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The Issues With Accuracy of At-Home DNA Tests
Companies like 23andMe and Ancestry are a more basic test but still offer exciting results. Shutterstock.

Testing Millions Of SNPs

For this, you will take a sample of the DNA and then check for a preset group of SNPs. Companies that do testing can test millions of SNPs at one time with these tests. Nevertheless, still, it is only a small amount of letters in your genome. 

Companies such as 23andMe and Ancestry rely on SNPs tests to determine their human DNA results. Some companies do the same for your dogs, such as emBark and homeDNA. If you’re looking into your cat’s DNA, you can use the Wisdom Panel or Optimal Selection. 

The Issues With Accuracy of At-Home DNA Tests
Doctors sometimes request DNA tests to see if you are at a higher risk of certain diseases. Shutterstock.

You Can See If You Are More Prone To A Disease

Most of these tests can be done without the recommendation from a doctor, but there will be occasions when doctors request that patients have their DNA tested to see if there have been changes in specific genes. 

It is useful to see if any alterations have been made to your DNA that makes you more prone to a risk of disease. The tests will be able to determine if the DNA by that gene has made changes for that specific person. 

The Issues With Accuracy of At-Home DNA Tests
Learning about where you come from can provide such exciting conversation topics in social settings. Shutterstock.

Learn About Your Ancestry

There was a time when DNA tests were mainly for health or paternity reasons. However, now it has become part of the current culture to know your history. Many companies are now branding themselves as “ancestry” services. They offer insight into who we are. 

These tests allow you to go way back in your family history and see where you originate. As exciting as this is, do these tests work when determining the test subject’s ancestry? 23andMe uses algorithms to get their results. 

The Issues With Accuracy of At-Home DNA Tests
Finding the meaning behind the string of DNA letters is what these companies do best. Shutterstock.

How The Algorithms Work

These algorithms use the string of letters as explained above and work with those to determine the results. While none of these letters are going to spell out exactly where you came from, thanks to the algorithm, they can find the meaning behind the letters. 

These companies do keep their algorithms secret. Their computers and systems are excellent at being able to discover a pattern. Researchers say that scientists have known about these techniques for a very long time. 

The Issues With Accuracy of At-Home DNA Tests
To compare your data, the company will need a lot of genetic samples to provide the results you want. Shutterstock.

They Need A Large Library Of Samples

How it works is that if a genetic anthropologist has a DNA sample, they can compare it to their library of other samples. Through this, they can understand which groups in their collection the sample is closely related. 

When getting down to the nitty-gritty, your paternal ancestry is tracked thanks to the Y chromosome. It is what fathers pass to male descendants. For maternal ancestry, this is found in mitochondrial DNA, which is what a mother passes onto all their children. 

The Issues With Accuracy of At-Home DNA Tests
Your DNA will be compared to entire lists of people from all around the world to determine your ancestry. Shutterstock.

Piece By Piece

Where the real details come from are the 22 non-sex chromosomes, which are compared against very extensive libraries of information. How does this work? The algorithm will take an entire genome and receive little pieces. 

For each piece that it takes, it will compare it to the reference data set. It will compare it to an entire list of probabilities, such as British and West African. This method is how you can understand the results of tests such as 23andMe. 

The Issues With Accuracy of At-Home DNA Tests
While these results are impressive, they are solely dependent on how big the company’s library is. Shutterstock.

Your Results In A Percentage

These tests come back with a percentage result. It might say something like, “You are 31% British.” This figure means that 31 percent of your DNA pieces compared the closest to the 23andMe library, which is considered to be British. 

However, the pitfall of this method is that the tests are only as good as the library of the company. They will need to have an incredibly extensive range of samples to compare yours to have an accurate result. 

The Issues With Accuracy of At-Home DNA Tests
The companies do not make their sample size public, so make sure to check up on reviews from previous customers. Shutterstock.

The Size Of Sample Groups

These libraries aren’t public, so you aren’t able to pick your company based on how big its genetic library is. 23andMe does, however, have much information on European populations as this is its biggest sample group. 

For information on Native American populations, they do not have as much as it is one of their least sampled groups. This notion means that their library will be able to tell you precisely what Jewish group you are from but will combine Native Americans into one general category. 

The Issues With Accuracy of At-Home DNA Tests
Be sure to follow the instructions included with the at-home DNA test very carefully. Shutterstock.

Making The Investment

So, now you have decided that you want to invest in finding out about your lineage through a DNA service such as 23andMe. It’s time to take a spit sample to send off to their laboratories for testing. How do you do this? 

Some people find it challenging to produce the amount of saliva that is needed for this test. When you have ordered your test, make sure that you read the instructions very carefully and also any information on how to provide the saliva sample.

The Issues With Accuracy of At-Home DNA Tests
It may be challenging to produce that amount of saliva, but you can rub your cheeks to help stimulate production. Shutterstock.

It’s Time To Make Some Saliva

If you are finding it challenging to produce the amount of saliva, there are some ways to help increase the amount of saliva you are providing. One of these methods is to take your hands and place them on the outside of your cheeks. 

You will then gently rub them, and this should stimulate saliva production inside your mouth. If that option doesn’t work for you, try to mimic a chewing motion with your mouth. Another incredible tip is to think about your favorite food. 

The Issues With Accuracy of At-Home DNA Tests
Try imagining sour foods such as lemons to get the saliva flowing freely in your mouth. Shutterstock.

Imagine Sour Foods Like Lemons

If this still hasn’t got you salivating, then you can imagine sour foods like lemons or sour sweets. You could also try smelling them if you happen to have them in your kitchen. This service says that they do not recommend that you bite or scrape your cheeks. 

