13 Things to Know About DNA Testing Kits

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The search for our identities—where we came from, what we're made of—is a unifying human experience, and our collective fascination with ourselves as individuals has fueled a booming industry around personal DNA testing. More than 12 million people have had their DNA tested by services like 23andMe and AncestryDNA, and that number is expected to grow substantially in the next few years. But can DNA tests really reveal the nuanced information about ancestry and health that many of us seek? Here are 13 things to know about these personal testing kits.

1. PERSONAL DNA TESTING IS SIMPLE—ALL IT TAKES IS A LITTLE SPIT.

Typically, all you have to do is collect some of your saliva or swab the inside of your cheek, then seal the sample in a container and mail it to the lab in a pre-labeled envelope or box. Six to eight weeks later, you can see the results online.

Most personal DNA tests are relatively affordable: Kits from industry leaders like 23andMe, AncestryDNA, Family Tree DNA, MyHeritage DNA, and Living DNA range from $69 to $199. In some cases, the price depends on which genetic reports a customer opts to receive: For 23andMe, for instance, a test that only aims to analyze your ancestry is cheaper than one that also includes health information. Check out this Wiki chart from the International Society of Genetic Genealogy to compare companies' offerings.

2. THE KITS LOOK FOR GENETIC VARIATIONS CALLED SINGLE NUCLEOTIDE POLYMORPHISMS.

After extracting DNA from your cheek swab or saliva sample, DNA testing companies search your DNA for certain genetic variants. The building blocks of DNA are chemical bases called nucleotides, which come in four varieties—A, T, C, and G (adenine, thymine, cytosine, and guanine, respectively). We have 3 billion pairs of these bases, so 6 billion letters in all, strung together in a sequence. Altogether, this genetic information is called your genome.

DNA testing companies determine which of the four letters is present at many locations in your genome. Much of the sequence is shared among humans, so the companies focus on specific letters that vary from person to person, known as single nucleotide polymorphisms (SNPs). Many SNPs have some biological relevance. For example, having one variant of a specific SNP near the gene OCA2, which codes for a protein believed to be involved in producing the dark pigment melanin, makes it much more likely you’ll have blue or green eyes. Other traits and even some diseases are also associated with certain SNPs, some more strongly than others.

3. KIT ACCURACY CAN VARY BASED ON TESTING METHODS.

According to company spokesperson Scott Hadly, 23andMe can identify SNPs with 99.9 percent accuracy, which is in a plausible range for the methods they use. Since many other major companies use similar techniques, their accuracy may be about equivalent—but not all tests meet the same standards. Recently, one test failed to recognize that a purportedly human DNA sample actually came from a golden retriever named Bailey. It did recommend, though, that based on her genetics, Bailey should take up cycling and basketball. The canine’s results came from the lighthearted Superhero DNA Test, which claims to tell customers about their strength, speed, and intelligence. It only tests for four genetic variants, while the pricier kits can include tens of thousands of variants. (It's also worth noting that no matter how many variants a kit tests for, it can't predict complex traits like intelligence, which are influenced by many different genes and environmental factors.)

You should steer clear of companies that offer dubious predictions about your optimal diet, what sports you'll be good at, and other questionable tips. Experts say using DNA tests to extrapolate this information is at best premature and at worst pseudoscience, especially because the recommendations are often based on just a handful of studies on specific groups of people, commonly white men. "The results that have been acquired in one population are not always generalizable to other populations," Jason Rosenbaum, an assistant professor at the University of Pennsylvania's medical school, tells Mental Floss.

4. DNA CAN REVEAL GENETIC CONNECTIONS—BUT INFORMATION ON SOME POPULATIONS IS LIMITED.

Companies use various methods to determine ancestry, but the tests generally involve comparing the customer's DNA to reference DNA meant to represent populations from different geographical regions. Since most people have at least somewhat mixed heritage, ancestry is often represented in percentages: 26 percent Polish, 14 percent Greek, and so on.

