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Man Is His Own Child’s Uncle, Says DNA Testing

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A baby boy born in Washington last year is his own cousin, geneticists found. The child’s father is a genetic chimera—a person who carries two sets of DNA. After failing several paternity tests, the man learned that “his” sperm actually belonged to a twin he had absorbed in the womb. The vanished twin, therefore, was technically the baby’s father [PDF].

Most people with chimerism will never find out. The process of absorption takes place so early in fetal development that there are rarely outward signs. Two eggs become one, and normally no one is the wiser. Sometimes a chimeric person will have two differently colored eyes. In cases when one egg is male and one is female, the resulting baby may be intersex, but even that presents in varying degrees of obviousness. The skin of some people with chimerism may even be striped or swirled where the two lines of DNA met, but again, this is rare. 

This isn’t the first case of its kind, although it is the first to focus on a father. Karen Keegan and Lydia Fairchild were the subjects of intense scrutiny after DNA tests showed that they couldn’t possibly be the mothers of their own children. Fairchild was accused of kidnapping and nearly lost her case. Only when doctors read about Keegan’s case did they consider the possibility that Fairchild might be a chimera. Genetic testing bore out the theory, and Fairchild got to keep her kids.

The parents in the most recent case first suspected something was up when their son was born, reports BuzzFeed's Dan Vergano. He was healthy, but his blood type didn’t match his father’s or his mother’s. A cheek-swab paternity test confirmed that the child’s DNA did not match his father’s. The couple, who had conceived through in vitro fertilization, worried that their fertility clinic had used a stranger’s sperm by accident.

They checked with the clinic. Staff assured them that there had been no mix-up. So whose sperm was it, exactly? The couple took their question to Stanford University geneticist Barry Starr, who runs the Ask a Geneticist website. Starr suggested a more comprehensive type of genetic testing. Those results showed that the baby was definitely related to his father—both as a nephew and a son.

But the man had no brother … not that he knew of, anyway. He did, however, have striped skin.

More tests confirmed Starr’s suspicion that the man was indeed a chimera.

As genetic testing becomes both more advanced and more commercially available, incidents like this may become common. The rise in fertility treatments will likely also contribute to the incidence of chimerism itself, since those procedures often lead to multiple births, or at least multiple fertilized eggs. For obvious reasons, scientists aren’t sure how many of us are chimeras. Only time will tell.

[h/t Buzzfeed

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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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