regarded as a disease of adulthood, but in fact about 10 percent of people with the condition are under age 20 – they have juvenile Huntington's disease (JHD).


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

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Converting Donor Lungs to Universal Blood Type O Could Boost Organ Supply

Lung transplants can be lifesaving for patients with end-stage lung diseases such as cystic fibrosis, COPD, pulmonary fibrosis, sarcoidosis, and pulmonary hypertension. Wait times for a lung vary from days to years, depending on a complex set of circumstances. In the US, 1400 adults and children await lungs at any given time. Less than a third of them will get one.


Position on the wait list is based on several factors: medical urgency, compatibility with an available lung, distance from the donor hospital, and pediatric status, according to the United Network for Organ Sharing.


An easily tested indication of whether a person's body will accept a transplanted organ is the ABO blood type. It doesn't have to match between donor and recipient, but it must be compatible. The A and B antigens (cell surface molecules) are sugars that are attached to proteins and fats on a cell's surface. The blood type is a single-gene trait.


Canadian researchers have tested a way to strip donor lungs from type A individuals of the A antigens that make them type A, using enzymes. Denuding the lungs essentially creates an "ABO-agnostic organ" that could, theoretically for now, nestle into the chest of a person with any ABO blood type and not induce rejection. The idea has been around for awhile without much success, but using a new pair of enzymes, discovered in the human gut microbiome in 2019, seems to improve on past attempts. 


"The treatment described here could further expand the pool of universal donor organs from the current 55% (blood group O donors) to over 80%. This strategy may greatly improve access and fairness of organ allocation," Aizhou Wang and colleagues from the University of Alberta write in Science Translational Medicine. The strategy could be applied to organs other than lungs. More than 100,000 individuals in the US await organs.


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


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