These tests aren’t able to guarantee where your ancestors actually lived—they can’t directly compare your data to DNA from people who lived hundreds of years ago, as Adam Rutherford, a British geneticist, pointed out to Gizmodo. And not all groups of people are equally represented in the reference populations, which can impact how precise your results are. People with European backgrounds are overrepresented in the reference data, while there are fewer references relevant to those whose roots lie in the Middle East or Asia, for example. But as research is done on a more diverse range of people, companies are tweaking their analyses to provide more detailed ancestry information to people from all over the world.

5. SOME HINT AT YOUR DNA'S DISTANT HISTORY—INCLUDING NEANDERTHAL HERITAGE.

All humans alive today can trace their mitochondrial lineage back to one woman nicknamed Mitochondrial Eve, who may have lived in Africa about 150,000–200,000 years ago (although this is a source of perennial debate). She wasn't the first modern human woman or the only woman living at the time; other women from her time also have descendants today. They just don’t have an unbroken line of female descendants like Mitochondrial Eve does.

We inherit our mitochondria—the parts of our cells that make energy—from our mothers. Some companies offer a mitochondrial DNA test that allows you to find your maternal haplogroup, which includes people who all share a maternal ancestor thousands or tens of thousands of years ago.

Men can learn about their paternal line through the Y chromosome, which is passed from father to son; certain SNPs on the Y chromosome can be used to determine a person's paternal haplogroup. (Women can find their paternal haplogroup through their biological father or brother.) There’s a "Y-chromosomal Adam," too, although scientists disagree about whether he lived around the same time as Mitochondrial Eve.

A home DNA test might even tell you that you're a little bit Neanderthal, which is especially common in Caucasian and Asian people. Don't worry about Neanderthals' reputation as dull brutes. We now know they were intelligent, used tools, and had their own complex culture.

6. YOU COULD FIND RELATIVES YOU DIDN'T KNOW YOU HAD.

Many DNA testing services allow customers to see whether other users of the same service are biologically related. This can be a boon for anyone assembling a detailed family tree, as well as any adoptees wondering about their biological families. Several people have discovered siblings they never knew they had through these services. In one case, two women—one adopted through an agency and another adopted by a family who found her in the woods as a baby—realized they were long-lost sisters.

Not everyone is pleased to uncover family secrets, though, and you should proceed with caution before you allow a company to match you with new relatives.

7. DNA TESTS CAN REVEAL HEALTH INFORMATION …

While genetic testing might reveal your inability to detect the unique odor of asparagus pee, most people are seeking deeper information, such as whether they have genetic variants associated with diseases like Alzheimer's or breast cancer.

Genetic risk is all about probability. For example, it may be frightening to learn you have an SNP associated with a tenfold increase in risk for a disease—but if that disease only affects 0.01 percent of people, your risk is still just 0.1 percent. Even if you have a SNP strongly associated with a more common illness and show signs of having it, you should see a doctor to get a proper evaluation.

And having a disease-associated SNP isn't a diagnosis. Rare variants are especially likely to lead to false positives: if a variant is only found in one in a million people, it’s more likely that the positive test result is an error than it would be with a more common variant. Some companies report on genetic variants that doctors and scientists haven't deemed medically useful to test for—which is why combing over every SNP is of dubious use. Shoumita Dasgupta, an associate professor in the biomedical genetics program at Boston University, tells Mental Floss that healthcare providers often don't order tests for these SNPs "because professionals have come to the conclusion that the predictive value of these tests is limited."

8. … INCLUDING YOUR RISK OF CERTAIN KINDS OF CANCER.

In March 2018, the FDA granted 23andMe permission to give customers information about certain mutations in the genes BRCA1 and BRCA2 that dramatically increase the risk for breast and ovarian cancer. Some people with a faulty BRCA gene take precautions to prevent or detect cancer early, including undergoing preventive double mastectomies, as Angelina Jolie famously did in 2013.

An important caveat: This test only screens for three SNPs in the BRCA genes that are connected to a dramatic increase in the risk of developing cancer. A positive result merits a consultation with doctor, but a negative result doesn't necessarily mean you're free from the risk of cancer, hereditary or not.

