Category Archives: Human Genetics

Entrepreneurial Achievement Award: Bradley Dixon, MD
http://www.cincinnatichildrens.org Entrepreneurial Achievement Award Bradley P. Dixon, MD Division of Nephrology and Hypertension Assistant Professor of Pedi...

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TUESDAY, Feb. 18, 2014 (HealthDay News) -- Cat lovers have long known that the distinctive three-toned calico patterning is almost exclusively found in female felines.

Now, the genetics behind that anomaly may help scientists understand human DNA a little better, too.

That's because calico cats may help explain so-called gene silencing -- flipping the "off switch" on genes, researchers say.

A team at the University of California, San Francisco say the unique orange-white-and-black patchwork fur on these cats is due to the silencing or inactivation of one of their two X chromosomes.

As the researchers explained, cells in female mammals have two copies of the X chromosome -- one from the mother and one from the father. Cells require only one active X chromosome, so the second one is turned off.

Calico cats have an orange-fur-color gene on one of their X chromosomes and a black-fur gene on the other. According to the UCSF team, the random silencing of one of the X chromosomes in each cell results in the calico cats' unique patchwork coat.

Scientists don't know exactly how a cell turns off a chromosome, so the researchers are trying to learn more about how different kinds of genes can be switched on or off without affecting the underlying DNA sequence.

This knowledge could lead to improved understanding, diagnosis and treatment of X-chromosome-related diseases in humans, said the researchers, who are scheduled to present their findings Tuesday at the Biophysical Society's annual meeting in San Francisco.

"Uncovering how only one X chromosome is inactivated will help explain the whole process of 'epigenetic control,' meaning the way changes in gene activity can be inherited without changing the DNA code," Elizabeth Smith, a postdoctoral fellow in the anatomy department at UCSF, said in an American Institute of Physics news release.

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Calico cats may help scientists understand human genetics

Some Elementary Human Genetics Human Anatomy Physiology Study Course Review
CLICK HERE: http://bit.ly/1gtILzv All structures and musculature are modeled and labeled including nerves, deep and superficial muscles, blood supply, skelet...

By: Neerali Padhiar

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Some Elementary Human Genetics Human Anatomy & Physiology Study Course Review - Video

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13-Feb-2014

Contact: Clare Ryan clare.ryan@ucl.ac.uk 44-020-310-83846 University College London

The interactive map, produced by researchers from Oxford University and UCL (University College London), details the histories of genetic mixing between each of the 95 populations across Europe, Africa, Asia and South America spanning the last four millennia.

The study, published this week in Science, simultaneously identifies, dates and characterises genetic mixing between populations. To do this, the researchers developed sophisticated statistical methods to analyse the DNA of 1490 individuals in 95 populations around the world. The work was chiefly funded by the Wellcome Trust and Royal Society.

'DNA really has the power to tell stories and uncover details of humanity's past.' said Dr Simon Myers of Oxford University's Department of Statistics and Wellcome Trust Centre for Human Genetics, co-senior author of the study.

'Because our approach uses only genetic data, it provides information independent from other sources. Many of our genetic observations match historical events, and we also see evidence of previously unrecorded genetic mixing. For example, the DNA of the Tu people in modern China suggests that in around 1200CE, Europeans similar to modern Greeks mixed with an otherwise Chinese-like population. Plausibly, the source of this European-like DNA might be merchants travelling the nearby Silk Road.'

The powerful technique, christened 'Globetrotter', provides insight into past events such as the genetic legacy of the Mongol Empire. Historical records suggest that the Hazara people of Pakistan are partially descended from Mongol warriors, and this study found clear evidence of Mongol DNA entering the population during the period of the Mongol Empire. Six other populations, from as far west as Turkey, showed similar evidence of genetic mixing with Mongols around the same time.

'What amazes me most is simply how well our technique works,' said Dr Garrett Hellenthal of the UCL Genetics Institute, lead author of the study. 'Although individual mutations carry only weak signals about where a person is from, by adding information across the whole genome we can reconstruct these mixing events. Sometimes individuals sampled from nearby regions can have surprisingly different sources of mixing.

