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    Francisco Lopera, the ‘Country Doctor’ Who Upended Our Understanding of Dementia

    Francisco Lopera defied rebels, cartels and vampire bats to become a pioneering researcher of Alzheimer’s disease.In 1978, Dr. Francisco Lopera did what recent medical school graduates in Colombia and much of Latin America have long done: He set out for an obligatory year of work in a remote part of the country, where an inexperienced médico rural might be the only physician for miles. Dr. Lopera, who was born in the Andean region of Antioquia and knew mostly mountains and farm life before medical school, carried out his service in the Darién Gap, on the Caribbean coast near Panama.There Dr. Lopera, a groundbreaking Colombian Alzheimer’s researcher who died this week at age 73, treated stabbings, snakebites, complicated births, burns and fevers in a hospital that had electricity for only half the day. On one occasion, he was kidnapped by Marxist guerrillas. Another time, he had to flee gunshots.When I met Dr. Lopera in 2017, to start research on a book about the families with Alzheimer’s that became his life’s work, he told me a story about two young brothers who had died one after the other in his hospital, of unknown causes. Lopera traveled to the family home in a remote jungle clearing, where he discovered that the boys’ surviving siblings had bites on their fingers from vampire bats. He sent the bodies to a pathology lab hours away by boat, and the pathologists confirmed rabies. When the government brought in a rabies expert to investigate, Dr. Lopera joined him.He left that experience — long nights in the rainforest, searching for hidden roosts, engrossed in the natural history of rabies and bats — wanting to become a rabies epidemiologist. But that was not to be. His interests were eclectic and quick to change, and a few years later he became a neurology resident in Medellín.In 1984, Dr. Lopera examined a farmer in his 40s who appeared to have dementia. Dr. Lopera took again the unusual step of traveling to the family home, in a mountain hamlet like the one where he had been born. Not just the farmer had symptoms of dementia, he saw — a brother also appeared to be affected. Dr. Lopera had discovered what would turn out to be the world’s largest family with early-onset Alzheimer’s disease. The family shared a genetic mutation, later nicknamed the paisa mutation, that was unique to their region of Colombia. Dr. Lopera spent the next four decades studying the family’s 6,000 members.Dr. Francisco Lopera, second from right, in Yarumal, Colombia, in 2010, with Oderis Villegas, center, who was showing signs of Alzheimer’s disease at age 50. A sister, María Elsy, left, had a more advanced case.Todd Heisler/The New York TimesWe are having trouble retrieving the article content.Please enable JavaScript in your browser settings.Thank you for your patience while we verify access. If you are in Reader mode please exit and log into your Times account, or subscribe for all of The Times.Thank you for your patience while we verify access.Already a subscriber? Log in.Want all of The Times? Subscribe. More

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    A Mammoth DNA Discovery Helps Map an Ancient Genome in 3-D

    In 2018 an international team of scientists — from labs in Houston, Copenhagen, Barcelona and beyond — got their hands on a remarkable biological specimen: a skin sample from a 52,000-year-old woolly mammoth that had been recovered from the permafrost in Siberia. They probed the sample with an innovative experimental technique that revealed the three-dimensional architecture of the mammoth’s genome. The resulting paper was published on Thursday in the journal Cell.Hendrik Poinar, an evolutionary geneticist at McMaster University in Canada, was “floored” — the technique had successfully captured the original geometry of long stretches of DNA, a feat never before accomplished with an ancient DNA sample. “It’s absolutely beautiful,” said Dr. Poinar, who reviewed the paper for the journal.The typical method for extracting ancient DNA from fossils, Dr. Poinar said, is still “kind of cave man.” It produces short fragments of code composed of a four-letter molecular alphabet: A (adenine), G (guanine), C (cytosine), T (thymine). An organism’s full genome resides in cell nuclei, in long, unfragmented DNA strands called chromosomes. And, vitally, the genome is three-dimensional; as it dynamically folds with fractal complexity, its looping points of contact help dictate gene activity.“To have the actual architectural structure of the genome, which suggests gene expression patterns, that’s a whole other level,” Dr. Poinar said.“It’s a new kind of fossil, a fossil chromosome,” said Erez Lieberman Aiden, a team member who is an applied mathematician, a biophysicist and a geneticist and directs the Center for Genome Architecture at Baylor College of Medicine in Houston. Technically, he noted, it is a non-mineralized fossil, or subfossil, since it has not turned to stone.Erez Lieberman Aiden, director of the Center for Genome Architecture at Baylor College of Medicine in Houston.Brandon Thibodeaux for The New York TimesThe trunk of a 39,000-year-old woolly mammoth nicknamed Yuka that also yielded fossil chromosomes in the study.Love Dalén/Stockholm UniversityWe are having trouble retrieving the article content.Please enable JavaScript in your browser settings.Thank you for your patience while we verify access. If you are in Reader mode please exit and log into your Times account, or subscribe for all of The Times.Thank you for your patience while we verify access.Already a subscriber? Log in.Want all of The Times? Subscribe. More

