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Alexander Gardner via Wikimedia Commons // Public Domain

Did Abraham Lincoln Have a Genetic Mutation?

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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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Food
Researchers Pinpoint the Genes Behind the Durian's Foul Stench
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Durian is a popular fruit in parts of southeast Asia. It's also known for having the most putrid, off-putting odor of any item sold in the produce section. Even fans of durian know why the fruit gets a bad rap, but what exactly causes its divisive scent is less obvious. Determined to find the answer, a team of researchers funded by "a group of anonymous durian lovers" mapped the fruit's genome, as reported by the BBC.

The study, published in the journal Nature Genetics [PDF], contains data from the first-ever complete genetic mapping of a durian fruit. It confirms that durian's excess stinkiness comes from sulfur, a chemical element whose scent is often compared to that of rotten eggs.

Analysis of the fruit's chemical makeup has been done in the past, so the idea that sulfur is a major contributor to its signature smell is nothing new. What is new is the identification of the specific class of sulfur-producing genes. These genes pump out sulfur at a "turbocharged" rate, which explains why the stench is powerful enough to have durian banned in some public areas. It may seem like the smell is a defense mechanism to ward off predators, but the study authors write that it's meant to have the opposite effect. According to the paper, "it is possible that linking odor and ripening may provide an evolutionary advantage for durian in facilitating fruit dispersal." In other words, the scent attracts hungry primates that help spread the seeds of ripe durian fruits by consuming them.

The revelation opens the door to genetically modified durian that are tweaked to produce less sulfur and therefore have a milder taste and smell. But such a product would likely inspire outrage from the food's passionate fans. While the flavor profile has been compared to rotten garbage and dead animal meat, it's also been praised for its "overtones of hazelnut, apricot, caramelized banana, and egg custard" by those who appreciate its unique character.

[h/t BBC]

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Why DNA Is So Hard to Visualize
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Picture a strand of DNA and the image you see will likely be similar to the artist’s rendering above. The iconic twisted ladder, or double-helix structure, was first revealed in a photo captured by Rosalind Franklin in the 1950s, but this popular visualization only tells part of the story of DNA. In the video below, It’s Okay to Be Smart explains a more accurate way to imagine the blueprints of life.

Even with sophisticated lab equipment, DNA isn’t easy to study. That’s because a strand of the stuff is just 2 nanometers wide, which is smaller than a wavelength of light. Researchers can use electron microscopes to observe the genetic material or x-rays like Rosalind Franklin did, but even these tools paint a flawed picture. The best method scientists have come up with to visualize DNA as it exists inside our cells is computer modeling.

By rendering a 3D image of a genome on a computer, we can see that DNA isn’t just a bunch of free-floating squiggles. Most of the time the strands sit tightly wound in a well-organized web inside the nucleus. These balls of genes are efficient, packing 2 meters of DNA into a space just 10 millionths of a meter across. So if you ever see a giant sculpture inspired by an elegant double-helix structure, imagine it folded into a space smaller than a shoe box to get closer to the truth.

[h/t It’s Okay to Be Smart]

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