'For example, we identify distinct events happening at different times among groups sampled within Pakistan, with some inheriting DNA from sub-Saharan Africa, perhaps related to the Arab Slave Trade, others from East Asia, and yet another from ancient Europe. Nearly all our populations show mixing events, so they are very common throughout recent history and often involve people migrating over large distances.'

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Interactive map of human genetic history revealed

Lawrence LeBlond for redOrbit.com Your Universe Online

A multi-institutional team of researchers this week published in the journal Science a study identifying, dating and characterizing the genetic mixing between populations around the world. Along with the study, the team released an interactive map detailing the histories of this genetic mixing.

Researchers from Max Planck Institute for Evolutionary Anthropology, Oxford University and University College London developed sophisticated statistical methods to analyze the DNA of nearly 1500 people from 95 different populations around the world and from over the past four millennia. These populations hailed from Europe, Africa, Asia and South and Central America.

The groups work was funded by the Wellcome Trust and Royal Society.

DNA really has the power to tell stories and uncover details of humanitys past, said co-senior study author Dr Simon Myers, of Oxford Universitys Department of Statistics and Wellcome Trust Centre for Human Genetics.

Because our approach uses only genetic data, it provides information independent from other sources. Many of our genetic observations match historical events, and we also see evidence of previously unrecorded genetic mixing. For example, the DNA of the Tu people in modern China suggests that in around 1200CE, Europeans similar to modern Greeks mixed with an otherwise Chinese-like population. Plausibly, the source of this European-like DNA might be merchants travelling the nearby Silk Road, explained Dr Myers in a statement.

Dubbed Globetrotter, this powerful technique provides a good in-depth look at the past. For Instance, the method provided invaluable insight into the genetic legacy of the Mongol Empire. Historically, it is believed that the Hazara people of Pakistan are partially descended from Mongol warriors; the study found clear evidence to back up this belief, discovering that Mongol DNA had in fact entered the Pakistani population during the Mongol Empire. As well, six other neighboring populations showed similar evidence of genetic mixing with the Mongols during this period.

What amazes me most is simply how well our technique works, said study lead author Dr Garrett Hellenthal, of the UCL Genetics Institute. Although individual mutations carry only weak signals about where a person is from, by adding information across the whole genome we can reconstruct these mixing events. Sometimes individuals sampled from nearby regions can have surprisingly different sources of mixing.

For example, we identify distinct events happening at different times among groups sampled within Pakistan, with some inheriting DNA from sub-Saharan Africa, perhaps related to the Arab Slave Trade, others from East Asia, and yet another from ancient Europe. Nearly all our populations show mixing events, so they are very common throughout recent history and often involve people migrating over large distances, said Dr Hellenthal.

The team also identified chunks of DNA shared between individuals from different populations, based on the genome data taken from all 1490 individuals. They found that those populations that shared more ancestry also shared more of these chunks. As well, individual chunks gave the team clues about the underlying ancestry along chromosomes.

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New Interactive Map Reveals Human History Of Genetic Mixing

February 10, 2014

University of Oxford

Seven new genetic regions associated with type 2 diabetes have been identified in the largest study to date of the genetic basis of the disease.

DNA data was brought together from more than 48,000 patients and 139,000 healthy controls from four different ethnic groups. The research was conducted by an international consortium of investigators from 20 countries on four continents, co-led by investigators from Oxford Universitys Wellcome Trust Centre for Human Genetics.

The majority of such genome-wide association studies have been done in populations with European backgrounds. This research is notable for including DNA data from populations of Asian and Hispanic origin as well.

The researchers believe that, as more genetic data increasingly become available from populations of South Asian ancestry and, particularly, African descent, it will be possible to map genes implicated in type 2 diabetes ever more closely.

One of the striking features of these data is how much of the genetic variation that influences diabetes is shared between major ethnic groups, says Wellcome Trust Senior Investigator Professor Mark McCarthy from the University of Oxford. This has allowed us to combine data from more than 50 studies from across the globe to discover new genetic regions affecting risk of diabetes.

