Category Archives: Human Genetics

PUBLIC RELEASE DATE:

18-Dec-2014

Contact: Shozo Yokoyama syokoya@emory.edu PLOS

The evolution of trichromatic color vision in humans occurred by first switching from the ability to detect UV light to blue light (between 80-30 MYA) and then by adding green-sensitivity (between 45-30 MYA) to the preexisting red-sensitivity in the vertebrate ancestor. The detailed molecular and functional changes of the human color vision have been revealed by Shozo Yokoyama et al. Emory University and is published in the journal PLOS Genetics.

The molecular basis of functional differentiation is a fundamental question in biology. To fully appreciate how these changes are generated, it is necessary to evaluate the relationship between genes and functions. This is a difficult task because new mutations can produce different functional changes when they occur with different preexisting mutations, causing complex non-additive interactions.

The blue-sensitive visual pigment in human evolved from the UV-sensitive pigment in the ancient Boreoeutherian ancestor by seven mutations. There are 5,040 possible evolutionary paths connecting them. The team examined experimentally the genetic composition and color perception of the visual pigment at every evolutionary step of all 5,040 trajectories. They found that 4,008 trajectories are terminated prematurely by containing a dehydrated nonfunctional pigment. Eight most likely trajectories reveal that the blue-sensitivity evolved gradually almost exclusively by non-additive interactions among the seven mutations.

These analyses demonstrates that the historical sequence of change is critical to our understanding of molecular evolution and emphasizes that genetic engineering of ancestral molecules is the key to decode the complex interactions of mutations within a protein and their effects on functional change.

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The fine-tuning of human color perception

"The Government has run a comprehensive and transparent process over the lifetime of this Parliament to review the public acceptability of mitochondrial donation and the ongoing evidence of safety and efficacy of the new techniques involved, said public health minister Jane Ellison in a written statement.

The time is now right to give Parliament the opportunity to consider and vote on these regulations.

Around one in every 200 babies born in the UK has a severe mitochondrial disease. Although rare, the disorders can be passed to future generations through the maternal line.

Examples of mitochondrial diseases include conditions that cause muscle wasting, nerve damage, loss of sight and heart failure.

Chief Medical Officer, Professor Dame Sally Davies said: Mitochondrial donation will give women who carry severe mitochondrial disease the opportunity to have children without passing on devastating genetic disorders.

It will also keep the UK at the forefront of scientific development in this area.

If the new laws are voted in, it will be up to the fertility regulator, the Human Fertilisation and Embryology Authority (HFEA), to decide whether a treatment can go ahead on a case-by-case basis.

Mitochondrial transfer will only be allowed when there is a "significant risk" of disability or serious illness.

Children born after mitochondrial transfer will not be entitled to discover the identity of the "third parent" donor.

While many doctors and scientists applaud the move, pointing out that it could eliminate terrible diseases, critics argue "mitochondrial transfer" could lead to designer babies.

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Three parent babies given green light by government

Common methods used in human genetics analysis
Human genetics Human matings, like those of experimental organisms, show inheritance patterns both of the type discovered by Mendel (autosomal inheritance) and of sex linkage. Because controlled...

By: Nikolay #39;s Genetics Lessons

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Common methods used in human genetics analysis - Video

The sequencing of genomes of 48 bird species explains the evolutionary roots of vocalization and could offer insight into human speech disorders

Zebra finch offers clues to the evolution of vocalization. Credit: Peripitus/Wikimedia Commons

Songbirds stutter, babble when young, become mute if parts of their brains are damaged, learn how to sing from their elders and can even be "bilingual"in other words, songbirds' vocalizations share a lot of traits with human speech. However, that similarity goes beyond behavior, researchers have found. Even though humans and birds are separated by millions of years of evolution, the genes that give us our ability to learn speech have much in common with those that lend birds their warble.

A four-year long effort involving more than 100 researchers around the world put the power of nine supercomputers into analyzing the genomes of 48 species of birds. The results, published this week in a package of eight articles in Science and 20 papers in other journals, provides the most complete picture of the bird family tree thus far. The project has also uncovered genetic signatures in song-learning bird brains that have surprising similarities to the genetics of speech in humans, a finding that could help scientists study human speech.

The analysis suggests that most modern birds arose in an impressive speciation event, a "big bang" of avian diversification, in the 10 million years immediately following the extinction of dinosaurs. This period is more recent than posited in previous genetic analyses, but it lines up with the fossil record. By delving deeper into the rich data set, research groups identified when birds lost their teeth, investigated the relatively slow evolution of crocodiles and outlined the similarities between birds' and humans' vocal learning ability, among other findings.

