CLOSE
ISTOCK
ISTOCK

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

ISTOCK
ISTOCK

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

nextArticle.image_alt|e
Courtesy of Nature
arrow
science
Scientists Create Three Puppy Clones of 'Snuppy,' the World's First Cloned Dog
Courtesy of Nature
Courtesy of Nature

Snuppy, the world's first cloned dog, died in 2015, but his genetic legacy lives on. As the National Post reports, South Korean scientists recently described in the journal Scientific Reports the birth of three clone puppies, all of which are identical replicas of the famous Afghan hound.

Those who lived through the 1990s might remember Dolly, the Scottish sheep that gained fame for being the very first mammal to be cloned from an adult cell. Following Dolly's 1996 cloning, scientists managed to replicate other animals, including cats, mice, cows, and horses. But dog cloning initially stymied scientists, Time reports, as their breeding period is limited and their eggs are also hard to extract.

Ultimately, researchers ended up using somatic cell nuclear transfer (SCNT) to clone a dog, the same method that was used to make Dolly. In the early 2000s, a team of South Korean scientists inserted DNA harvested from an Afghan hound's skin cells into a dog egg from which the DNA had been removed. The egg divided, which produced multiple cloned embryos.

The scientists implanted 1095 of these embryos in 123 dogs, an exhaustive initiative that yielded just three pregnancies, according to NPR. Of these, Snuppy—whose name is a combination of "puppy" and Seoul National University's initials—was the only survivor.

Snuppy died from cancer in April 2015, just shortly after his 10th birthday. To celebrate his successful life, the same South Korean researchers decided to re-clone him using mesenchymal stem cells from the dog's belly fat, which were taken when he was five. This time around, they transferred 94 reconstructed embryos to seven dogs. Four clones were later born, although one ended up dying shortly after birth.

The tiny Snuppy clones are now more than a year old, and researchers say that they don't think that the pups face the risk of accelerated aging, nor are they more disease-prone than other dogs. (Dolly died when she was just six years old, while cloned mice have also experienced shorter lifespans.) Snuppy's somatic cell donor, Tai, lived just two years longer than Snuppy, dying at age 12, the average lifespan of an Afghan hound.

Researchers say that this new generation of Snuppys will yield new insights into the health and longevity of cloned animals. Meanwhile, in other animal cloning news, a Texas-based company called ViaGen Pets is now offering to clone people's beloved pets, according to CBS Pittsburgh—a service that costs a cool $50,000 for dogs.

[h/t National Post]

nextArticle.image_alt|e
iStock
arrow
Food
Researchers Pinpoint the Genes Behind the Durian's Foul Stench
iStock
iStock

Durian is a popular fruit in parts of southeast Asia. It's also known for having the most putrid, off-putting odor of any item sold in the produce section. Even fans of durian know why the fruit gets a bad rap, but what exactly causes its divisive scent is less obvious. Determined to find the answer, a team of researchers funded by "a group of anonymous durian lovers" mapped the fruit's genome, as reported by the BBC.

The study, published in the journal Nature Genetics [PDF], contains data from the first-ever complete genetic mapping of a durian fruit. It confirms that durian's excess stinkiness comes from sulfur, a chemical element whose scent is often compared to that of rotten eggs.

Analysis of the fruit's chemical makeup has been done in the past, so the idea that sulfur is a major contributor to its signature smell is nothing new. What is new is the identification of the specific class of sulfur-producing genes. These genes pump out sulfur at a "turbocharged" rate, which explains why the stench is powerful enough to have durian banned in some public areas. It may seem like the smell is a defense mechanism to ward off predators, but the study authors write that it's meant to have the opposite effect. According to the paper, "it is possible that linking odor and ripening may provide an evolutionary advantage for durian in facilitating fruit dispersal." In other words, the scent attracts hungry primates that help spread the seeds of ripe durian fruits by consuming them.

The revelation opens the door to genetically modified durian that are tweaked to produce less sulfur and therefore have a milder taste and smell. But such a product would likely inspire outrage from the food's passionate fans. While the flavor profile has been compared to rotten garbage and dead animal meat, it's also been praised for its "overtones of hazelnut, apricot, caramelized banana, and egg custard" by those who appreciate its unique character.

[h/t BBC]

SECTIONS

arrow
LIVE SMARTER
More from mental floss studios