DeCode Genetics, a genome sequencing and drug development company, found out the hard way that predicting disease risk simply by reading someone’s genes isn’t so straightforward. On Tuesday, deCode filed for chapter 11 bankruptcy protection in Delaware. The company’s financial problems have also raised some troubling questions about genetic privacy.
DeCode’s mission was to uncover genetic risk factors for common diseases and to develop personal genome scans so individuals could learn their risk. DeCode quickly became the leader in the worldwide race to identify the causes of common disease. The company’s researchers discovered mutations linked to schizophrenia, heart disease, diabetes, prostate cancer and many other illnesses. Its approach was to identify the mutations first in Icelanders and then to confirm them in other populations [The New York Times]. Iceland was seen as an ideal spot for genetic studies, because the population was fairly isolated and the country has excellent medical and genealogical records. However, the company’s early successes did not translate into dollars, in part because the mutations they found only account for a small percentage of the overall incidence of a given disease.
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In very rare cases, the womb is a dangerous place for a developing fetus. Researchers have found that pregnant women can pass on cancer cells to their unborn babies, if those cancer cells carry a particular genetic mutation. The new study resolves a longstanding puzzle, because in theory any cancer cells that manage to cross the placenta into the baby’s bloodstream should be targeted for destruction by the child’s immune system. But there are records of 17 cases of a mother and baby appearing to share the same cancer – usually leukaemia or melanoma [BBC News].
In the study, which will be published in Proceedings of the National Academy of Sciences, researchers used a genetic “fingerprinting” technique to match the cancer cells found in a mother and baby. The case, involving a Japanese mother aged 28 and her daughter, revealed that both patients’ leukaemic cells carried the identical mutated cancer gene BCR-ABL1 even though the infant had not inherited this gene [The Times]. This meant that the child, who was diagnosed with cancer at the age of 11 months, could not have developed leukemia independently.
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For two squirrel monkeys nicknamed Dalton and Sam, life has gotten a lot more colorful. Researchers used gene therapy to correct the color blindness of the two adult monkeys, giving them the ability to distinguish between red and green for the first time. The fascinating accomplishment suggests that scientists may someday be able to cure other kinds of blindness in humans. And because the treated monkeys were “middle aged”, it challenges the assumption that gene therapies cannot work in adults because their brain connections are too set in their ways to change beneficially [New Scientist].
The field of gene therapy, in which a malfunctioning gene in a patient’s body is replaced with a functional one, fell into disarray one decade ago following the death of an 18-year-old in a clinical trial. But since then scientists have regrouped, using animal studies to probe the technique’s safety. Last year, researchers progressed to the point of safety trials in humans for the treatment of one rare eye condition called Leber congenital amaurosis, and were able to dramatically improve the patients’ sight. Those results were stunning, but they were also achieved in children, whose still-growing brains can rewire themselves on the fly in response to new sources of visual stimuli [Wired.com].
In the new study, published in Nature, the researchers used a type of squirrel monkey in which the males lack a visual pigment called L-opsin. Its absence renders the monkeys color-blind, unable to distinguish reds and green. Most of the females, on the other hand, see in full color. So the scientists got to wondering: what would happen if they gave a boy squirrel monkey the same opsin that girls have [Scientific American]. They used a harmless virus to ferry in the gene that makes opsin, injecting the virus behind the monkeys’ retinas.
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Some lucky people don’t groan awake to the alarm clock when they’ve only gotten six hours of sleep–instead they pop out of bed, bright-eyed and invigorated and ready for a new day. Now, researchers investigating the phenomenon of people who don’t need as much sleep as the rest of us have found a rare genetic mutation that accounts for some cases of shortened sleep cycles.
The scientists were searching the samples for variations in several genes thought to be related to the sleep cycle. In what amounts to finding a needle in a haystack, they spotted two DNA samples with abnormal copies of a gene called DEC2, which is known to affect circadian rhythms [The New York Times]. When they looked up the volunteers who had given the two DNA samples, they found a mother and daughter who habitually get about six hours of sleep each night and report no ill effects.
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The question of how salamanders regenerate their legs when amputated is an ancient one that dates back to the days of Aristotle. Now scientists have come one step closer to solving the mystery. Contrary to what researchers previously believed, when a salamander’s legs are removed the cells near the amputation site revert to adult stem cells, but do not become pluripotent, or capable of developing into any body part. That explains why a salamander who loses a tail doesn’t regrow a leg in its place.
In the study, published in Nature, scientists explain that when a salamander’s limb is amputated, the muscle, bone, and skin cells at the amputation site change into a clump of adult stem cells called a blastema. Before this experiment, researchers had hypothesized that these undifferentiated blastema cells — which all look identical — are pluripotent and thus able to form many different cells types. But it was not clear how the original cells from adult tissue were reprogrammed, or how the blastema cells went on to form the correct tissue types [Nature News].