The vocal learning discoveries could have important implications for the study of human speech and its disorders. If the genes are similar, "you can study in song birds and test their function in a way you can't do in humans," says Erich Jarvis, one of the leaders of the international effort and an associate professor of neurobiology at Duke University.

Scientists have long used songbirds, typically zebra finches, to probe questions about how language can be learned because not many other species have this ability. "Among primates, Homo sapiens are the only species that can modify vocalization," says Stephanie White, a neuroscientist and professor of integrative biology and physiology at the University of California, Los Angeles, who was not involved in the new research.

That's not to say that other primates don't communicate vocally, but White explains that the grunts, screeches and hoots uttered by chimpanzees, for example, are more automatic. Although an older, bigger chimp may have a deeper voice, "a young chimp and an old chimp sound pretty much the same," she says. Humans and songbirds, on the other hand, progress from baby talk to complex vocalizations. The handful of other species with this abilitythe vocal learnersincludes dolphins, sea lions, bats and elephants.

The new work on vocal learning relied on laser dissection of brain regions of zebra finches known to be involved in vocalizations and then analysis of gene activity there. The researchers then compared those levels to gene expression levels in human brains. They found that humans and birds share 55 genes between brain regions important for vocal learning, a good handful of which were involved in forming connections between neurons. Analysis of genes in other avian vocal learners parrots and hummingbirdsechoed the finding.

Another paper shows that 10 percent of the genome in song-learning birds is dedicated to song. White, who found both papers to be "very powerful," explains that these genes are actively regulated during vocalization. In humans, a simple phone conversation is actually an intensely focused activity that sets off cascades gene regulation across the brain, she says.

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Massive Genetic Effort Confirms Bird Songs Related to Human Speech

Margaret Thompson was one of Canadas most respected geneticists, a pioneer in genetic counselling and a devoted researcher into the causes of certain diseases.

She also participated in one of the darker chapters in this countrys history.

Hailed as a gifted scientist who had a lasting impact on Canadas health care system, Dr. Thompson also served for two years on the Alberta Eugenics Board, which approved the forced sterilization of individuals deemed unfit to reproduce.

Margaret (Peggy) Anne Wilson Thompson, who died in Toronto on Nov. 3 at the age of 94, was born on the Isle of Man, in England, on Jan. 7, 1920, and was six years old when her family moved to Saskatchewan. Like many young women at the time, she completed teacher training, and taught in rural schools for two years. She graduated from the University of Saskatchewan in 1943 with a degree in biology, and completed a PhD in zoology, specializing in metabolic genetics, from the University of Toronto in 1948.

She spent two years teaching at the University of Western Ontario before moving to the University of Alberta in Edmonton, where she taught zoology and started the Hereditary Genetic Counselling clinic. She also served on the Alberta Eugenics Board from 1960 to 1962, which authorized the sterilization of institutionalized mentally defective people who presented the danger of procreation if discharged and risked transmission of [their] disability to potential children. She was the boards last surviving member, according to the Living Archives on Eugenics in Western Canada.

Eugenics was introduced in 1883 by Francis Galton, who was Charles Darwins cousin, to apply the ideals behind the selective breeding of plants and animals to humans in order to weed out defects, including insanity, criminality and mental incompetence, and improve the quality of the human gene pool. It is widely dismissed today as pseudo-science and a violation of basic human rights.

Founded in 1928 to implement Albertas Sexual Sterilization Act, the rotating, four-person eugenics board approved the mostly involuntary sterilization of 2,834 individuals until it was shut down, and the act repealed, in 1972 by the government of then-premier Peter Lougheed. The only other eugenics board in Canada existed in British Columbia from 1933 to 1973.

In 1999, then-premier Ralph Klein apologized for the Alberta boards work and offered millions of dollars in compensation to survivors.

Dr. Thompsons death notice, the many online condolences and tributes, various biographies, her entry in the Canadian Encyclopedia and, most notably, her 1988 Order of Canada citation none makes any mention of her involvement on the eugenics board. Instead, they focus on the life and work of a protean scientist, mentor and teacher.

[Eugenics] was not a subject that I recall her speaking about, said her son Bruce Thompson, until the mid-1990s, when she informed us that the actions of the board were being investigated and that her testimony would be required. Other than knowing that she was giving testimony in Alberta, I recall no further conversations with her on this matter.

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Gifted scientist Margaret Thompson had a lasting impact on health care

Creationism. Human Genetics Confirms the Bible. Dr. Robert Carter
Origins With Dr. Robert Carter #39; #39;Genetics Adam Our Ancestor #39; #39; Geneticist Dr. Robert Carter gives incredible DNA evidence that entire human population came f...