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    Alexi Pappas: You Can’t Run From Your Fears Forever

    You can try your hardest to run away from your fears, but you can’t hide from them forever.This essay is part of a series called The Big Ideas, in which writers respond to a single question: What do we fear? You can read more by visiting The Big Ideas series page.“Your mommy was just so sad that she had to go.”I’ve been told this all my life. I suppose that this framing is meant to comfort me, as if my mom’s suicide was as natural, unavoidable and unfortunate as a sand castle facing its eventual collapse. I have never found this explanation reassuring, though, because she contributed to half of my DNA. I have no control over how much of my mom’s mental illness is inside of me. If her suicide was inevitable, would I face the same outcome as her? Would I one day “have to go,” too?My mom had bipolar disorder with manic depression. After developing an addiction to pain pills that were originally prescribed to treat a back injury due to pregnancy complications, she became suicidal and died in 1994, when I was 4 years old. But before she passed, she was an accomplished athlete and singer, class valedictorian and one of the first female software consultants at her company. Explain to me how, apart from genes, my mom could have so many successes … and still “have to go”? Especially since my mom’s only brother “had to go” several years later, too. Two of my own flesh and blood. They both simply “had to go”!So to say that I fear my genes is an understatement. It’s scary to be afraid of the negative traits you may have inherited. It makes you afraid of yourself. And for the longest time, the only way I could think of to avoid my mom’s fate was to rely on another, more undeniably positive aspect of my genetic makeup — my athletic ability.A researcher extracts DNA fragments at the Neurobiology lab Columbia University in Manhattan. Scientists have found that a combination of environmental and genetic factors can contribute to psychiatric illnesses.Jeenah Moon for The New York TimesIn addition to a predisposition toward mental illness, I also inherited an undeniable athletic talent: the ability to run long distances. So, I concentrated my efforts on becoming an Olympian. Because forever an Olympian, forever happy, right?We are having trouble retrieving the article content.Please enable JavaScript in your browser settings.Thank you for your patience while we verify access. If you are in Reader mode please exit and log into your Times account, or subscribe for all of The Times.Thank you for your patience while we verify access.Already a subscriber? Log in.Want all of The Times? Subscribe. More

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    Ancient Maya Genomes Sequenced for First Time