9. SOME DNA TESTING KITS ARE PRESCRIPTION ONLY.

GeneSight is designed to reveal what psychiatric medications will work best for a particular patient. Fertilome aims to show whether a person has genetic markers associated with increased risk of fertility problems, and is intended to help people make reproductive decisions such as whether to freeze eggs or try another round of in vitro fertilization. However, both Fertilome and GeneSight have faced criticism from experts who say there's not enough evidence that the tests are clinically valuable. They're also expensive: Fertilome costs $950, while GeneSight can cost several hundred dollars (though the price can drop to zero with certain insurance plans).

10. MORE DATA ISN'T ALWAYS BETTER.

With the price of DNA analysis falling rapidly, some companies are offering to analyze the order of all the letters of a customer's DNA—what's called sequencing—rather than just looking at SNPs. Sequencing is important in research and medicine: Dasgupta says she now sees some physicians ordering full sequences of multiple genes or even whole exomes (the protein-coding sequences in the genome) for patients.

Exome sequencing is useful to doctors and scientists because it allows them to look for genetic variants beyond the commonly tested SNPs. But every test has a risk of generating false positives, so excessive testing means an increased risk that a person will receive an incorrect diagnosis. Rosenbaum likens it to MRIs. "It's one reason why we don't just give MRIs to everyone, because you're going to turn up things that lead you to believe there's disease where there isn't disease," he explains.

11. YOUR DNA RESULTS COULD CONTRIBUTE TO RESEARCH.

Some home DNA testing companies ask customers to participate in research, answering questions about everything from their sleep habits to their personalities. The goal is to discover previously unknown associations between genetic variants and specific traits. "The way many genetic studies are designed, the more people who are recruited to the study, the more likely the study will be able to identify genetic factors that impact the trait or condition being studied," Dasgupta says.

Personal DNA testing companies potentially have access to the genetic data of millions of users, giving them a huge opportunity to make these connections. Using customer-provided data, 23andMe has already reported some preliminary discoveries on genetic variants linked to detached earlobes, the risk of Parkinson's disease, and more. Studies based on self-reported information always come with caveats, but they’re common in many fields of research and especially useful when collecting objective data isn't practical or possible. Future research spurred by these observations will reveal whether crowdsourced research like 23andMe's has potential to become part of geneticists' repertoire.

12. YOU COULD POTENTIALLY EARN MONEY FROM YOUR DNA.

One company, Genos, charges $499 to sequence a customer's entire exome, and then offers to connect them with genetic researchers. Participating research partners can offer $50 to $250 to Genos users for completing a study intended to find links between their genetic information and any trait or condition the researchers are studying, including dementia, cancer, and infectious disease. Meanwhile, the newly formed company Nebula proposes to sequence customers' genomes, secure them with blockchain technology, and allow customers to control the data—including selling it to biotech and pharmaceutical companies in exchange for Bitcoin-like cryptocurrency. There’s still potential for privacy issues, however, since there’s no guarantee companies that rent or purchase genetic data will keep it secure.

13. YOUR DNA MIGHT ONE DAY HELP TO CATCH A CRIMINAL.

Recently, police investigators in California arrested a man suspected to be the Golden State Killer, thought to be responsible for dozens of rapes and burglaries and at least 12 murders in California from 1976 to 1986. The suspect left DNA behind at the scene of a 1980 murder; after having the DNA analyzed, the investigators created a fake profile on the genealogy website GEDMatch and uploaded the data, hoping it would turn up some of the killer's relatives. It did—and with the help of genealogy experts, the investigators followed the genetic trail to the Sacramento home of 72-year-old Joseph James DeAngelo, who was a cop during the first several years of the deadly crime spree.

The case has raised ethical and privacy concerns for some experts. Genetic data can be stored indefinitely, and it’s possible to use a person's DNA to make inferences about biological relatives who haven’t even taken DNA tests.

15 Gripping Facts About Galileo

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Getty Images

Albert Einstein once said that the work of Galileo Galilei “marks the real beginning of physics.” And astronomy, too: Galileo was the first to aim a telescope at the night sky, and his discoveries changed our picture of the cosmos. Here are 15 things that you might not know about the father of modern science, who was born February 15, 1564.