By: Max Bauer

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Creationism. Human Genetics Confirms the Bible. Dr. Robert Carter - Video

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Newswise (SALT LAKE CITY) Examination of DNA from 21 primate species from squirrel monkeys to humans exposes an evolutionary war against infectious bacteria over iron that circulates in the hosts bloodstream. Supported by experimental evidence, these findings, published in Science on Dec. 12, demonstrate the vital importance of an increasingly appreciated defensive strategy called nutritional immunity.

Weve known about nutritional immunity for 40 years, says Matthew Barber, Ph.D., first author and postdoctoral fellow in human genetics at the University of Utah. What this study shows us is that over the last 40 million years of primate evolution, this battle for iron between bacteria and primates has been a determining factor in our survival as a species. The study also models an approach for uncovering reservoirs of genetic resistance to bacterial infections, knowledge that could be used to confront emerging diseases.

Following infection, the familiar sneezing, runny nose, and inflammation are all part of the immune systems attempts to rid the body of hostile invaders. Lesser known is a separate defense against invasive microbes, called nutritional immunity, that quietly takes place under our skin. This defense mechanism starves infectious bacteria by hiding circulating iron, an essential nutrient it needs for survival. The protein that transports iron in the blood, transferrin, tucks the trace metal safely out of reach.

Clever as it sounds, the ploy is not enough to keep invaders at bay. Several bacterial pathogens - including those that cause meningitis, gonorrhea, and sepsis - have developed a weapon, transferrin binding protein (TbpA), that latches onto transferrin and steal its iron. Though scientists have known of the offensive strategy, they failed to realize how pivotal the battle over iron has been in the conflict between host and pathogen.

Interactions between host and pathogen are transient and temporary, says senior author Nels Elde, Ph.D., assistant professor of human genetics at the University of Utah. It took casting a wide net across all of primate genetic diversity to capture the significance.

Just as details of a struggle can be gleaned from battle scars, Barber and Elde reconstructed this evolutionary conflict by documenting when and where changes in transferrin and TbpA have occurred over millennia. They examined the DNA of transferrin in 21 species from the primate family tree, and of TbpA from dozens of bacterial strains. The majority of accumulated changes in transferrin and TbpA cluster around a single region of contact between the two proteins, highlighting it as a site of evolutionary conflict between host and pathogen. The authors then used these genetic observations as a guide to perform experiments, which showed changes in TbpA enable the protein to grasp hold of transferrin, and that recent changes in transferrin allow it to evade TbpA.

Up to 25 percent of people in the worlds populations have a small alteration in the transferrin gene, which prevents recognition by several infectious bacteria, the most recent sign of this long battle. Up until this study no one had come up with a functional explanation for why this variation occurs at an appreciable frequency in human populations, says Elde. We now know that it is a consequence of the pathogens we and our ancestors faced over millions of years.

Understanding the strategies that underlie natural defense mechanisms, including nutritional immunity, could inform new approaches to combatting antibiotic-resistant bacteria and emerging diseases. By examining the natural conflicts that have played out for millions of years, we can determine what has worked, and apply them in new situations, says Elde.

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Human DNA Shows Traces of 40 Million-Year Battle For Survival Between Primate and Pathogen

PUBLIC RELEASE DATE:

11-Dec-2014

Contact: Glenna Picton picton@bcm.edu 713-798-4710 Baylor College of Medicine @bcmhouston

EMBARGOED for release Thursday, Dec. 11, 2014, at 12 p.m. ET

HOUSTON - (Dec. 11, 2014) - The ancient Japanese art of origami is based on the idea that nearly any design - a crane, an insect, a samurai warrior - can be made by taking the same blank sheet of paper and folding it in different ways.

The human body faces a similar problem. The genome inside every cell of the body is identical, but the body needs each cell to be different -an immune cell fights off infection; a cone cell helps the eye detect light; the heart's myocytes must beat endlessly.

Appearing online this week in the journal Cell, researchers at Baylor College of Medicine, Rice University, the Broad Institute of MIT and Harvard, and Harvard University describe the results of a five-year effort to map, in unprecedented detail, how the 2-meter long human genome folds inside the nucleus of a cell. Their results show that the cell-- like a microscopic origamist - modulates its function by folding the genome into an almost limitless variety of shapes.

A centerpiece of the new study is the first reliable catalog of loops spanning the entire human genome. For decades, scientists have examined the regions in the close vicinity of a gene to understand how it is regulated. But as the genome folds, sequences far from a gene loop back and come in contact with those nearby elements.

Looping has been a blind spot for modern biology. "For over a century, scientists have known that DNA forms loops inside of cells, and that knowing where the loops are is incredibly important," said co-first author Suhas Rao, a researcher at the Center for Genome Architecture at Baylor. "But mapping the positions of all those loops was long thought to be an insurmountable challenge."