    Thousand-year-old DNA from Chichén Itzá offers eye-opening details of the religious rituals of ancient Maya.In the spring of 1967, workers building a small airport behind Chichén Itzá, the ancient Maya city in Mexico, ran into a problem: Their excavations had uncovered human remains in the pathway of the proposed runway. The airport was set to serve V.I.P.s who wanted to visit Chichén Itzá. But with the remains so close to a major archaeological site, the work had to be halted until the bones could be examined.Any hope for a quick resolution dissolved when archaeologists who were called to the scene uncovered a chultún — an underground rainwater-storage container that, in Maya mythology, was viewed as an entrance to the subterranean land of the dead. Connected to the cistern was a cave containing more than 100 sets of human remains, almost all belonging to children. In a push to finish the airport, researchers were given just two months to excavate and exhume the cache of bones.Nearly 60 years later, ancient DNA extracted from 64 of the children is offering new insights into the religious rituals of the ancient Maya and their ties to modern descendants. In a paper published on Wednesday in the journal Nature, an international cohort of researchers revealed that the children — sacrificial victims killed between 500 and 900 A.D. — were all local Maya boys that may have been specifically selected to be killed in sibling pairs.“These are the first ancient Maya genomes to be published,” said Johannes Krause, an archaeogeneticist at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. The DNA work provided a previously unseen glimpse into the identities of the sacrificed children. “One feels quite moved by such a finding,” Dr. Krause said, noting that he himself has a young son.The search into the genome of the Maya boys did not start as an exercise in ancient Maya rituals. In the mid-2000s, Rodrigo Barquera — now an immunogeneticist at the Max Planck Institute — was hoping to discover the genetic legacy of Mesoamerica’s deadliest pandemic.In 1545, an outbreak of Salmonella enterica spread like wildfire across what is now Mexico. Over the next century, the disease killed up to 90 percent of the Indigenous population. Pandemics like these often leave their mark on the immune genes of survivors. To uncover this genetic legacy, Dr. Barquera and his colleagues needed to compare the DNA from the precolonial remains with that of people who were born after the calamity.We are having trouble retrieving the article content.Please enable JavaScript in your browser settings.Thank you for your patience while we verify access. If you are in Reader mode please exit and log into your Times account, or subscribe for all of The Times.Thank you for your patience while we verify access.Already a subscriber? Log in.Want all of The Times? Subscribe. More

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    Patient Dies Weeks After Kidney Transplant From Genetically Modified Pig

    Richard Slayman received the historic procedure in March. The hospital said it had “no indication” his death was related to the transplant.Richard “Rick” Slayman, who made history at age 62 as the first person to receive a kidney from a genetically modified pig, has died about two months after the procedure.Massachusetts General Hospital, where Mr. Slayman had the operation, said in a statement on Saturday that its transplant team was “deeply saddened” at his death. The hospital said it had “no indication that it was the result of his recent transplant.”Mr. Slayman, who was Black, had end-stage kidney disease, a condition that affects more than 800,000 people in the United States, according to the federal government, with disproportionately higher rates among Black people.Surgeons performing the world’s first kidney transplant from a genetically modified pig into a living human in March.Michelle Rose/Massachusetts General Hospital, via Agence France-Presse — Getty ImagesThere are far too few kidneys available for donation. Nearly 90,000 people are on the national waiting list for a kidney.Mr. Slayman, a supervisor for the state transportation department from Weymouth, Mass., had received a human kidney in 2018. When it began to fail in 2023 and he developed congestive heart failure, his doctors suggested he try one from a modified pig.“I saw it not only as a way to help me, but a way to provide hope for the thousands of people who need a transplant to survive,” he said in a hospital news release in March.His surgery, which lasted four hours, was a medical milestone. For decades, proponents of so-called xenotransplantation have proposed replacing ailing human organs with those from animals. The main problem with the approach is the human immune system, which rejects animal tissue as foreign, often leading to serious complications.Recent advances in genetic engineering have allowed researchers to tweak the genes of the animal organs to make them more compatible with their recipients.The pig kidney that was transplanted into Mr. Slayman was engineered by eGenesis, a biotech company based in Cambridge, Mass. Scientists there removed three genes and added seven others to improve compatibility. The company also inactivated retroviruses that pigs carry and could be harmful to humans.“Mr. Slayman was a true pioneer,” eGenesis said in a statement on social media on Saturday. “His courage has helped to forge a path forward for current and future patients suffering from kidney failure.”Mr. Slayman was discharged from the hospital two weeks after his surgery, with “one of the cleanest bills of health I’ve had in a long time,” he said at the time.In a statement published by the hospital, Mr. Slayman’s family said he was kind, quick-witted and “fiercely dedicated to his family, friends and co-workers.” They said they had taken great comfort in knowing that his case had inspired so many people.“Millions of people worldwide have come to know Rick’s story,” they said in the statement. “We felt — and still feel — comforted by the optimism he provided patients desperately waiting for a transplant.” More

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    What Makes Tiny ‘Water Bears’ So Tough? They Quickly Fix Broken DNA.

