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Genetic Linkage

How a Mutation Turned Almonds from Toxin to Treat

Eating just 50 bitter almonds can release enough hydrogen cyanide to kill an adult in under 3 minutes. Fortunately, the sweet variety that we scoop from bins at grocery stores is safe to eat, thanks to a mutation.

 

While the single-gene glitch behind almond palatability has been recognized for a century, it took genome sequencing to reveal the complex control of the trait. Raquel Sánchez-Pérez, a biochemist at CEBAS-CSIC, an agricultural research center in Spain, and colleagues at the University of Copenhagen and elsewhere in Europe, published their findings in Science in June.

 

A Beloved Nut Through History

 

Almonds lead pistachios, brazil nuts, walnuts, pecans, cashews, and pine nuts in tree nut popularity, with peanuts the most popular groundnut.


In 2016 Michelle Obama joked that her husband consumes exactly 7 almonds every night. "That's it!" she exclaimed. When The New York Times reported the observation seriously, eating 7 almonds became a thing.

 

Headlines shout the attributes. "9 Evidence-Based Health Benefits of Almonds" lists vitamins, minerals, and anti-oxidants, crediting the nuts with lowering blood sugar, cholesterol, and hunger. So many articles tout the ability of almonds to "melt away body fat" that, well, it must be true.

 

To continue reading go to my DNA Science blog at Public Library of Science, where this post first appeared. 

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Beaver Feces Inspire a Way to Convert Type A to Type O Human Blood

My writing assignments for Medscape Medical News tend to be formulaic: summarize the findings of an interesting new paper, enabling busy health care professionals to stay on top of the literature. I knew immediately the importance of an assignment from a few weeks ago – a team from the University of British Columbia had found a way to convert type A blood to type O. The report, in Nature Microbiology, details how they commandeered a pair of enzymes from a human gut bacterium.

 

That's huge.

 

Type O blood is the "universal donor." An individual of any ABO blood type can receive it without suffering a rejection reaction, until supplies of the matched type become available. That's because the surfaces of red blood cells (RBCs) that are type O lack certain glycoprotein molecules that festoon cells of types A, B, or AB.

 

Because more people have type O blood (45%), finding a way to make more of it could help address the ongoing shortage of human blood. The American Red Cross recently began offering gift cards to entice type O donors, warning that unless supplies extend from 2-days to 5-days, some emergency departments will be without blood and some types of surgeries delayed.

 

I guessed that the researchers had found some way to denude types A, B, or AB RBCs – shake them, zap them, bathe them in enzymes – but I didn't imagine that beaver dams would be an inspiration. My Medscape article had only a sentence on the beaver connection, so I thought I'd elaborate here at DNA Science, where inquiring minds gravitate to the weird.

 

 

To continue reading, go to my blog DNA Science, at Public Library of Science.

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How microbiome research promises to solve blood shortages, halt food allergies and give us better skin

Is your body wash gentle on your microbiome? asks the voiceover in a Dove ad.

 

A half dozen befuddled young women then attempt the Herculean task of repeating the word "microbiome." Finally, one says, "I actually don't even know what that is!"

 

MotherDirt Body Wash has "been screened and tested using our biome-friendly platform for compatibility with the skin's natural biome," reads the label. Sounds good! But a closer look reveals it's liquid soap with a pinch of salt, a dash of sweet almond oil, citric acid, and, of course (?), some hydrolyzed pea protein.

 

Popularity of "microbiome"-as-buzzword must have presented an advertising challenge for a body wash, which must remove dirt but not unsettle the microbial residents of the human epidermis. And so the products promise to maintain the skin microbiome, as if it's going to spontaneously evaporate unless one forks over $30 for a bottle of soap.

 

To continue reading, go to Genetic Literacy Project, where this post first appeared. 

 

 

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Pot smokers with this genetic variant could face addiction risks similar to those who smoke cigarettes

Back in the 1960s and 1970s, for those of us who can remember them, marijuana was widely regarded as not being addictive, compared to other drugs and of course to cigarettes. We smoked often just because we liked it and it was part of our social structure. But there may have been more to it.

 

Today, with decriminalization of cannabis spreading across the country, researchers are trying to learn more about the ways our brains are affected by the plant. And one of the things we're finding is that pot may be more addictive than we thought.  A recent study in Nature Neuroscience suggests that for people with a certain genetic variant, pot may be addictive in much the same way as cigarettes.

 

To continue reading go to Genetic Literacy Project, where this post first appeared.

 

 

 

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Did you get a DNA ancestry kit for Father’s Day? Here are some things to consider before spitting in that vial

Ads for DNA testing kits on social media and TV seem to usher in every holiday. The pitches for Father's Day dropped right after Mother's Day:

 

$50 off at 23andMe, plus free gift wrap! Offer ends June 17.

 

"Celebrate Dad's Genes" Father's Day Sale with 25 percent off at Family Tree DNA," offer also expiring June 17.

 

"Give the world's greatest Dad our best DNA experience yet. $40 off!" shouts AncestryDNA. "Now with greater details and new features, Dad can get a richer view of his story and discover what he's made of. Give Dad the Gift of Discovery!"

 

 

If my father were alive to open an enticing shiny package and "discover what he's made of" by sending in a spit sample, he'd find that it's not what I am made of. He'd discover that, biologically speaking, he isn't my father at all. But he raised me, so of course he was.

