The ABC’s of At-Home DNA Test Kits
(Written by Sara Arthurs, staff writer for The Courier. Story originally published on June 21, 2018).
Personal genomics testing can give you a glimpse into your DNA – information that is, in essence, “the instructions that make you, you,” said Abby Levitt, Ph.D.
Levitt, assistant professor of biology at the University of Findlay, gave a recent presentation on the topic of the increasingly popular at-home DNA tests at the Findlay-Hancock County Public Library.
“You are made of lots and lots and lots of little cells,” she said.
The nucleus of the cell houses DNA. If you could stretch out the DNA within the nucleus of a single cell, it would measure 2 meters. And if you stretched out all the DNA in your body – the 10 trillion cells in each person – “you could make it to the sun and back four times,” Levitt said.
Since there is so much information, DNA tests look for specific things.
DNA is made of nucleotides, which come in four “flavors”: A, C, G and T. A DNA test involves looking up SNP (pronounced “snip”), or single nucleotide polymorphism.
Say everyone has a C at a specific point, and something happens to change it to a G. A SNP is this specific point where the swap occurs. This little swap might result in changes to a physical feature, like eye color or height. Genetics will influence how your body reacts to certain drugs – for example, whether ibuprofen or acetaminophen works better for you. It might be that people from Italy always have a T at a certain spot, and people with West African ancestry always have a C.
Along your genome are millions of SNPs. Different testing companies look for different ones.
Chromosomes, wellness and Neanderthals
Chromosomes are “discrete units of DNA.” Humans have 23 pairs – one in each is from your mother and one from your father. The final chromosome is the sex chromosome, XX or XY.
But you don’t get one whole chromosome from each of your parents, Levitt said. When a sperm fertilizes an egg, the chromosomes recombine. The information is swapped around, so you get little pieces from each of your parents. The results are different in everyone, so siblings inherit different information. This is why one sibling might be 30 percent Italian, and another 47 percent Italian.
Levitt focused her talk on the company 23andMe, which recently added an option to offer information related to health and wellness, as well as ethnic background. These tests use saliva or a cheek swab. Levitt said people associate DNA with blood – “from the crime shows” – but every one of your cells contains DNA.
Saliva is a secretion that your body makes, not part of your body, so it isn’t made of your cells. However, your cheek and tongue cells slough out into your saliva, and that’s what the test looks for. This is why you’re not supposed to eat or drink before taking the test, as it will wash out the cells.
Both men and women can look at the maternal line. But women who want to learn about the paternal side must get a male relative to participate.
The tests can tell you your ethnic background, but the majority of the better-known companies are geared toward people with European ancestry, said Ruth Wilhelm, of the local history department of the Putnam County District Library. She presented on the topic at the library’s Ottawa location.
Wilhelm herself learned, “I’m a Neanderthal. My brother got a chuckle.”
Levitt said Neanderthals are a different species that lived alongside humans for some time, breeding with them. If you are of European descent, you may have some Neanderthal DNA, Levitt said.
She said 23andMe also offers a “trait report.” People who “really don’t like dark greens” may have more of the genes that allow them to taste bitterness, and the report can point this out.
Another report Levitt advises taking “with a huge grain of salt” deals with wellness – such as what your genetics say about your ability to sleep deeply, or your weight. She said environment may be more important in determining some of these results. If you have young children at home, you probably don’t sleep deeply, even if you’re genetically predisposed to, and “if you really enjoy cheesecake” you might weigh more than your genetics would indicate.
And the test may show a likelihood to develop a disease, or whether you are a carrier and might pass a disease on to your children.
The information that is your DNA is “like a cookbook,” Levitt said. The recipes are there, but not necessarily the finished dish. The DNA is information, but you don’t use it until you “express” those genes. And not all genes are expressed in all cells. Your skin and liver cells have the exact same genome, but you aren’t using all the pieces in each.
So learning you have a health-related gene mutation, such as one associated with Alzheimer’s disease, just means that the information is present in your cells, not that you will necessarily get sick. A lot of factors can turn it “on” or “off” including exercise, diet and exposure to toxins.
It’s different with something like cystic fibrosis, which is a recessive disorder. This involves a more straightforward cause and effect: if your child has two copies of the gene mutation, he or she will have cystic fibrosis.
