What to know about your options for genetic testing

July 10, 2022 3:30 PM

Robert H. Shmerling, M.D., Harvard Health Publications

Posted: July 10, 2022 3:30 PM

Updated: July 12, 2022 2:14 PM

When it comes to health and disease — and, of course, many other aspects of life — one thing is certain: genes matter. A single gene mutation can cause some conditions, such as sickle cell anemia and cystic fibrosis. More often, multiple genes are involved in disease development, and they act in concert with nongenetic factors, such as diet or exercise, to affect disease risk.

Several companies offer you the opportunity to look at your genes. But how might that help you from a health standpoint? And how do such tests differ from the genetic testing a doctor may recommend?

Genetic testing is on the rise

Genetic testing was nearly unheard of only a few decades ago. Now, you or someone you know has likely had genetic testing within the last year or two.

And while health care providers can now order far more genetic tests for their patients than in the past, you don’t need a doctor’s order to request this. Companies like Ancestry.com and 23andMe are ready and willing to check your genes for variants associated with certain health conditions, as well as your family ancestry.

In fact, spending on direct-to-consumer genetic testing is predicted to reach $2.5 billion within the next few years.

Is all of this testing useful?

For some people, the answer is clearly yes. When performed accurately, genetic tests can uncover a disease or a tendency to develop certain conditions, and it can lead to close relatives getting tested as well. Preventive measures or treatment can be lifesaving.

In the following four examples, knowing you might develop a condition or are a carrier can help direct medical care, and may inform life decisions or encourage you or other family members to consider genetic counseling.

Hemochromatosis: This is a genetic condition in which too much iron is absorbed from the diet. The extra iron can harm important organs like the heart and liver. Once a person is diagnosed, phlebotomy (blood removal, similar to what happens during blood donation) and avoiding iron supplements can prevent serious complications such as diabetes and liver failure.
Prenatal testing: For people planning pregnancy or who are already pregnant, genetic testing is available to check for an extensive number of conditions, such as cystic fibrosis and Down syndrome.
Cancer: A number of genes are known to increase the risk of certain cancers. Testing may be especially important for people with a family history of these cancers. Perhaps the most well-known are BRCA mutations, which increase the risk of breast, ovarian, and several other types of cancer.
People who don’t know their family’s medical history: For example, a person who is adopted and has no information about family medical problems may learn they are at increased risk of a preventable disease, such as heart disease or colon cancer.

But the answer can also be no. Results of genetic testing may provide information you already know, may be misleading or may even be distressing.

For example, learning you’re at increased risk for developing Alzheimer’s disease late in life may be more upsetting than useful, as there are currently no reliably effective preventive treatments.

What about the costs of genetic testing?

Genetic testing may have more than one kind of cost. A doctor-ordered genetic test may be covered by your health insurance, but it’s unlikely that an over-the-counter test will be. And, as one company states on its website, “knowing about genetic risks could affect your ability to get some kinds of insurance.”

Not all genetic testing is comprehensive

A 2021 study on testing for a genetic cholesterol disorder, published in the medical journal JAMA Cardiology, demonstrates how direct-to-consumer testing may be misleading.

The researchers looked at genetic testing for familial hypercholesteremia (FH), a condition caused by complex gene variants that greatly increases the risk of heart attack, stroke and other health problems. Researchers compared the results from a doctor-ordered comprehensive panel test (which included more than 2,000 gene variants) with results from direct-to-consumer genetic testing (24 variants) provided by 23andMe.

Among more than 4,500 people tested for a medical reason, such as evaluating an unexpectedly high cholesterol level, the more limited testing would have missed important genetic variants for:

nearly 70% of study participants
nearly 94% of Black and 85% of Hispanic individuals
about a third of Ashkenazi Jewish individuals

This suggests that a large number of people would be falsely reassured by the results of their genetic tests for FH if they relied on the type of screening offered by a popular over-the-counter product.

And results may be particularly unreliable among persons of color.

The bottom line

You can’t pick your genes, but thanks to an ever-expanding menu of options, you can pick your tests.

In many cases, it’s best to review your decision to have genetic testing with your doctor before having it done.

You may choose to see a genetic counselor about the ramifications of testing before you jump in and let your doctor do the testing, rather than ordering it yourself.

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Although the longstanding debate between nature versus nurture is often framed as one being dominant over the other, scientists today know it’s not that simple: Nature and nurture interact in complex ways.

You probably already know that your parents and family history play a big role in determining your physical features, from the color of your hair to your height. But did you know that genetics also has an influence on some of your personality traits too? To create a list of traits that have some of their origins in genetics, Top10.com collected information from scientific journals such as Nature Genetics and the Proceedings of the National Academy of Sciences.

Today, more is often known about the genetic component of inheritable medical conditions such as hemophilia, a blood clotting disorder, and Huntington’s disease, a degenerative condition affecting the brain’s nerve cells. But according to a study published in Nature Genetics, more is being discovered about how traits like extraversion, creativity, and compassion, may also have correlations to specific genetic variants.

