Alexander Gardner via Wikimedia Commons // Public Domain
Alexander Gardner via Wikimedia Commons // Public Domain

Did Abraham Lincoln Have a Genetic Mutation?

Alexander Gardner via Wikimedia Commons // Public Domain
Alexander Gardner via Wikimedia Commons // Public Domain

Abraham Lincoln's life has provided material for scores of historians. But one aspect of his history is being investigated by a very different kind of expert: geneticists. Lincoln’s appearance and medical history have some convinced that he had a condition called Marfan syndrome.

Marfan syndrome is one of a family of connective tissue disorders—that is, conditions that affect the glue that holds the body together. It affects many body systems and can be quite serious, but its most obvious signs are external: an unusually tall, lanky stature; and long limbs, hands, and feet—and if that doesn’t describe Abraham Lincoln, nothing does. 

The condition affects about 1 in every 5000 people, but because the syndrome is frequently inherited, many of the people who have it are related. And when one person is diagnosed, physicians frequently start looking at that person’s ancestry. Such was the case of a 7-year-old boy diagnosed in 1964. The diagnosing physician, a man named Harold Schwartz, had traced his patient’s family tree back more than 200 years, all the way to Mordecai Lincoln II, Abraham’s great-great-grandfather. 

Two years before Schwartz’s discovery, a doctor named A.M. Gordon developed a similar theory, which he published in the Journal of the American Medical Association. Schwartz added his new evidence to the academic literature, and the debate began in earnest.

Opponents of the theory argued that Lincoln had never shown any other symptoms of the condition. He had no heart problems, no lung issues, no eye trouble, and no overtly loose joints. He was 56 years old when he was assassinated, which would have been a pretty decent lifespan for anyone in those days. (Medicine has made great progress in its investigation of Marfan syndrome since Lincoln’s day. While there is no cure, the syndrome is treatable, and people who have it can expect to lead long, full lives.) And besides, the nay-sayers said, if Lincoln inherited the condition from his paternal great-grandfather, how do we account for his mother's looks?

This artist may have taken the resemblance a little too far. Painting by Lloyd Ostendorf via Wikimedia Commons // Public Domain

By most accounts, Nancy Hanks Lincoln was the spitting image of her son, with long limbs and a sad, melancholic face. A minister who was a friend of the family described her as “quite tall…bony, angular, lean…She had long arms, large head, with the forehead exceedingly broad … with chest sunken.” Nancy died at the age of 34, either from “milk sickness” or “wasting disease,” depending on which records you read. Whether there were other elements involved in her death, we’ll likely never know.

Her son is another story. Scientists discovered the gene associated with the condition in the 1990s, which suggested to them that genetic testing was possible, as long as you had a sample of someone’s DNA.

As it so happens, we’ve got that. Historians have preserved a number of grisly artifacts from the night of Lincoln’s assassination, including locks of hair, skull fragments, and even his blood, which soaked into his surgeon’s shirt sleeves.

Once scientists realized that they could potentially test the former president's DNA, a second question arose: Should they? In the 1990s, the National Museum of Health and Medicine created a committee of geneticists, lawyers, and forensic scientists, and left the decision up to them.

Those in favor of proceeding argued that, as an American hero, Lincoln could be a beacon and an inspiration for people living with the condition today. Addressing the committee, one person with Marfan syndrome said, “The fact that Lincoln may have had Marfan syndrome shows those of us that we too can contribute something of value to society … It’s time that all people, especially medical ethicists, realize that having the Marfan syndrome is not shameful, it’s just darned inconvenient.”

Those against emphasized how private Lincoln was in life, and stressed that to conduct medical tests on him without his consent would be a huge invasion of that privacy.

The committee eventually decided that, had he been alive, Abraham Lincoln would have consented to testing if the results could have helped other people. Unfortunately, their decision was moot. Additional Marfan-related genes had been discovered during their deliberations, and a definitive diagnosis would not really be possible.

Did Abe Lincoln have Marfan syndrome? We still don’t know for sure. But even without an answer, the debate about Abraham Lincoln’s appearance continues to raise public awareness of a condition affecting thousands of Americans.

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Banana Panic! Is the Fruit Really on the Brink of Extinction?
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Enjoy your banana pancakes while they last. A tropical fungus that causes Panama disease could wipe out the Cavendish—the most popular variety of banana—in the not-so-distant future. To make matters worse, a wild crop of bananas in Madagascar that could help diversify the fruit's gene pool and protect the Cavendish was just put on the extinction list, the BBC reports.

Throughout the world, the Cavendish is the type of banana that’s most commonly consumed. The Madagascan banana produces seeds, rendering it inedible, but researchers at the Kew Madagascar Conservation Centre say it could be cross-bred to create a new kind of banana that’s both tasty and resilient. In other words, the key to saving the fruit is expanding its genes. Although it is nearly extinct, the African variety seems particularly promising because it could have unique properties that make it resistant to drought or disease.

"It doesn't have Panama disease in it, so perhaps it has genetic traits against the disease," Richard Allen, senior conservation assessor at the Royal Botanic Gardens, Kew, told the BBC. "We don't know until we actually do research on the banana itself, but we can't do the research until it's saved."

