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Researchers Find Genetic Regions Associated with Depression

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Depression is one of the most common mental health conditions in the world. In 2014 alone, an estimated 15.7 million American adults reported having at least one depressive episode. Scientists have been saying for decades that depression is a real illness with multiple physiological causes, yet we tend to treat it like it’s a shameful character flaw or a choice. A new study puts another nail in the coffin of that harmful fallacy: Researchers have identified 15 areas of the genome that are significantly more common in people with major depressive disorder (MDD). They published their findings today in the journal Nature Genetics.

MDD, also known as clinical depression, can turn lives upside down. People with depression are not "just sad"; they’re facing down symptoms like fatigue, loss of appetite, physical pain, feelings of hopelessness, and trouble concentrating. Depression can make it very hard to work or engage with loved ones.

The good news is that treatments are available. The bad news is that everyone’s depression is different, and finding the right treatment can take time. Researchers are hard at work learning everything they can about the causes and physiology of depression, because the more we know, the more effective our treatments can become.

We’ve known for a while that depression tends to run in families, but the details of that genetic component have largely remained elusive. One previous study of more than 10,000 Chinese women had already looked into, and found, genetic regions associated with depression, and researchers wanted to know if they might be able to find similar traces in other people.

Fortunately, we’re living in an age of crowd sourcing and quantified everything, when getting your DNA tested is as simple as mailing off a swab covered with your saliva. Millions of people are submitting their samples to testing companies like 23andMe, and many of them have agreed to make their results available to researchers. So the team pulled genetic data on more than 300,000 23andMe users of European descent. Of those volunteers, 75,607 said they’d been diagnosed with or treated for clinical depression.

The researchers then scanned all the participants’ genomes, looking for potential areas of overlap. They found them: 17 genetic variations—specifically, single nucleotide polymorphisms, or SNPs—spread through 15 regions of the DNA of people with depression. Further analysis showed that those 15 regions are hotspots for genes expressed in the nervous system and those associated with brain development. And previous studies have already linked those regions to other mental health issues.

Like its predecessor, this study looked at one specific group of people of similar descent, most of whom were women (62 percent). So while the results are not universal, they nevertheless underscore the crucial role of genetics in mental health.

Roy Perlis is a medical director at the Department of Psychiatry and the Center for Human Genetic Research at Massachusetts General Hospital, as well as co-corresponding author on the paper.

"Identifying genes that affect risk for a disease is a first step toward understanding the disease biology itself, which gives us targets to aim for in developing new treatments," Perlis said in a press statement. "More generally, finding genes associated with depression should help make clear that this is a brain disease, which we hope will decrease the stigma still associated with these kinds of illnesses."

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Gino Fornaciari, University Of Pisa
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Stones, Bones, and Wrecks
Scientists Accidentally Discover Ancient Hepatitis B in a 16th-Century Mummy
Gino Fornaciari, University Of Pisa
Gino Fornaciari, University Of Pisa

Since the 1980s, a child mummy buried in the Basilica of Saint Domenico Maggiore in Naples, Italy in the 16th century has been known as the earliest recorded case of smallpox in the world. The problem is, the 2-year-old didn’t have smallpox, according to new research spotted by IFLScience. But, as the scientists reexamining the remains discovered, it’s still a landmark study in disease evolution. It appears to be the earliest instance of hepatitis B that researchers have ever found in Italy, giving scientists insight into how the virus has evolved over the last several centuries.

The hepatitis B virus (HBV) attacks the liver and can result in cirrhosis and liver cancer, killing around 887,000 people per year. Though it can now be largely prevented by a vaccine, the World Health Organization estimates that 257 million people around the world live with HBV. It often affects children, spreading from mother to child during birth.

For the current study published in PLOS Pathogens, a team of researchers from McMaster University in Canada set about studying the child mummy with the hopes of continuing their past work nailing down how smallpox spread and evolved over human history. But when they used molecular analysis to study the mummy’s skin and bones, they didn’t find anything that indicated that the toddler had smallpox. Instead, they found the hepatitis B virus—which can cause a rash called Gianotti-Crosti Syndrome that the original researchers studying the mummy may have mistaken for the telltale rash associated with smallpox.

The ancient HBV strain found in the mummy's tissues had a genome closely related to that of the modern virus, which, The New York Times explains, could very well mean that the mummy was contaminated when it was first studied in the 1980s. But after analyzing the genetic material further and studying other examples of older HBV strains, they found that it’s plausible that the virus just hasn’t evolved extensively in the past 500 years. Though the contamination theory is still possible, it’s more likely that the mummy really does carry an ancient version of the virus. Considering that HBV has also been traced back to the 16th century in Asia, it’s likely that Europeans were suffering from it around the same time.

[h/t IFLScience]

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Illustration by Eric S. Carlson in collaboration with Ben A. Potter
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Stones, Bones, and Wrecks
11,500-Year-Old Skeleton Reveals an Unknown Group of Ancient Migrants to the Americas
Illustration by Eric S. Carlson in collaboration with Ben A. Potter
Illustration by Eric S. Carlson in collaboration with Ben A. Potter

In 2013, deep in the forest of central Alaska's remote Tanana River Valley, archaeologists unearthed the remains of a 6-week-old baby at a Late Pleistocene archaeological site. The tiny bones yielded big surprises for researchers, who announced this week that the child's genome—the oldest complete genetic profile of a New World human—reveals the existence of a human lineage that was previously unknown to scientists. Related to yet genetically distinct from modern Native Americans, the infant offers fresh insights into how the Americas were first peopled, National Geographic reports.

Published in the journal Nature on January 3, the study analyzed the DNA of the infant, whom the local Indigenous community named Xach'itee'aanenh T'eede Gaay ("sunrise girl-child" in the local Athabascan language). Then, researchers used genetic analysis and demographic modeling to identify connections between different groups of ancient Americans. This allowed them to figure out where this newly identified population—named Ancient Beringians—fit on the timeline.

University of Alaska Fairbanks professors Ben Potter and Josh Reuther excavate at the Upward Sun River site in central Alaska.
Members of the archaeology field team watch as University of Alaska Fairbanks professors Ben Potter and Josh Reuther excavate at the Upward Sun River site.
UAF photo courtesy of Ben Potter

The study suggests that a single founding group of Native Americans separated from East Asians some 35,000 years ago. This group, in turn, ended up dividing into two distinct sub-groups 15,000 years later, consisting of both the Ancient Beringians and what would eventually become the distant ancestors of all other Native Americans. The division could have occurred either before or after humans crossed over the Bering land bridge around 15,700 years ago.

After arriving in the New World, Ancient Beringians likely remained north, while the other population spread out across the continent. Eventually, the Ancient Beringians either melded with or were replaced by the Athabascan peoples of interior Alaska. 

The study provides "the first direct evidence of the initial founding Native American population, which sheds new light on how these early populations were migrating and settling throughout North America," said Ben Potter, the University of Alaska-Fairbanks archaeologist who discovered the remains, in a news release. Potter was a lead author of the study, along with Eske Willerslev and other researchers at the Center for GeoGenetics at the University of Copenhagen's Natural History Museum of Denmark.

[h/t National Geographic]

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