The researchers showed that the 3 billion DNA letters of the human genome are partitioned into roughly 10,000 loops, a surprisingly small number. (Prior work on loops had suggested that the genome contains over a million.)

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Scientists map the human loop-ome, revealing a new form of genetic regulation

It's not just great minds that think alike. Dozens of the genes involved in the vocal learning that underpins human speech are also active in some songbirds. And knowing this suggests that birds could become a standard model for investigating the genetics of speech production and speech disorders.

Complex language is a uniquely human trait, but vocal learning the ability to pick up new sounds by imitating others is not. Some mammals, including whales, dolphins and elephants, share our ability to learn new vocalisations. So do three groups of birds: the songbirds, parrots and hummingbirds.

The similarities between vocal learning in humans and birds are not just superficial. We know, for instance, that songbirds have specialised vocal learning brain circuits that are similar to those that mediate human speech.

What's more, a decade ago we learned that FOXP2, a gene known to be involved in human language, is also active in "area X" of the songbird brain one of the brain regions involved in those specialised vocal learning circuits.

Andreas Pfenning at the Massachusetts Institute of Technology and his colleagues have now built on these discoveries. They compared maps of genetic activity transcriptomes in brain tissue taken from the zebra finch, budgerigar and Anna's hummingbird, representing the three groups of vocal-learning birds.

They then compared these genetic maps with others taken from birds and primates that can't learn new vocalisations, and with maps taken from the brains of six people who donated tissue to the Allen Brain Institute in Seattle.

Their results showed that FOXP2 is just one of 55 genes that show a similar pattern of activity in the brains of humans and the vocal-learning birds. Those same genes show different patterns of activity in the brains of animals incapable of vocal learning.

"The similarities are beyond one or a handful of genes," says Pfenning. "There are just systematic molecular similarities between song-learning birds and humans."

The findings suggest that songbirds might make ideal animal models for studying the genetics of speech production.

"There's potential for songbirds to be used to study neurodegeneration especially conditions like Huntington's," says Pfenning. Huntington's disease affects the ability to produce complex motor behaviour, such as singing and talking, so experiments with birds might implicate particular genes in the disease.

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Humans and birds share the same singing genes

Media reports about behavioural genetics unintentionally induce unfounded beliefs, therefore going against the educational purpose of scientific reporting, writes the University of Montreals Alexandre Morin-Chass, following his study of 1,500 Americans. Among other things, we wanted to know if the public understood (or misunderstood) popular science articles about a new research field, genopolitics, and whether this popularization indeed helped people have an informed opinion on human genetics, Morin-Chass explained.

The study participants first had to read a news article about research on the influence of a gene on one of the following three traits: breast cancer, political ideology (liberal or conservative), or the tendency to go into debt. After reading the article assigned to them, they were then asked to estimate the influence of genetics on various biological (e.g., hair colour, height) or behavioural (e.g., violence, alcoholism) traits on a scale from 0% genetic to 100% genetic. They were told that there were no right or wrong answers. The purpose of the study was simply to examine the interpretation of facts.

The conclusions were troubling, to say the least. Morin-Chass observed that after reading an article published in the British Daily Telegraph in October 2010 about a "gene responsible for liberal ideas, the readers tended to generalize the influence of genetics to other behaviours or social orientations of which there was no mention in the news article (including sexual orientation and intelligence). The same phenomenon was observed among the readers of the other article, originally published in the Scientific American Mind magazine in June 2010, which associated a gene with susceptibility to debt.

However, public misunderstanding is not the only thing to blame for this misinterpretation. Generally, science reporters first goal is to inform the public about scientific developments. However, this practice is not disinterested; some news is purposely written in a manner intended to catch the publics attention with startling results in order to increase or to maintain market shares," Morin-Chass explained.

Genetic research into behaviour is certainly a minefield. It is often associated with other more controversial theoretical work, for example, in sociobiology, which attempts to explain social inequalities using the theory of evolution and the concept of natural selection. In contrast, current trends in research are based on empirical analysis of DNA data.

"Personally, I am in favour of this innovative approach to better understand our world, but I cant argue with the facts: the field is often misunderstood or even disregarded, Morin-Chass said. Some reduce it to its most deterministic form. The danger, which, in my mind, is present, is that scientific research findings could be manipulated for ideological purposes by certain social groups. Hence the importance of making sure the public understands the scope and limitations of such research.

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The above story is based on materials provided by Universit de Montral. Note: Materials may be edited for content and length.

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Current practices in reporting on behavioural genetics can mislead the public