 

To continue reading, go to Genetic Literacy Project, where this post first appeared.

 

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Do China’s controversial CRISPR babies illustrate the need for an ‘undo button’?

The editing of the genomes of twin girls announced via YouTube in November 2018 using CRISPR/Cas9 set off alarm bells for the premature use of the controversial technology. But the protests may have been misplaced: it wasn't just the germline gene editing, but choice of the delivered gene – CCR5 – that might introduce risk. A new report in Nature Medicine indicates that the engineered mutation is associated with increased mortality.

 

 

To continue reading go to Genetic Literacy Project, where this post first appeared.

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When a Rare Mutation Causes a Rare Disease: Jacob’s Story

For some parents, a physician's advice to "just take him home and love him," presumably letting nature take it's most likely course, is just not acceptable. This blog has championed many such parents, who serve as catalysts for others.

 

New to rare disease territory is Orah Lasko, whose toddler Jacob not only has an exceedingly rare disease, but a highly unusual mutation behind it. With all of the media coverage of the high costs of new biotech-based treatments – gene therapy, targeted cancer drugs, monoclonal antibody-based drugs, antisense oligonucleotides – having such a double dose of rarity could be quite an obstacle.

 

But that's not stopping Orah. Nor are the words of a neurologist who advised her to stop pursuing treatments.

 

The Diagnostic Odyssey

 

Orah Lasko's pregnancy, her third, had been uneventful, with normal findings on the standard prenatal tests. Jacob seemed okay when he was born in September 2017, with minor feeding issues that went away. His small genitals didn't set off any alarm bells.

 

But as the months went on, other things appeared. Or didn't.

 

 

To continue reading, go to my blog, DNA Science.

 

 

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DNA for the greater good: Should the police have access to consumer DNA databases?

 In the spring of 2018, the capture of the Golden State Killer using a consumer DNA database catapulted the issue of genetic privacy into the headlines. A year later, a second case has pushed genetic privacy to the precipice of a slippery slope as the mothership of DNA databases involved in both cases, GEDmatch, has changed its Terms of Service to give users more control over accessibility of their data to law enforcement.

 

But will increased privacy control slow the momentum in using DNA to catch criminals? The new forensic technology is cracking a case a week now, turning cold cases red hot.

 

The FBI works with genetic genealogists at Parabon NanoLabs, which for many cases uses GEDmatch, which is free. These experts combine DNA information with traditional resources like historical accounts, diaries, and census data to identify individuals.

 

The Utah case

 

This spring's flashpoint centered on use of GEDmatch to break an assault case in Utah. Up until then, the 55 crimes that Parabon Nanolabs had solved using DNA data had all been sexual assault or murder.

 

To continue reading, go to Genetic Literacy Project, where this post first appeared.

 

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Revising Textbook Coverage of Prenatal Diagnosis in an Anti-choice Climate

I've become a stalker.

 

When I recently stopped at an intersection behind a car with bumper stickers "Make Abortion Criminal Again" and "Worship GOD, not GOV," I followed the offensive vehicle into the parking lot of Target. Out emerged an older white man who took no notice of me approaching, phone camera out.

 

I'm willing to bet that he never had to carry to term, in his body, a fetus known to have a severe chromosomal anomaly.

 

I'd bet that he was never forced to remain pregnant, give birth, and then watch the newborn die.

 

Yet the man in the Target lot, if those bumper stickers were indeed his, feels empowered to take the choice to abort this tragedy from women he doesn't know.

 

But I thank him for the lead-in to this blog post.

 

What's To Become of Prenatal Diagnosis?

 

I'm revising my human genetics textbook for a 13th edition, and I've hit a roadblock at this sentence:

 

"If a test reveals that a fetus has a serious medical condition, the genetic counselor discusses possible outcomes, treatment plans, and the option of ending the pregnancy."

 

I describe those prenatal tests in depth earlier, focusing on how testing fetal DNA in a woman's circulation is replacing the riskier amniocentesis and CVS. But I now have to add "possible" before "option."

 

To continue reading, go to my DNA Science blog at Public Library of Science, where this post first appeared.

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Clinical Trial Set to Start for CLN1 Batten Disease

On May 21, Abeona Therapeutics announced the go-ahead from the Food and Drug Administration (FDA) for a clinical trial to test a gene therapy for a form of Batten disease called CLN1 disease, aka infantile neuronal ceroid lipofuscinosis. The King family and their organization Taylor's Tale has supported the research that made the clinical trial possible since their beloved Taylor was diagnosed at age 7 in 2006.

 

The eight forms of Batten disease are ultrarare – together they account for only 1 in 100,000 individuals. Each is caused by mutation in a different gene, but all cause neurodegeneration. The conditions were originally named for what was thought to be the typical age of onset, before much was known about the genetics or the natural histories. CLN1 is now recognized to manifest in infancy, late infancy, and in children (juvenile), and Taylor had the juvenile form.

 

CLN1 is the classic "infantile" form. But Taylor King was no longer an infant when she experienced the first subtle sign, a new difficulty with numbers in the first grade. Taylor had taught herself to read at age three.

 

"There were signs of the secret hiding in Taylor's genes even then, but they were too complex and too twisted for any of us to understand," wrote her sister Laura in her book Run to the Light, which I reviewed here.

 

To continue reading, go to my DNA Science blog for Public Library of Science, where this post first appeared.

 

 

 

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