He adds: The overlap in signals between populations of European, Asian and Hispanic origin argues that the risk regions we have found to date do not explain the clear differences in the patterns of diabetes between those groups.

Among the regions identified by the international research team are two, near the genes ARL15 and RREB1, that also show strong links to elevated levels of insulin and glucose in the body two key characteristics of type 2 diabetes. This finding provides insights into the ways basic biochemical processes are involved in the risk of type 2 diabetes, the scientists say.

The genome-wide association study looked at more than 3 million DNA variants to identify those that have a measurable impact on risk of type 2 diabetes. By combining DNA data from many tens of thousands of individuals, the consortium was able to detect, for the first time, regions where the effects on diabetes susceptibility are rather subtle.

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Diabetes Genetics Study Brings In Data From Different Ethnic Groups

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An extra copy of chromosome 21 causes Down's syndrome but there is a dispute over who discovered it.

A disagreement over the discovery of the cause of Downs syndrome has resurfaced in France more than 50 years after the findings were published.

The dispute erupted again at the French Federation of Human Genetics' (FFGH) seventh biennial congress on human and medical genetics in Bordeaux at the end of last month.

Paediatric cardiologist Marthe Gautier, who was involved in the experiments that led to the identification of the extra copy of chromosome 21 the cause of the syndrome was due to relate her role in the discovery when two bailiffs arrived with a court authorization to record the session. The FFGH then decided at the last minute to cancel Gautier's presentation.

The bailiffs were representing the Paris-based Jrme Lejeune Foundation, which finances a large proportion of current Down's syndrome research in France. The foundation does not deny Gautiers contribution to the work leading to the discovery, but it credits the late Lejeune for the discovery itself.

Lejeune, a geneticist, was first author of the key paper reporting1 the finding, published by the French Academy of Sciences in January 1959. Gautier was listed as second author, and Raymond Turpin, a paediatric geneticist and Gautiers and Lejeunes boss at the Trousseau Hospital in Paris, was listed as third author.

The FFGH says that it wanted to honour Gautiers role in the discovery by giving her the floor and awarding her the federation's grand prize. Without questioning Jrme Lejeunes very important contribution to French genetics through the article on trisomy 21 and other work, we simply wanted to make a gesture in recognition of the determinant character of Marthe Gautiers contribution, the federation said in a statement.

But when the bailiffs walked in, we realized the recording might be used in a court case, FFGH treasurer and former president Dominique Bonneau told Nature. Not only do we not have the funds to fight a libel suit, but we felt it was inappropriate to hold the presentation under such strong legal pressure. Gautier received her prize discreetly and nine eminent geneticists signed a statement endorsing the decision to cancel the presentation.

Jean-Marie Le Mn, president of the Jrme Lejeune Foundation, says that the bailiffs were sent because the foundation wanted an official recording of the talk so that there could be no dispute over what was said. We needed to know what was said in case Jrme Lejeunes memory was smeared, he says.

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Down's syndrome discovery dispute resurfaces in France

Vogel and Motulsky #39;s Human Genetics Problems and Approaches
Vogel and Motulsky #39;s Human Genetics: Problems and Approaches http://tinyurl.com/p75exxp. .

By: danila aleshkevich

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Newswise Genetic adaptations for life at high elevations found in residents of the Tibetan plateau likely originated around 30,000 years ago in peoples related to contemporary Sherpa. These genes were passed on to more recent migrants from lower elevations via population mixing, and then amplified by natural selection in the modern Tibetan gene pool, according to a new study by scientists from the University of Chicago and Case Western Reserve University, published in Nature Communications on Feb. 10.

The transfer of beneficial mutations between human populations and selective enrichment of these genes in descendent generations represents a novel mechanism for adaptation to new environments.

The Tibetan genome appears to arise from a mixture of two ancestral gene pools, said Anna Di Rienzo, PhD, professor of human genetics at the University of Chicago and corresponding author of the study. One migrated early to high altitude and adapted to this environment. The other, which migrated more recently from low altitudes, acquired the advantageous alleles from the resident high-altitude population by interbreeding and forming what we refer to today as Tibetans.

