'Genetically Speaking' series showcases research findings, technological advances, and applications of human genetics in the evaluation, diagnosis, and treatment of health conditions

BETHESDA, MD and Fort Washington, PA - The American Society of Human Genetics (ASHG) and ReachMD announced today the launch of 'Genetically Speaking', a series of audio interviews designed to educate healthcare professionals on the application of human genetics in disease prevention and management.

The series features peer-to-peer interviews conducted during the ASHG 2014 Annual Meeting and includes topics such as:

"One of our primary goals at ASHG is to develop a healthcare workforce that is genetics-literate and capable of interpreting and applying information in clinical practice," said Joseph D. McInerney, MA, MS, Executive Vice President of ASHG. "We are excited to team up with ReachMD to produce and deliver peer-to-peer programming to healthcare professionals nationwide."

'Genetically Speaking' is co-produced by ASHG and ReachMD and broadcast on ReachMD's integrated online, mobile, and on air content distribution network. Content is accessible both on demand and through 24/7 radio streaming on ReachMD, iHeartRadio, TuneIn, and iTunes digital platforms.

"This series is an excellent addition to the ReachMD lineup," said Matt Birnholz, MD, Vice President and Medical Director of ReachMD. "Our users love cutting-edge programming, and the scientific and medical experts on this series really showcase the latest research and the applications of genetics in disease prevention and management."

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Link to 'Genetically Speaking': https://reachmd.com/programs/genetically-speaking/

Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.

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ASHG and ReachMD launch educational series on genetics and genomics

Genetics research sheds light on a long human relationship

A poison we adapted to tolerate

Credit: Thinkstock

Alcohol has been part of human existence for millennia. Alcoholic beverages are an integral part of human culture. Like the wines consumed in Jewish and Christian rituals, these drinks have ceremonial and religious uses. Until the nineteenth century, beer, brandy, rum or grog was the drink of choice for sailors in lieu of stagnant water during long voyages. Alcohol is a social lubricant, an anesthetic and an antiseptic. It is one of the most widely used drugs in the world and has been manufactured since the advent of agriculture nearly 9000 years ago. How is it that this drug an intoxicating poison has become such a part of human existence?

A new study finds that our forebears acquired the capacity to digest alcohol some 10 million years ago, among a common ancestor to humans, chimpanzees and gorillas, and certainly well before we learned to manufacture it. This suggests that alcohol became part of the human diet much earlier than previously thought, and in a manner that had significant implications for the survival of the human species.

Humans carry with them genetic signatures of their ancestral feeding habits. Genetic variants that make new food sources available can provide tremendous opportunities to those who possess them. The ability to consume milk, for example, is due to the lactase persistence variant of a gene which emerged around 7500 years ago among early Europeans. For those lacking the mutation, the lactose in milk is a mild poison, eliciting symptoms akin to those of dysentery. Similarly, the ability to digest alcohol may be a genetic signature of feeding pattern among human ancestors: this alcohol tolerance may have made it possible to eat over-ripe fruit that had fallen to the ground and begun to naturally ferment. Since few animals can tolerate alcohol, this would have provided our ancestors with an abundant food source for which there were few competitors. It may also have contributed to the move towards a terrestrial rather than arboreal existence.

The breakdown of alcohol after ingestion is a complex process that involves a number of different enzymes. Most of the alcohol that is ingested is broken down in the gut and liver. This study focused on the enzyme ADH4 because it is abundant in the gut and plays a major role in preventing ingested alcohol from entering the blood stream. ADH4 from human relatives as distant as the tree shrew were tested for their ability to digest alcohol. The form of ADH4 found in humans, gorillas and chimpanzees was found to be 40 fold more efficient at clearing alcohol than the form found in more primitive species. ADH4 also digests chemicals that plants produce in order to deter animals from feeding upon them. However, with the increase in ability to digest alcohol came a reduced ability to digest many of these other chemicals. This suggests that the food containing alcohol was more important.

While ADH4 is among the most important enzymes for the digestion of alcohol, it is not the only one. Another related enzyme, ADH3, also contributes to the breakdown of alcohol. Women typically have lower activity levels of this enzyme, leading them to have higher blood levels of alcohol then men after taking a high dose of alcohol. And ADH4 is not the only enzyme that may have helped humans adapt to the consumption of alcohol: a variant of a liver enzyme (ADH1B) with high activity in the breakdown of alcohol emerged among East Asian populations during the advent of rice cultivation, perhaps as an adaptation to rice fermentation. (Interestingly, other animals have adopted their own strategies: Using a different enzyme, a member of the tree shrew family is able to consume fermented nectar from palm tree flowers the equivalent of 10 -12 glasses of wine every day without obvious signs of intoxication.)

Because humans rely upon ADH4 as their primary means to digest alcohol, they are also susceptible to hangovers. ADH4 and similar enzymes digest alcohol by converting it into another chemical, acetaldehyde, which causes the skin flushing, headache and other symptoms of overindulgence. The modern consumption of alcohol has been characterized as an "evolutionary hangover," an adaptation to modest levels of alcohol in food sources which left humans prone to alcohol abuse once we learned how to manufacture it in highly concentrated forms. And, in fact, genetic variants of ADH4 have been linked to alcohol and drug dependence, although there are many other genes that may influence susceptibility to alcohol dependency. Regardless of the role ADH4 plays in alcohol addiction, its clear that our complex relationship with alcohol dates back millions of year, and began, in fact, before we were even human.