Banana panic has been ongoing for a few years, but Snopes reports that some fears—like claims that bananas will be extinct within a decade—are unfounded. However, threats to the Cavendish banana are very real, and it’s not the only crop that’s vulnerable. The world’s most popular wine grapes are also susceptible to pandemics for similar reasons, including a lack of genetic diversity. Scientists are now crossbreeding different varieties of grapes—much like efforts to save the banana—in an effort to keep the wine flowing.

[h/t BBC]

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Why the World's Most Popular Wine Grapes Are Vulnerable to a Pandemic
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When you're in the wine shop looking for the right wine to pair with your meal or bring to the party, the variety on the shelves seems rich and diverse, their taste influenced by the grape, soil, climate, and age. Among the most famous are the French "noble wines"—cabernet sauvignon, merlot, pinot noir, chardonnay, riesling, and sauvignon blanc—so called for being associated with high quality and easy growth in a variety of places.

But it turns out that many of the most famous grapes in the world are like nobility in another way: They're as inbred as a royal family, and have been for hundreds—and in some cases thousands—of years.

"Scientists are getting really concerned that this is setting up the perfect scenario for a great pandemic," Kevin Begos, whose new book, Tasting the Past, explores the history, archaeology, genetics, and future of wine, said at a recent book release event in New York City. They fear that a single merciless pathogen could wipe out many grapes around the world in the same way that a single fungus, Phytophthora infestans, eradicated the variety of potato common across Ireland in the 1840s, causing the great famine.

The vast majority of wine produced across the world derives from a single grapevine species: Vitis venifera. The domesticated grape has thousands of varieties, and quite a lot of genetic diversity among them, according to a 2010 paper in PNAS that analyzed genome-wide genetic variation of more than 1000 samples of V. vinifera subsp. vinifera and its wild relative, V. vinifera subsp. sylvestris. But that's not true for all grapes: Nearly 75 percent of cultivars had a first-degree relationship to at least one other. They were either parents or children.

The most popular commercial wines are made from a handful of these inbred grapes. Sauvignon blanc, for instance, has a first-degree relationship with cabernet sauvignon, cabernet franc, and chenin blanc, among many others. That genetically cozy family isn't unusual. You see it all over the grapevine.

Another problem is how grapes reproduce in vineyards. Instead of pollinating these hermaphroditic plants or growing them from seeds, as might happen naturally, grape growers generally make new plants from cuttings of existing ones, essentially cloning the same vines over and over.

They use this method to produce consistent flavor quality—and it's nice to decant a bottle of your favorite wine and know what to expect with the first sip. But this practice has kept some popular grapes in relative genetic stasis for a long time. Take pinot, parent of chardonnay and gamay, which has been cloned for 2000 years. Genetically, it's remained virtually unchanged—but the organisms that prey on it have not. "All those insects and pathogens and mildews that attack grape vines have been evolving," Begos said. "And they always figure out new ways to attack the grape vines."

Despite the wide use of pesticides—in the last 10 years, 260 million pounds of pesticides were put on wine grapes in California alone—"the industry is losing the arms race to the pathogens," Sean Myles, an author of the 2010 PNAS grape genome study, told Begos in Tasting the Past. "It’s really only a matter of time. If we just keep using the same genetic material, we’re doomed.”

The good news is that grape diversity could be the key to preventing rosé season from disappearing. Scientists are looking outside the noble wines and their popular cousins to old, wild, and lesser-known varieties, which "turn out to have natural disease resistance, and they've kept evolving," Begos said.

The idea is create hybrids selected for specific traits—not just pest resistance, but an ability to withstand greater heat in an era of climate change, adaptability to a wider variety of soils, and other resilient qualities.

One effort is VitisGen, a USDA-funded project involving researchers from a handful of American universities, including UC Davis, Cornell University, and the University of Minnesota. By studying the genomes of a variety of grapes, they're creating an enormous database of genetic traits. They're also experimenting with crossbreeding. Some of this genetic tweaking is decidedly old school, including pollinating grapes by hand.

Begos tells Mental Floss that they're especially interested in developing grapes that are resistant to downy mildew (Plasmopara viticola), a potential plague a la the potato famine. It can cause total crop loss if not controlled.

When it comes to selecting traits, it probably won't be flavor they'll be pulling from wild grapes, which "are really kind of terrible," Begos said. (In Tasting the Past, he quotes wine experts who describe the flavor of a fox grape as combining "animal fur and candied fruits.”) It's generally hardiness they're looking for. The concord grape in your kid's PB&J, for example, is "really tough," Begos said. Select some of its hardy genes and cross them with, say, the peppery flavor genes of the syrah grape—which the researchers have also identified—and maybe you can create a genetically resilient hybrid.

"The University of Minnesota has already had success identifying cold-hardy wine grape genes, and breeding them into new varieties that have impressed the toughest critics," Begos says, pointing to a 2015 top 10 wine list from New York Times food critic Eric Asimov. Number two on the list was made from hybrid grapes developed by UM.

You can do your part to encourage wine diversity by getting adventurous with your vino, trying a grape you've never heard of or blends from new regions. Check out organic and small wineries, which are experimenting with old cultivars and new varieties. And don't be afraid of a future with genetically tweaked grapes. We've been modifying them as long as we've been growing them. As Begos writes of these efforts, "At heart they’re unlocking flavor, disease-resistance, and growth genes that may be tens of millions of years old. To me these scientists are doing exactly what ancient Babylonians, Egyptians, and Greeks did: refining wine grapes to produce tastes we enjoy."

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