1. There's a reason why Galileo Galilei's first name echoes his last name.

You may have noticed that Galileo Galilei’s given name is a virtual carbon-copy of his family name. In her book Galileo’s Daughter, Dava Sobel explains that in Galileo’s native Tuscany, it was customary to give the first-born son a Christian name based on the family name (in this case, Galilei). Over the years, the first name won out, and we’ve come to remember the scientist simply as “Galileo.”

2. Galileo Galilei probably never dropped anything off the leaning tower of Pisa. 

With its convenient “tilt,” the famous tower in Pisa, where Galileo spent the early part of his career, would have been the perfect place to test his theories of motion, and of falling bodies in particular. Did Galileo drop objects of different weights, to see which would strike the ground first? Unfortunately, we have only one written account of Galileo performing such an experiment, written many years later. Historians suspect that if Galileo taken part in such a grand spectacle, there would be more documentation. (However, physicist Steve Shore did perform the experiment at the tower in 2009; I videotaped it and put the results on YouTube.)

3. Galileo taught his students how to cast horoscopes.

It’s awkward to think of the father of modern science mucking about with astrology. But we should keep two things in mind: First, as historians remind us, it’s problematic to judge past events by today’s standards. We know that astrology is bunk, but in Galileo’s time, astrology was only just beginning to disentangle from astronomy. Besides, Galileo wasn’t rich: A professor who could teach astrological methods would be in greater demand than one who couldn’t.

4. Galileo didn't like being told what to do.

Maybe you already knew that, based on his eventual kerfuffle with the Roman Catholic Church. But even as a young professor at the University of Pisa, Galileo had a reputation for rocking the boat. The university’s rules demanded that he wear his formal robes at all times. He refused—he thought it was pretentious and considered the bulky gown a nuisance. So the university docked his pay.

5. Galileo Galilei didn't invent the telescope.

We’re not sure who did, although a Dutch spectacle-maker named Hans Lipperhey often gets the credit (he applied for a patent in the fall of 1608). Within a year, Galileo Galilei obtained one of these Dutch instruments and quickly improved the design. Soon, he had a telescope that could magnify 20 or even 30 times. As historian of science Owen Gingerich has put it, Galileo had managed “to turn a popular carnival toy into a scientific instrument.”

6. A king leaned on Galileo to name planets after him.

Galileo rose to fame in 1610 after discovering, among other things, that the planet Jupiter is accompanied by four little moons, never previously observed (and invisible without telescopic aid). Galileo dubbed them the “Medicean stars” after his patron, Cosimo II of the Medici family, who ruled over Tuscany. The news spread quickly; soon the king of France was asking Galileo if he might discover some more worlds and name them after him.

7. Galileo didn't have trouble with the church for the first two-thirds of his life.

In fact, the Vatican was keen on acquiring astronomical knowledge, because such data was vital for working out the dates of Easter and other holidays. In 1611, when Galileo visited Rome to show off his telescope to the Jesuit astronomers there, he was welcomed with open arms. The future Pope Urban VIII had one of Galileo’s essays read to him over dinner and even wrote a poem in praise of the scientist. It was only later, when a few disgruntled conservative professors began to speak out against Galileo, that things started to go downhill. It got even worse in 1616, when the Vatican officially denounced the heliocentric (sun-centered) system described by Copernicus, which all of Galileo’s observations seemed to support. And yet, the problem wasn’t Copernicanism. More vexing was the notion of a moving Earth, which seemed to contradict certain verses in the Bible.

8. Galileo probably could have earned a living as an artist.

We think of Galileo as a scientist, but his interests—and talents—straddled several disciplines. Galileo could draw and paint as well as many of his countrymen and was a master of perspective—a skill that no doubt helped him interpret the sights revealed by his telescope. His drawings of the Moon are particularly striking. As the art professor Samuel Edgerton has put it, Galileo’s work shows “the deft brushstrokes of a practiced watercolorist”; his images have “an attractive, soft, and luminescent quality.” Edgerton writes of Galileo’s “almost impressionistic technique” more than 250 years before Impressionism developed.

10. Galileo wrote about relativity long before Einstein.

He didn’t write about exactly the same sort of relativity that Einstein did. But Galileo understood very clearly that motion is relative—that is, that your perception of motion has to do with your own movement as well as that of the object you’re looking at. In fact, if you were locked inside a windowless cabin on a ship, you’d have no way of knowing if the ship was motionless, or moving at a steady speed. More than 250 years later, these ideas would be fodder for the mind of the young Einstein.