Robert Martone is a researcher working on neuro-oncology biomarker discovery and development. He lives and works in Memphis TN.

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Our Taste for Alcohol Goes Back Millions of Years

The newly identified gene is found in modern-day humans, Neandertals and Denisovans, but not in chimps

New research suggests that a single gene may be responsible for the large number of neurons found uniquely in the human brain. When this gene was inserted in the brain of a mouse embryo (shown here), it induced the formation of many more neurons (stained red). The extra neurons led to the formation of characteristic convolutions that the human brain uses to pack so much brain tissue into a small space (convolutions shown on the right). Credit: Marta Florio and Wieland B. Huttner, Max Planck Institute of Molecular Cell Biology and Genetics

A single gene may have paved the way for the rise of human intelligence by dramatically increasing the number of brain cells found in a key brain region.

This gene seems to be uniquely human: It is found in modern-day humans, Neanderthals and another branch of extinct humans called Denisovans, but not in chimpanzees.

By allowing the brain region called the neocortex to contain many more neurons, the tiny snippet of DNA may have laid the foundation for the human brain's massive expansion.

"It is so cool that one tiny gene alone may suffice to affect the phenotype of the stem cells, which contributed the most to the expansion of the neocortex," said study lead author Marta Florio, a doctoral candidate in molecular and cellular biology and genetics at the Max Planck Institute of Molecular Cell Biology and Genetics in Dresden, Germany. Still, it's likely this gene is just one of many genetic changes that make human cognition special, Florio said.

An expanding brain

The evolution from primitive apes to humans with complex language and culture has taken millions of years. Some 3.8 million ago, Australopithecus afarensis, the species typified by the iconic early human ancestor fossil Lucy, had a brain that was less than 30 cubic inches (500 cubic centimeters) in volume, or about a third the size of the modern human brain. By about 1.8 million years ago, Homo erectus was equipped with a brain that was roughly twice as big as that of Australopithecus. H. erectus also showed evidence of tool and fire use and more complex social groups.

Once anatomically modern humans, and their lost cousins the Neanderthals and Denisovans, arrived on the scene, the brain had expanded to roughly 85 cubic inches (1.4 liters) in volume. Most of this growth occurred in a brain region called the neocortex.

"The neocortex is so interesting because that's the seat of cognitive abilities, which, in a way, make us human like language and logical thinking," Florio told Live Science.

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"Big Brain" Gene Allowed for Evolutionary Expansion of Human Neocortex

Thousands of genetic "dimmer" switches, regions of DNA known as regulatory elements, were turned up high during human evolution in the developing cerebral cortex, according to new research from the Yale School of Medicine.

Unlike in rhesus monkeys and mice, these switches show increased activity in humans, where they may drive the expression of genes in the cerebral cortex, the region of the brain that is involved in conscious thought and language. This difference may explain why the structure and function of that part of the brain is so unique in humans compared to other mammals.

The research, led by James P. Noonan, Steven K. Reilly, and Jun Yin, is published March 6 in the journal Science.

In addition to creating a rich and detailed catalogue of human-specific changes in gene regulation, Noonan and his colleagues pinpointed several biological processes potentially guided by these regulatory elements that are crucial to human brain development.

"Building a more complex cortex likely involves several things: making more cells, modifying the functions of cortical areas, and changing the connections neurons make with each other. And the regulatory changes we found in humans are associated with those processes," said Noonan, associate professor of genetics, an investigator with the Kavli Institute for Neuroscience, and senior author of the study. "This likely involves evolutionary modifications to cellular proliferation, cortical patterning, and other developmental processes that are generally well conserved across many species."

Scientists have become adept at comparing the genomes of different species to identify the DNA sequence changes that underlie those differences. But many human genes are very similar to those of other primates, which suggests that changes in the way genes are regulated -- in addition to changes in the genes themselves -- is what sets human biology apart.

Up to this point, however, it has been very challenging to measure those changes and figure out their impact, especially in the developing brain. The Yale researchers took advantage of new experimental and computational tools to identify active regulatory elements -- those DNA sequences that switch genes on or off at specific times and in specific cell types -- directly in the human cortex and to study their biological effects.

First, Noonan and his colleagues mapped active regulatory elements in the human genome during the first 12 weeks of cortical development by searching for specific biochemical, or "epigenetic" modifications. They did the same in the developing brains of rhesus monkeys and mice, then compared the three maps to identify those elements that showed greater activity in the developing human brain. They found several thousand regulatory elements that showed increased activity in human.

Next, they wanted to know the biological impact of those regulatory changes. The team turned to BrainSpan, a freely available digital atlas of gene expression in the brain throughout the human lifespan. (BrainSpan was led by Kavli Institute member Nenad Sestan at Yale, with contributions from Noonan and Pasko Rakic, a co-author on this study.) They used those data to identify groups of genes that showed coordinated expression in the cerebral cortex. They then overlaid the regulatory changes they had found with these groups of genes and identified several biological processes associated with a surprisingly high number of regulatory changes in humans.

"While we often think of the human brain as a highly innovative structure, it's been surprising that so many of these regulatory elements seem to play a role in ancient processes important for building the cortex in all mammals, said first author Steven Reilly. "However, this is often a hallmark of evolution, tinkering with the tools available to produce new features and functions."

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Yale researchers map 'switches' that shaped the evolution of the human brain