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For six years, psychiatrists thought they had found a genetic clue as to what makes some people more prone to depression when they’re hit with an emotional blow: a single gene. A 2003 study created a sensation among scientists and the public because it offered the first specific, plausible explanation of why some people bounce back after a stressful life event while others plunge into lasting despair [The New York Times]. But now a broader analysis of 14 studies has found no link between the gene and the risk of depression, and researchers argue that the 2003 findings were prematurely heralded as a breakthrough. “I think what happened is that people who’d been working in this field for so long were desperate to have any solid finding” [The New York Times], says Kathleen R. Merikangas, one of the authors of the new study.
The so-called “depression gene” that researchers focused on in the 2003 study helps regulate levels of serotonin, a brain chemical that plays a major role in depression and is a key target of antidepressant drugs. Researchers … found from a long-term study of 847 people in New Zealand that those with a short version, or allele, of the serotonin transporter gene were more likely to become depressed by adverse life events than were those with only long alleles [ScienceNOW Daily News].
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Scientists have taken another step in cellular reprogramming that points the way towards the use of a patient’s own cells to treat genetic diseases. In a proof of concept study, researchers took skin cells from patients with a rare condition, Fanconi anemia, which causes skeletal problems and bone-marrow failure, and raises sufferers’ risk of cancer [Technology Review]. In the skin cells, the researchers fixed the genetic defects that caused the disease, and then reprogrammed the cells to act like stem cells capable of growing into any type of tissue.
The corrected stem cells could be grown into blood precursor cells for therapy. As these would carry a patient’s own DNA, except for the mutation responsible for the illness, they could be transplanted without risk of rejection by the body’s immune system [Times Online]. However, the patched up cells were not used to treat patients in this study, because it isn’t yet clear whether such cells are safe. Comments molecular geneticist Chris Mathew: “In future it may become possible to transfer the corrected stem cells back into the patient, but much work remains to be done before this can be transferred from the lab bench to the bedside” [The Scientist].
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A major new lawsuit is challenging the notion that human genes can be patented just like the latest mousetrap built by a basement inventor. The case focuses on two genes, BRCA1 and BRCA2, that are linked to a higher risk of breast and ovarian cancer, and which were patented by the company Myriad Genetics more than 10 years ago. Now, the ACLU has organized a lawsuit backed by organizations representing more than 100,000 doctors and geneticists, and will argue that the information contained in each person’s DNA should not be private property.
The plantiffs also include individual cancer patients like Genae Girard, who was diagnosed with breast cancer, and took Myriad’s genetic test to see if her genes also put her at increased risk for ovarian cancer, which might require the removal of her ovaries. The test came back positive, so she wanted a second opinion from another test. But there can be no second opinion [The New York Times]. Since Myriad owns the patent to both the two genes and the test that looks for them, no other company can develop a competing test.
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Researchers have found good evidence that the troubling sleep disorder narcolepsy is an autoimmune disease, in which the body’s own immune system attacks healthy brain cells. A new study published in Nature Genetics links narcolepsy to mutations of two genes involved in critical roles in protecting the body from disease. These two variations, they say, are likely conspirators against [cells that produce] hypocretin, a hormone that promotes wakefulness, and that narcoleptics have been found to lack [HealthDay News].
Narcolepsy is a disruptive disorder that can trigger “sleep attacks” without any warning during any normal activity. In addition, some people can experience “cataplexy”, where strong emotions such as anger, surprise, or laughter can trigger an instant loss of muscle strength, which, in some cases, can cause collapse [BBC News]. There is currently no cure for narcolepsy, although the symptoms can be largely controlled with a mix of stimulants and sleep-suppressing medications.
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Researchers have taken significant steps towards determining the mysterious causes of autism, with the discovery that two-thirds of autistic people have a genetic variant that influences how neurons connect with each other. An additional study found a link between autism and small “mistakes” in another DNA segment involved with cell communication. Both reports add weight to the idea that autism is related to problems with the way brain cells connect [Los Angeles Times].
The two studies were made possible by improved technology that allowed researchers to compare the genomes of thousands of autistic people to those of thousands of people without the disorder, looking for genetic differences between the two groups. Previous studies that have identified several genes that are implicated in autism, but … they are extremely rare and account for a very small proportion of autism [New Scientist]. The two studies, both published online by Nature, won’t lead immediately to new treatments, but they open up important new avenues of research.
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A $53 million effort drawing on the work of over 300 researchers has, after six years, produced something of great value to evolutionary biologists and farmers alike: the complete cow genome, which researchers say holds clues to the cow’s evolutionary history, as well as instructions on how to breed better cattle for milk and meat production. One research group sequenced the complete genome of a female Hereford cow, and researchers say that hidden in her roughly 22,000 genes are hints of how natural selection sculpted the bovine body and personality over the past 60 million years, and how man greatly enhanced the job over the past 10,000 [Washington Post]. Another spinoff research project studied the genetic variants between different breeds, and revealed some of the genetic keys to high-quality milk and beef.