10. Galileo never married, but that doesn't mean he was alone.

Galileo was very close with a beautiful woman from Venice named Marina Gamba; together, they had two daughters and a son. And yet, they never married, nor even shared a home. Why not? As Dava Sobel notes, it was traditional for scholars in those days to remain single; perceived class difference may also have played a role.

11. You can listen to music composed by Galileo's dad.

Galileo’s father, Vincenzo, was a professional musician and music teacher. Several of his compositions have survived, and you can find modern recordings of them on CD (like this one). The young Galileo learned to play the lute by his father’s side; in time he became an accomplished musician in his own right. His music sense may have aided in his scientific work. With no precision clocks, Galileo was still able to time rolling and falling objects to within mere fractions of a second.

12. His discoveries may have influenced a scene in one of Shakespeare's late plays.

An amusing point of trivia is that Galileo and Shakespeare were born in the same year (1564). By the time Galileo aimed his telescope at the night sky, however, the English playwright was nearing the end of his career. But he wasn’t quite ready to put down the quill: His late play Cymbeline contains what may be an allusion to one of Galileo’s greatest discoveries—the four moons circling Jupiter. In the play’s final act, the god Jupiter descends from the heavens, and four ghosts dance around him in a circle. It could be a coincidence—or, as I suggest in my book The Science of Shakespeare, it could hint at the Bard's awareness of one of the great scientific discoveries of the time.

13. Galileo had some big-name visitors while under house arrest.

Charged with “vehement suspicion of heresy,” Galileo spent the final eight years of his life under house arrest in his villa outside of Florence. But he was able to keep writing and, apparently, to receive visitors, among them two famous Englishmen: the poet John Milton and the philosopher Thomas Hobbes.

14. Galileo's bones have not rested in peace.

When Galileo died in 1642, the Vatican refused to allow his remains to be buried alongside family members in Florence’s Santa Croce Basilica; instead, his bones were relegated to a side chapel. A century later, however, his reputation had improved, and his remains (minus a few fingers) were transferred to their present location, beneath a grand tomb in the basilica’s main chapel. Michelangelo is nearby.

15. Galileo might not have been thrilled with the Vatican's 1992 "apology."

In 1992, under Pope John Paul II, the Vatican issued an official statement admitting that it was wrong to have persecuted Galileo. But the statement seemed to place most of the blame on the clerks and theological advisers who worked on Galileo’s case—and not on Pope Urban VIII, who presided over the trial. Nor was the charge of heresy overturned.

Additional sources: The Discoveries and Opinions of Galileo; Galileo's Daughter; The Cambridge Companion to Galileo.

10 Things You Should Know About Asthma

iStock.com/Wojciech Kozielczyk
iStock.com/Wojciech Kozielczyk

To anyone with asthma, the feeling of an attack is unmistakable. Patients have compared an asthma attack's feeling of breathlessness, caused by inflammation in the lungs and airways, to being smothered by a pillow or having an elephant sit on their chest. Medical experts have already figured out some aspects of asthma, like how to diagnose and treat it, but other components, like what causes asthma and how to cure it, remain unclear. From the triggers people encounter at work to the connection to allergies, here are some facts about asthma symptoms and treatments you should know.

1. Asthma attacks are related to allergies.

The physical process that occurs when someone has a sneezing fit during pollen season is similar to what happens during an asthma attack. But while the former causes discomfort, the latter produces potentially life-threatening symptoms. When people with allergies are exposed to an allergen like pollen, they produce antibodies that bind to that allergen. This signals the body to release the chemicals that cause allergic symptoms. In most people, the symptoms are limited to the head, such as a runny nose or watery eyes, but in people with asthma, they're felt in the lungs. If the lungs are inflamed, the airways that carry air swell up and fill with mucus, constricting airflow and causing common asthma symptoms like coughing, wheezing, and shortness of breath. Such asthma attacks can be fatal when patients can’t get enough air to their lungs.