High elevations are challenging for humans because of low oxygen levels but Tibetans are well adapted to life above 13,000 feet. Due to physiological traits such as relatively low hemoglobin concentrations at altitude, Tibetans have lower risk of complications, such as thrombosis, compared to short-term visitors from low altitude. Unique to Tibetans are variants of the EGLN1 and EPAS1 genes, key genes in the oxygen homeostasis system at all altitudes. These variants were hypothesized to have evolved around 3,000 years ago, a date which conflicts with much older archaeological evidence of human settlement in Tibet.

To shed light on the evolutionary origins of these gene variants, Di Rienzo and her team, led by first author Choongwon Jeong, graduate student at the University of Chicago, obtained genome-wide data from 69 Nepalese Sherpa, an ethnic group related to Tibetans. These were analyzed together with the genomes of 96 unrelated individuals from high-altitude regions of the Tibetan plateau, worldwide genomes from HapMap3 and the Human Genome Diversity Panel, as well as data from Indian, Central Asian and two Siberian populations, through multiple statistical methods and sophisticated software.

The researchers found that, on a genomic level, modern Tibetans appear to descend from populations related to modern Sherpa and Han Chinese. Tibetans carry a roughly even mixture of two ancestral genomes: one a high-altitude component shared with Sherpa and the other a low-altitude component shared with lowlander East Asians. The low-altitude component is found at low to nonexistent frequencies in modern Sherpa, and the high-altitude component is uncommon in lowlanders. This strongly suggested that the ancestor populations of Tibetans interbred and exchanged genes, a process known as genetic admixture.

Tracing the history of these ancestor groups through genome analysis, the team identified a population size split between Sherpa and lowland East Asians around 20,000 to 40,000 years ago, a range consistent with proposed archaeological, mitochondria DNA and Y chromosome evidence for an initial colonization of the Tibetan plateau around 30,000 years ago.

This is a good example of evolution as a tinkerer, said Cynthia Beall, PhD, professor of anthropology at Case Western Reserve University and co-author on the study. We see other examples of admixtures. Outside of Africa, most of us have Neanderthal genesabout 2 to 5 percent of our genomeand people today have some immune system genes from another ancient group called the Denisovans.

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The Genetic Origins of High-Altitude Adaptations in Tibetans

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9-Feb-2014

Contact: News & Information Office press.office@admin.ox.ac.uk 44-018-652-80530 University of Oxford

Seven new genetic regions associated with type 2 diabetes have been identified in the largest study to date of the genetic basis of the disease.

DNA data was brought together from more than 48,000 patients and 139,000 healthy controls from four different ethnic groups. The research was conducted by an international consortium of investigators from 20 countries on four continents, co-led by investigators from Oxford University's Wellcome Trust Centre for Human Genetics.

The majority of such 'genome-wide association studies' have been done in populations with European backgrounds. This research is notable for including DNA data from populations of Asian and Hispanic origin as well.

The researchers believe that, as more genetic data increasingly become available from populations of South Asian ancestry and, particularly, African descent, it will be possible to map genes implicated in type 2 diabetes ever more closely.

'One of the striking features of these data is how much of the genetic variation that influences diabetes is shared between major ethnic groups,' says Wellcome Trust Senior Investigator Professor Mark McCarthy from the University of Oxford. 'This has allowed us to combine data from more than 50 studies from across the globe to discover new genetic regions affecting risk of diabetes.'

He adds: 'The overlap in signals between populations of European, Asian and Hispanic origin argues that the risk regions we have found to date do not explain the clear differences in the patterns of diabetes between those groups.'

Among the regions identified by the international research team are two, near the genes ARL15 and RREB1, that also show strong links to elevated levels of insulin and glucose in the body two key characteristics of type 2 diabetes. This finding provides insights into the ways basic biochemical processes are involved in the risk of type 2 diabetes, the scientists say.

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Seven new genetic regions linked to type 2 diabetes