Traits carried by bulls are important in determining how much milk a cow produces. Because bulls don’t make milk, however, a bull’s “performance profile” has to be sketched by observing the milk production of his daughters — a process that takes about six years and costs $25,000 to $50,000. Now, male calves can be tested at birth for milk-enhancing traits using gene-chip technology [Washington Post]. Early versions of these gene chips are already in use, ranchers say, but the new information may allow a new level of precision. Researchers also suggested that the genetic information could be used to breed cows that burp up less methane, a greenhouse gas that contributes to global warming.
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“People ordered genomes for Christmas” [The New York Times], says the chief executive of the personal gene-sequencing company Knome, commenting on the recent increased demand for his company’s services. Now, Knome is partnering with the non-profit X Prize Foundation to auction its complete genome scan service on eBay. Bidding will open at $68,000—far below Knome’s current price of $99,000. The auction starts Friday and will continue for 10 days. The highest bidder will walk away with a full readout of their gene map, along with a complete interpretation of their genetic details [CNN].
The auction is essentially a publicity stunt [The New York Times] for the company, and is set to begin Friday in order to coincide with DNA Day, the anniversary of the discovery of the double helix structure. Proceeds will benefit the X Prize Foundation, an educational institute offering a $10 million prize for the sequencing of 100 genomes in 10 days for less than $10,000 per genome. Knome and other personal genetics companies claim that besides identifying risk of diseases, sequencing can also determine an individual’s potential reaction to certain drugs and pick out those that may be ineffective or even toxic…. Genomics plays a critical role in the move towards personalized medicine [CNN].
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Cardiologist and author John Sotos has a theory about why Abraham Lincoln was so tall, why he appeared to have lumps on his lips and even why he had gastrointestinal problems. The 16th president, he contends, had a rare genetic disorder — one that would likely have left him dead of cancer within a year had he not been assassinated [Time]. But for Sotos to prove his case, he needs a snip from a historical relic: a piece of the bloodstained pillowcase on which the dying Lincoln rested his head after he was shot at Ford’s Theater on April 14, 1865.
The piece of cloth is displayed under glass at the Grand Army of the Republic Civil War Museum and Library in Philadelphia. Sotos has asked the museum’s board for a sample of the pillowcase, which is stained with both blood and brain matter. But the board is fiercely debating whether to concede to his request. “This is the Shroud of Turin of Civil War history,” said Andy Waskie, a board member…. “We are guardians in trusteeship of this extraordinarily important artifact. On the basis of pure science, the testing is of interest. We have not eliminated it as an option . . . but we want more information” [The Philadelphia Inquirer].
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Young adults with a genetic variant that increases their chance of developing Alzheimer’s later in life also have increased activity in the section of their brain devoted to memory, a new study has found. Researchers say the results suggest that the memory portion of the brain, the hippocampus, may eventually get worn out from a lifetime of overuse.
Researchers conducted fMRI brain scans of 36 volunteers, half of whom had at least one copy of the gene, known as APOE4. “We were surprised to see that even when the volunteers carrying APOE4 weren’t being asked to do anything, you could see the memory part of the brain working harder than it was in the other volunteers,” [study coauthor Christian] Beckmann said…. “Not all APOE4 carriers go on to develop Alzheimer’s, but it would make sense if in some people, the memory part of the brain effectively becomes exhausted from overwork and this contributes to the disease” [Reuters].
However, the researchers note that they’re far from proving this hypothesis, and say that it’s impossible to tell whether the extra activity contributes to Alzheimer’s symptoms later on or is just a sign of inefficient brain circuitry in the hippocampus [New Scientist].
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People with a family history of depression have an altered brain anatomy, a new study says, even if they themselves have never experienced clinical depression. Brain scans showed a 28-percent thinning in the right cortex — the outer layer of the brain — in people who had a family history of depression compared with people who did not. “The difference was so great that at first we almost didn’t believe it. But we checked and re-checked all of our data, and we looked for all possible alternative explanations, and still the difference was there” [Reuters], said study coauthor Bradley Peterson.
Researchers scanned the brains of 131 individuals ranging in age from 6 to 54, about half of whom came from families with a history of depression. The team was looking specifically for abnormalities in the brain that could signal a predisposition to depression, rather than changes that may be caused by the disease [Reuters]. The cortical thinning seems to fit the definition as a warning flag. Says Peterson: “That’s what is so extraordinary. You’re seeing it two generations later, and you’re seeing it in both children and adults…. And it’s present even if those offspring themselves have not yet become ill” [The New York Times].
The cerebral cortex is largely responsible for reasoning, planning, and mood, and researchers suggest that its thinning may interfere with a person’s ability to interpret social and emotional cues from others. Interestingly, not all of the subjects with depressed family members showed thinning on both sides of their cortices; it was primarily those with thinning in the left hemisphere who had actually developed depression.
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