    New research finds that microscopic tardigrades are remarkably good at repairing their DNA after a huge blast of radiation.To introduce her children to the hidden marvels of the animal kingdom a few years ago, Anne De Cian stepped into her garden in Paris. Dr. De Cian, a molecular biologist, gathered bits of moss, then came back inside to soak them in water and place them under a microscope. Her children gazed into the eyepiece at strange, eight-legged creatures clambering over the moss.“They were impressed,” Dr. De Cian said.But she was not finished with the tiny beasts, known as tardigrades. She brought them to her laboratory at the French National Museum of Natural History, where she and her colleagues hit them with gamma rays. The blasts were hundreds of times greater than the radiation required to kill a human being. Yet the tardigrades survived, going on with their lives as if nothing had happened.Scientists have long known that tardigrades are freakishly resistant to radiation, but only now are Dr. De Cian and other researchers uncovering the secrets of their survival. Tardigrades turn out to be masters of molecular repair, able to quickly reassemble piles of shattered DNA, according to a study published on Friday and another from earlier this year.Scientists have been trying to breach the defenses of tardigrades for centuries. In 1776, Lazzaro Spallanzani, an Italian naturalist, described how the animals could dry out completely and then be resurrected with a splash of water. In the subsequent decades, scientists found that tardigrades could withstand crushing pressure, deep freezes and even a trip to outer space.In 1963, a team of French researchers found that tardigrades could withstand massive blasts of X-rays. In more recent studies, researchers have found that some species of tardigrades can withstand a dose of radiation 1,400 times higher than what’s required to kill a person.A preflight photo of a marine tardigrade as seen magnified by 40 times under a light microscope.Boothby Lab/ReutersWe are having trouble retrieving the article content.Please enable JavaScript in your browser settings.Thank you for your patience while we verify access. If you are in Reader mode please exit and log into your Times account, or subscribe for all of The Times.Thank you for your patience while we verify access.Already a subscriber? Log in.Want all of The Times? Subscribe. More

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    How 2 Families Faced a Catastrophic Birth Defect

    Ashlee Wiseman, a waitress at a Sizzler in Idaho Falls, Idaho, was 10 weeks pregnant when a nurse phoned with crushing news: a test of fetal DNA in her blood had found that her baby girl had trisomy 18, a catastrophic genetic abnormality, and was unlikely to survive.Devastated, she called her partner, Clint Risenmay, who was at work. He broke down in tears.Ashlee’s response was different.“A still small voice took over me,” she said. “I’m like, ‘I’m not going to listen to them. There has to be something that can help her. And there has to be someone who can help.’”A social media search led her to Dr. John Carey, a professor emeritus of pediatrics at the University of Utah, who has devoted his life to helping families dealing with trisomy 18. He supports pregnant women who chose abortion, but also helps couples who want to have babies with this rare condition, though most will be stillborn or die within a year.Ashlee and Clint were undeterred. They could do it, they assured Dr. Carey. They would lovingly care for a baby with complex medical needs.The consequences of trisomy 18 are dire. The babies have three copies of chromosome 18 instead of two and, as a result, have serious medical and developmental problems. Nearly all are unable to eat, walk or talk, and all have severe cognitive disabilities. They often need open-heart surgery and feeding and breathing tubes. Many women, after hearing what is in store, choose abortion.We are having trouble retrieving the article content.Please enable JavaScript in your browser settings.Thank you for your patience while we verify access. If you are in Reader mode please exit and log into your Times account, or subscribe for all of The Times.Thank you for your patience while we verify access.Already a subscriber? Log in.Want all of The Times? Subscribe. More