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In the western world, marriage between first cousins is labeled incest or inbreeding, and in the United States the practice is banned or restricted in 31 states. But a new essay argues that such laws are based on an outdated notion of the genetic risks involved in cousins marrying and reproducing. [T]hose laws “seem ill-advised” and “should be repealed,” a geneticist and medical historian write…. “Neither the scientific nor social assumptions that informed them are any longer defensible” [Scientific American].

First cousins share about an eighth of their genes, and are therefore more likely to receive two copies of some recessive gene that poses health problems. Scientists had assumed that the children of first cousins would therefore be more likely to be born with birth defects. But coauthor Hamish Spencer writes that the risk of congenital defects is about 2 per cent higher than average for babies born to first-cousin marriages – with the infant mortality about 4.4 per cent higher – which is on a par with the risk to babies born to women over 40. “Women over the age of 40 have a similar risk of having children with birth defects and no one is suggesting they should be prevented from reproducing,” said Professor Spencer [The Independent].

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The small band of Homo sapiens that left Africa around 60,000 years ago, taking the first steps on a journey that would eventually disperse humans all around the world, may have been composed mostly of men. A new analysis of DNA variations in contemporary humans indicates that non-Africans descend from a population that contained far more males than females [New Scientist].

In the study, published in Nature Genetics [subscription required], researchers compared genetic samples from present-day African, European, and Asian populations. They were looking at the chromosomes that determine sex (two X chromosomes in women, one X and one Y chromosome in men), as well as the other 22 chromosome pairs, which are the same in both sexes. They examined the rate at which mutations randomly spread through the X chromosome over dozens or hundreds of generations as compared to the mutation rate in other, non-sex, chromosomes [AFP].

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Researchers recently went to an Amish community in Pennsylvania with an odd request: Will you drink milkshakes for the sake of science? In a study about cardiovascular health and genetics that had more than 800 Amish people slurping high-fat shakes, researchers discovered that about five percent of their subjects had a genetic mutation that defends the heart against the effects of a high-fat diet—specifically, breaking down triglycerides, those fats that clog arteries like hair in your bathroom drain [Newsweek].

In the study, published in Science [subscription required], Amish men and women agreed to drink a rich milkshake that was made mostly of heavy cream. Over the next six hours, a group of investigators took samples of their blood, determining how much fat was churning through their bloodstreams. Most of the study participants responded as expected — their levels of triglycerides, a common form of fat in the blood, rose steadily for three to four hours and then declined. But about 5 percent had an extraordinary reaction: their triglyceride levels started out low and hardly budged [The New York Times].

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The Vatican has issued new ethical guidelines in response to the biomedical advances of the last 20 years, and has come down hard on assisted reproduction technologies and genetic engineering. The document, Dignitas Personae (which translates as “human dignity”), reaffirm the church’s opposition to in vitro fertilization. It also tells Catholics that the church also doesn’t condone “adopting” leftover fertilized embryos from fertility clinics, and frowns upon the genetic testing of embryos before implantation, which could lead to the embryo being discarded. The Vatican says these techniques violate the principles that every human life — even an embryo — is sacred, and that babies should be conceived only through intercourse by a married couple [The New York Times].

These instructions stem from two fundamental theological principles: that life begins at conception and that the origin of human life is the “fruit of marriage.” … The document now makes clear that the morning-after pill, RU-486, and intrauterine devices (IUDs), which either intercept the embryo before implantation or eliminate it after implantation, “fall within the sin of abortion” [Scientific American]. The guidelines may come as a surprise to many Catholics who don’t realize that the church takes such a strict stance on medical technologies like in vitro fertilization that are often seen as routine and beneficial.

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The tumult of the Spanish Inquisition, which began over 500 years ago, has echoed down through the generations of people living on the Iberian peninsula in a remarkable way. A new genetic study has revealed that many current Spaniards have Sephardic Jewish or North African heritage, indicating that their ancestors converted to Christianity during the religious upheaval of the 15th century in order to remain in Spain. The study showed that one in ten Iberians has a North African ancestor, while one in five had Jewish forebears.

This melting pot probably occurred after centuries of coexistence and tolerance among Muslims, Jews and Christians ended in 1492, when Catholic monarchs converted or expelled the Islamic population, called Moriscos. Sephardic Jews, whose Iberian roots extend to the first century AD, received much the same treatment. “They were given a choice: convert, go, or die,” says Mark Jobling, a geneticist at the University of Leicester, UK. Some of those that became Christian would have ended up contributing genes to the Iberian pool [New Scientist].