2. Asthma is the most prevalent chronic disease among children.

Asthma is common, affecting 25 million in the U.S. alone, and of those patients, about 7 million are children. Most people with the disease develop it during childhood. Asthma is the most prevalent chronic illness among kids, and each year, students miss 13.8 million school days because of it.

3. Asthma may be inherited.

Doctors aren’t entirely sure what causes asthma, but they know it sometimes runs in families. A 2010 study found that people with one parent with the condition were nearly twice as likely to have it themselves, and people with a parent and a grandparent with asthma were four times more likely to develop it. Because asthma is connected to allergies, a genetic disposition toward allergies, known as atopy, may explain some inherited asthma cases.

4. Asthma is surprisingly easy to diagnose.

One of the simplest ways to diagnose asthma is through a lung function test. If a patient is reporting asthma symptoms (coughing, chest tightness, a feeling of not getting enough air), their doctor may check the strength of their exhalations before and after having them use an inhaler. If their breathing improves with the medicine, they likely have asthma. An X-ray of the patient’s chest can also be used to reach an asthma diagnosis.

5. Kids who grow up around germs are less likely to have asthma.

A person’s environment early in life may also play a role in whether or not they develop asthma. People who grew up in rural areas, around animals, and in large families are less likely to have asthma than those who did not. One possible explanation is the hygiene hypothesis: According to this theory, kids who were exposed to germs and pathogens while their immune systems were developing are better equipped to deal with allergens, while kids who were sheltered from germs may be more likely to have an exaggerated (and in the case of asthma, potentially deadly) immune response to harmless substances. The hygiene hypothesis hasn’t been proven, however, and it’s definitely not an excuse to expose children to infections in an attempt to strengthen them against asthma attacks in the future.

6. Asthma triggers are everywhere.

To manage their symptoms, doctors tell asthma patients to limit exposure to their triggers when possible. Common asthma triggers include irritants and allergens like dust, tobacco smoke, car exhaust, mold, pet dander, and smoke from burning wood. Triggers that don’t come from the environment, like colds, sinus infections, acid reflux, and hyperventilation brought on by stress, can be even harder to avoid.

7. There's one asthma trigger patients shouldn't avoid.

Physical activity causes fast breathing, which can provoke asthma attacks in some people with the condition. There’s even a type of asthma called exercise-induced bronchoconstriction that specifically describes people who suffer from these kinds of attacks. But the risks of living a sedentary lifestyle outweigh those of exercising carefully, even with asthma. Instead of cutting out cardio altogether, doctors work with patients to come up with an exercise plan that’s safe for them. This might include warming up and using an inhaler before working out, practicing cool-down activities afterward, and wearing scarves or masks to limit exposure to irritants that may also trigger asthma symptoms.

8. There are two types of asthma treatments.

Long-term controllers and quick-relievers are the two types of medications used to treat asthma. Immediate medicines like short-acting beta agonists and anticholinergics relax muscles in the airways when flare-ups occur, and they’re typically administered directly to the lungs with an inhaler. Long-term medications help keep asthma symptoms under control over time are taken as often as once a day, regardless of whether symptoms are present. They include inhaled long-acting beta agonists and corticosteroids, biologic injections, and theophylline and leukotriene modifier pills and liquids. All of these medications suppress asthma symptoms by either relaxing muscles, reducing swelling, or preventing inflammation in the airways.

9. Asthma can be an occupational hazard.

Occupational asthma develops when a patient’s triggers come from their work environment. According to the National Institutes of Health, wood dust, grain dust, animal dander, fungi, and various chemicals are some of the most common asthma triggers that patients encounter in the workplace. Bakers, farmers, laboratory workers, millers, and woodworkers predisposed to asthma are all at higher risk.

10. There's no cure for asthma, but symptoms can lessen over time.

Though asthma is treatable, there’s no cure for the chronic illness. Some people, however, do appear to grow out of the condition after suffering from it as kids. It’s possible for asthma symptoms to become less severe and go into remission as patients get older, but once someone is diagnosed with asthma, the risk of an episode never goes away completely. Changes in hormone levels are a factor that could possibly bring asthma symptoms back in patients who haven’t experienced an attack in years.

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