Many different gene mutations can lead to a greater likelihood of breast cancer, and the testing company is searching for only specific versions of the mutation – sometimes the rarer ones. So if the report says you don’t have BRCA1 (a gene mutation associated with developing breast cancer), it actually just means you don’t have the variant they were looking for.
Levitt said she’s concerned people might discover, say, a likelihood to develop late-onset Alzheimer’s disease and “start panicking.” You may genuinely want to know, but think it through first and remember that many other things play a role.
Levitt said breast cancer risk, in particular, is linked to physical activity. Just as certain things might turn a gene “on,” “Exercise can actually turn stuff back off.”
She said medical genetic testing at a doctor’s office is different, and more specific.
Good news, bad news
Through personal genomics, you might find relatives you didn’t know you had, or they might find you. This could be a great thing, Levitt said. But it can also reveal skeletons in the closet. Maybe you learn you were adopted, and your parents never told you. Maybe your father isn’t actually related to you.
Wilhelm gave some examples she had read of surprises good and bad. One case involved a woman who found out her father wasn’t her biological father. It turned out that her parents’ fertility doctor had used his own sperm while her parents were trying to conceive a child.
She also read of a man who found out he fathered a child he never knew about while serving in the Marines overseas, and a woman who learned “her father was a baby that was switched at birth.” In the latter case, the two families eventually became friends and “went on a cruise together. So now they have a great big family,” Wilhelm said.
Levitt said it’s also possible that other people will find out things you don’t want them to know – say, an employers, or an insurance company.
Current law prohibits health insurance companies from charging higher premiums based on genetic information but insurance companies are likely to challenge this, and to argue that if you might be more likely to get cancer, they should charge you more, Levitt said.
And while health insurance companies cannot discriminate, Wilhelm said life insurance, disability insurance and long-term care insurance companies can ask if you have taken the gest and can request raw data.
If you look at the fine print, Wilhelm said, the DNA testing company may automatically do the health test, whether you pay for it or not. She said there have already been cases of people denied life insurance because of the tests. She recently read of a 36-year-old single woman in good health who had adopted a baby. The new mother was denied insurance because the raw data showed that she had a gene that might lead to cancer.
Law enforcement can also use the information. Levitt mentioned two examples of murders solved this spring through personal genomics. The police had a blood sample from the “Golden State Killer,” but his DNA didn’t match anything in their databases. So, Levitt said, police went online to see all publicly available family trees and eventually located a distant relative. Several weeks later, another killer was arrested for a 1987 double homicide in Washington state.
One audience member said that, since making your information private wouldn’t help you or anyone else doing genealogical research, “That outweighs the dangers.”
If you’re not worried about protecting a criminal, it’s probably OK, Levitt replied. But in general, “Do your homework.” If you haven’t picked a particular company, look into different ones and “read all the fine print,” she said.
Wilhelm said there are more than 200 companies worldwide that offer these tests, with the cost ranging from $29 to $2,500.
If your biggest question is where you came from, Levitt recommended AncestryDNA, which has the largest database and looks at the most pieces, so you will get the most information.
Wilhelm said results may vary. She herself got different results from three companies. Only one picked up her Finnish heritage, and only one picked up her ancestry from the Iberian peninsula.
Also consider whether the company will sell or share your information, and, if so, how much this matters to you.
One testing company, for example, states in the fine print that they will sell your data, scrubbing it of any information that would identify you. This information is valuable to researchers and pharmaceutical companies, Wilhelm said. She said there is “good stuff” coming out of this. It’s expensive to develop new medications, and having access to this data may make it easier to develop new drugs that could help people, she said.
But many people might be uncomfortable with their data being sold. If later, you decide you don’t want to be part of biomedical research, “Your DNA’s out there… They will have it forever,” Wilhelm said.
Wilhelm said she gave the presentation after hearing from a lot of library patrons who had asked about the tests while researching their genealogy.
And Carolyn Dahms, reference associate at the Findlay-Hancock County Public Library, who organized Levitt’s presentation, said these tests are popular right now.
Dahms has been tested herself. She said once you learn about your ancestors and their struggles in life, to get to where you are now,” It makes you appreciate your life more.”