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In a landmark court case, a European court has ruled that law enforcement agencies can’t keep DNA samples from people who have never been convicted of a crime. In the unanimous judgment, the European Court of Human Rights ruled that keeping the samples was in violation of people’s right to a private life, a protection under the Human Rights Convention [AP].

Its decision, which is binding on all 46 members of the Council of Europe, will have an immediate impact on around 850,000 innocent people whose genetic profiles are stored on the police DNA database in England and Wales [The Economist]. In those parts of the United Kingdom, the police collect a DNA sample from anyone arrested on a “recordable” offense, a category that includes everything from murder to “fraudulently evading bingo duty.” That sample is stored for the rest of the person’s life, even if they’re never convicted of the crime they were arrested for. If the U.K. doesn’t appeal the new ruling, the English and Welsh police will have to immediately destroy the genetic profiles of everyone without a criminal record.

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Researchers may have uncovered one of the universal causes of aging: A crucial type of protein that serves a double duty in organisms ranging from yeast to mice, and that becomes overwhelmed as the organism ages. The protein is charged both with repairing DNA damage and with regulating gene expression (so that, for example, a gene necessary for liver function doesn’t suddenly get turned on in the brain), and a new study has shown that when the protein is busy repairing DNA, it can’t perform its other task. Says lead author David Sinclair: “One idea of why we age is that DNA becomes damaged or mutated…. But perhaps the main culprit is the effect of genes switching on and off, and that should be reversible” [Wired News].

About a decade ago, researchers identified a protein called Sir2 that zooms to the spot of broken DNA in yeast cells and repairs the breaks. But to do that, Sir2 has to abandon its job of inactivating a sterility gene elsewhere in the yeast genome. The result is yeast cells that have intact DNA but are sterile, a symptom of aging in the fungi…. “This may be a very fundamental Achilles’ heel of life,” says Sinclair [ScienceNOW Daily News]. Now, Sinclair’s team has identified the mammalian equivalent of that protein, called SIRT1, and have determined that it plays a similar role in aging mice: When it focuses on repairing DNA damage, it neglects its gene regulation duties.

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About 4,600 years ago in Germany’s fertile farm country a group of stone age people met a violent end, but the arrangement of their skeletons in four graves tells a story of love and family bonds. One particularly well-preserved grave holds what researchers say is the first known nuclear family, with an adult male and female cradling the bodies of their two sons. A DNA analysis of the skeletons’ bones and teeth confirmed their blood ties: “The two kids have her mitochondrial DNA, and his Y chromosome - that’s a nuclear family,” says molecular anthropologist Brian Kemp [New Scientist].

The group of 13 individuals includes adults aged 25 to 60 and children under the age of 9, and researchers believe that they were massacred. Says study coauthor Alistair Pike: “They were definitely murdered, there are big holes in their heads, fingers and wrists are broken.” At least five of the individuals show the effects of a violent attack, one even had the tip of a stone weapon embedded in a vertebra [BBC News].

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In a remarkable announcement, German researchers have declared that they “functionally cured” a patient of AIDS, eradicating all traces of the virus from his body. The feat was accomplished with a bone marrow transplant from a donor who had a genetic resistance to the virus, and researchers say that 20 months later they can find no trace of the virus in the patient’s blood, bone marrow, or organ tissue.

But the accomplishment shouldn’t be taken as a sign that a cure for the 33 million people living with AIDS is around the corner, researchers are hasty to add. Professor Rodolf Tauber from the [German] clinic said: “This is an interesting case for research. But to promise to millions of people infected with HIV that there is hope of a cure would not be right” [BBC News]. Reasons for this caution include the small number of potential donors with the HIV-resistant mutation, and the difficulty and expense of bone marrow transplants.

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Injury to nerve cells in the brain and spinal cord, once considered permanent, may be reversible after all. A pair of new studies demonstrate how to override two biological mechanisms that prevent damaged cells of the central nervous system from regrowing. The first obstacle are genes that prevent nerve growth and the second are chemical signals that repress nerve growth.

In the first study, published in Science [subscription required], Harvard researchers identified a gene, PETN, that inhibits the major growth pathway in nerve cells. They created genetically modified “knock-out” mice that lacked the gene. Normally, axons in the optic nerve of adult mice do not regenerate when crushed—and worse yet, about 80% of the neurons with severed axons die. But in mice lacking PTEN, 50% of neurons survived and about 10% of axons in the optic nerve regrew—as far as 4 millimeters in 28 days. “To have any manipulation that can make these axons grow from where they were severed near the retina all the way down the optic nerve is just amazing,” [ScienceNOW Daily News] commented neurobiologist Ben Barres.