We’ve only scratched the surface of what genetics can tell us about who we are, but researchers are hopeful that with more study, we’ll unlock more about how psychological traits are impacted by genetics and environmental factors. Here are 10 physical and psychological traits that researchers have determined have some of their origins linked to genetics.
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A 2006 study conducted in Israel found facial expressions associated with concentration, sadness, and anger can be inherited. Researchers videotaped 21 people born blind and 30 of their relatives born sighted. Participants were asked to solve challenging puzzles, listen to a disgusting story, recount a sad or joyful personal experience, and respond to a silly question. Those who were blind had very similar facial expressions to their sighted relatives when concentrating or feeling angry or sad. Moreover, a computer program able to recognize similar facial expressions correctly matched blind participants with their relatives 80% of the time.
sruilk // Shutterstock
The septum is the bone and cartilage in the nasal cavity that divides it into two nostrils. The septum can become deviated, or crooked, making it difficult to breathe. A deviated septum is most commonly the result of trauma, such as a blow to the face. However, it is also associated with conditions that affect connective tissue, such as Marfan syndrome and Ehlers-Danlos syndrome, both of which are genetic.
LightField Studios // Shutterstock
A team led by researchers at the University of Basel in Switzerland found maternal symptoms of insomnia were associated with a child’s sleep pattern as objectively measured by in-home electroencephalography. Maternal insomnia was associated with less total sleep time, more stage 2 sleep, less slow-wave sleep, a later time to sleep onset, and a later wake time for their child. The insomnia symptoms of both parents influenced their perceptions of their children’s refusal to adhere to a designated bedtime, duration of sleep, sleep anxiety, incidents of waking up during the night, and/or daytime sleepiness.
Dave Hogan // Getty Images
A V-shaped frontal hairline, often called a widow’s peak, is a morphogenetic trait inherited by people from their parents. It has also been associated with a number of inherited genetic conditions. Reports also exist of a link between a widow’s peak and craniofacial clefts, or malformations of part of the face. However, the association between a widow’s peak and the severity of these conditions has not yet been defined.
santypan // Shutterstock
Every person responds differently to caffeine. Scientific evidence that these responses may be genetic is increasing. Genetic factors may directly influence individual responses by changing acute or chronic reactions to caffeine. These factors may also play an indirect role by altering the psychological or physiological processes related to the effects of caffeine, such as sensitivity to anxiety and the generally reinforcing effects of substance use. Genes can also affect the body’s response to long-term caffeine use.
Vadym Ivanov // Shutterstock
About one-fourth of the population has a taste receptor gene, TAS2R38, that can make foods such as leafy greens and hoppy beers taste bitter. The perceived bitterness of these foods varies among individuals and depends on how strongly compounds in foods bind to the receptor. In a 2014 study of 93 Caucasian participants, TAS2R38 was associated with a bitter taste on the papillae of the tongue when it was swabbed with ethyl alcohol. The researchers concluded that genetic variations in the TAS2Rs gene may explain why alcoholic beverages taste bitter to some people but not to others.
MIA Studio // Shutterstock
Autosomal Dominant Compelling Helioopthalmic Outburst syndrome, appropriately known as ACHOO syndrome, is characterized by sneezing after sudden exposure to bright light, usually strong sunlight. The cause of ACHOO syndrome is not well understood. However, researchers do know it is inherited as an autosomal dominant trait, so if one parent is affected, a child has half a chance of inheriting ACHOO syndrome.
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The oxytocin receptor gene, also known as the OXTR gene, codes for the oxytocin receptor, to which the hormone oxytocin binds and exerts its effects throughout the body. Studies have linked part of the OXTR gene to psychological resources including optimism. The findings of a 2011 study suggest those who inherited a certain variation of the OXTR gene from both parents are more optimistic than those who inherited the variation from one parent or not at all.
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In 2014, researchers presented a paper at the American Academy of Neurology’s annual meeting identifying four genes associated with pain perception: DRD1, DRD2, COMT, and OPRK1. The researchers enrolled almost 2,800 people who took opioids for chronic pain in their study. The DRD1 gene was 33% more prevalent among those with low pain perception than those with high pain perception. The COMT gene was 25% more common among those with moderate pain perception compared to those with high pain perception, and the OPRK1 gene was 19% more common. Among those with high pain perception, the DRD2 gene was 25% more prevalent compared to those with moderate pain perception.

Identifying these genes can help physicians better understand why some of their patients perceive pain differently than others, according to author Tobore Onojighofia, a member of the American Academy of Neurology and scientist with Proove Biosciences.
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A study of twins published in 2012 by an international team of researchers found genetics explain about 33% of the variation in reported life satisfaction. Although at first the researchers found people with a certain variant of the 5-HTT serotonin transporter gene reported greater life satisfaction, they had difficulty replicating their results in an independent sample. The researchers said their findings suggest more work is necessary to better understand the relationship between the 5-HTT gene variant and life satisfaction.

This story originally appeared on Top10.com and was produced and distributed in partnership with Stacker Studio.
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In recent years, there's been a dramatic increase in genetic testing.