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For the first time researchers have sequenced the complete genome of a cancer cell, and they say the process turned up eight previously unknown genetic mutations that played a role in the patient’s terminal leukemia. As it gets cheaper and easier to decode entire genomes, as opposed to just checking “usual suspect” stretches of DNA, doctors hope to decode the genomes of many different types of cancer. Eventually, researchers say cheap techniques may allow doctors to study the cancer genomes of individual patients.

Lead researcher Richard Wilson said he hoped that in 5 to 20 years, decoding a patient’s cancer genome would consist of dropping a spot of blood onto a chip that slides into a desktop computer and getting back a report that suggests which drugs will work best.“That’s personalized genomics, personalized medicine in a box,” he said. “It’s holy grail sort of stuff, but I think it’s not out of the realm of possibility” [The New York Times].

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The chicken industry has been remarkably effective in breeding efficient egg-layers and plump-breasted broilers, but a new study says that focus has created a chicken population that lacks genetic diversity, leaving the birds more vulnerable to diseases. The study found that industrial chickens have lost about half of the genetic variations once found in the wild chicken populations, and some have lost 90 percent of those genes.

This means most of the world’s chickens lack characteristics that evolved when they lived in the wild, and may be useful again to help them face stress and disease as livestock. Scientists want to breed DNA for traits such as disease resistance, or “animal well-being”, back into commercial birds without introducing undesirable traits at the same time [New Scientist]. Researchers say the biggest concern is that if commerical chickens are nearly identical genetically they’ll all be susceptible to the same infectious diseases, and an outbreak of of a ailment like avian flu could devastate the entire industry.

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In a big step forward for cloning research, scientists have produced healthy clones of mice that were dead and frozen for 16 years. Researchers say the new technique could allow conservationists to freeze tissue from endangered species, which could then be used to produce clones if those species become extinct. The finding also raises hopes of one day being able to resurrect extinct animals frozen in permafrost, such as the woolly mammoth, says [lead researcher] Teruhiko Wakayama…. “It would be very difficult, but our work suggests that it is no longer science fiction,” he says [New Scientist].

Researchers have previously produced clones from frozen animal tissue, but only from specimens that were preserved with special chemicals to protect cells from damage during the deep freeze. In this study, published in the Proceedings of the National Academy of Sciences [subscription required], no such special precautions were taken when the mice were stowed in a freezer 16 years ago. Many zoos are not in a position to collect cells and freeze them in such a way as to preserve their viability, says [cloning expert] Robert Lanza … but they can put a dead animal “in a plastic bag and throw it in the freezer”, he adds. “With a kitchen freezer you could store the genetic diversity of every panda in existence” [New Scientist].

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The Phoenician culture vanished from the Mediterranean following the fall of Carthage in 146 BC, when the Romans razed the city and (according to legend) salted the earth, but the Phoenician people didn’t fade away. A new genetic analysis shows that 1 in 17 men in the Mediterranean region have Phoenician DNA, and must be descended from those ancient seafarers.

The findings could fill a gap in the history of the Phoenician civilization, which originated two to three thousand years ago in the eastern Mediterranean—in what is now Lebanon and Syria—and included prominent traders, according to Chris Tyler-Smith, lead author…. “By the time of the Romans they more or less disappeared from history, and little has been known about them since” [National Geographic News].

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The oldest human to have his complete mitonchondrial (mtDNA) genome sequenced, a 5,000-year-old “Iceman” mummy known as Ötzi, does not appear to have any living relatives in Europe. The new genetic analysis reveals that Ötzi belonged to a previously unknown branch of human evolution. Said study coauthor Franco Rollo: “Apparently, this genetic group is no longer present…. We don’t know whether it is extinct or it has become extremely rare” [HealthDay News].

The researchers extracted DNA from Iceman’s rectum. They analyzed the genome of the cells’ energy-making structures, called mitochondria. “You only get mitochondrial DNA from your mother, and she gets it from her mother and so on, so it forms an unbroken link all the way back to the common maternal ancestor of all of us,” said researcher Martin Richards [LiveScience]. Earlier studies of fragments of Ötzi’s mtDNA had indicated that he was of the K1 lineage, which is further divided into three branches. But after comparing his complete mtDNA genome with that of 115 modern Europeans of K1 lineage, the researchers found three mutations that place Ötzi in a fourth, previously unknown, branch of K1.

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