The reason for this is that the cells in your saliva sample that will be analyzed by the company are your white blood cells and not the epithelial cells from your cheeks. These can get mixed in if you bite or scrape your cheeks. 

The Issues With Accuracy of At-Home DNA Tests
Make sure you collect your saliva sample in the 30-minute time frame for a good sample. Shutterstock.

How To Collect Your Sample

When you are collecting your saliva sample, you need to collect it all within a time frame of 30 minutes. You need to funnel the contents into the tube straight away. It prevents the DNA from degrading over the waiting period. 

If you wait longer than 30 minutes or delay releasing the buffer solution, your quality of the DNA could be compromised. Some people, however, have a condition in which their mouth is naturally dry or are on medication with this side effect.

The Issues With Accuracy of At-Home DNA Tests
Reverse the order by putting the buffer in first if you are struggling with the time limit. Shutterstock.

Releasing The Buffer

Instead of putting their saliva in first and then releasing the buffer, they will do it the other way around. The buffer will first be released into the tube and then topped up with saliva. 

If you are unlucky enough to spill the buffer liquid, you will need to request a new kit from the company. In total, you need to be able to produce a one-half teaspoon of saliva. It is estimated that it took an adult between 5-10 minutes to produce this amount.

The Issues With Accuracy of At-Home DNA Tests
Some people won’t be able to use DNA testing due to medical treatments and their effect on white blood cells. Shutterstock.

Who Can’t Use DNA Tests

Are there any groups of people who aren’t able to use this type of DNA testing? Yes, some individuals can’t. There may be certain people who are currently undergoing medical treatment. It could affect their white blood cell count. 

An example of this is chemotherapy. People who are undergoing chemotherapy have been advised that they should only do the test two weeks after their last treatment, or they can wait until their white blood cell count is normal. 

The Issues With Accuracy of At-Home DNA Tests
The DNA could be yours or your bone marrow donors, which makes results inconclusive. Shutterstock.

If You’ve Had A Bone Marrow Transplant

This restriction also applies to people who have received a bone marrow transplant. With this situation, it would be hard to discern whether the results were accurate on the DNA of the person wanting the test or from the donor. 

Consumers are going crazy for these tests, and they may seem very exciting and informative, but how accurate are they? They can tell you what diet works best for your body, your preference for certain foods, and medical conditions. 

The Issues With Accuracy of At-Home DNA Tests
A development in DNA testing in 2003 was the beginning of making it a commercial industry. Shutterstock.

DNA Testing Advanced In 2003

The critical development happened in 2003. It was when the Human Genome Project was able to deliver the human DNA sequence fully. Advanced testing showed that technology was able to read DNA results at an incredible speed and an affordable cost. 

This new tech has allowed it to become more popular and for people to use it for “fun” and not just for medical research. It increased the commercial interests from companies, and it became an excellent way for these labs to make money for the business. 

The Issues With Accuracy of At-Home DNA Tests
The main concern with DNA testing is if the sequencing is being done correctly to give the right results. Shutterstock.

Two Issues From DNA Results

As exciting as the potential is, two issues could come from the results and their accuracy levels. First off, people are concerned with whether the sequencing has been done well. Generally, it is accurate, but there are cases of failure. 

There was a company that wasn’t able to tell that the DNA sample was actually from a dog and not a human. Another analysis was done and found that 40% of variants that are related to specific diseases from genetic tests were false positives when the data was analyzed again. 

The Issues With Accuracy of At-Home DNA Tests
Due to the differences in company databases, there could be discrepancies when using multiple companies. Shutterstock.

It Doesn’t Sequence Your Entire Genome

But, when you assume that the tests have been done correctly, there are still some errors that can happen because of differences between individual companies and their DNA databases that they are comparing your DNA to. 

Most DTC genetic tests do not sequence your entire genome. Instead, they analyze positions in your DNA that are popular. There was one person who did DNA tests with a couple of different companies, and their results came out differently.

The Issues With Accuracy of At-Home DNA Tests
The results are all to do with what the company is using its codes for during testing. Shutterstock.

Different Results From Different Companies

One company said that they did not carry a gene that is associated with red hair. The other company they sent their spit off to, said that they did. What does this tell us? One of the companies was analyzing variants of the gene that code for red hair. 

What is the second concern? The Genome Wide Association Studies determine the positions of interest in DNA. When using a group of as many people as possible who have a shared trait such as red hair…

The Issues With Accuracy of At-Home DNA Tests
Genetics is more of a probability test rather than actual science, according to experts. Shutterstock.

It Only Offers A Probability

You then sequence their genes and look for specific places in their DNA that are the most similar to the group you are testing rather than a different population. With red hair, there are quite a few variants in the same gene that give someone ginger hair. 

When it gets more to more complex traits in a person such as taste or exercise, there will be many variants. For this, they only offer a probability of why you have that type of behavior when measured against the population. 

The Issues With Accuracy of At-Home DNA Tests
Just because you have two blue-eyed genes doesn’t mean you will have blue eyes. Shutterstock.

Will You Have Blue Eyes Because Of Genes?

This concept can be seen when looking at eye color as well. Someone may have a gene variant that is considered to be popular when someone has blue eyes, but it is just a probability. You might end up with brown eyes, even with two blue-eyed genes. 

Genetics is known as a probabilistic science. Some people are concerned with how these DNA tests offer to show their subjects their probability for specific medical conditions. You can discover more about the likelihood by researching punnet squares in regards to dominant and recessive genes. 

The Issues With Accuracy of At-Home DNA Tests
Even if your results say you are more likely to develop a particular disease, it doesn’t mean you definitely will get it. Shutterstock.

It’s Based On Your Lifestyle

It is still very likely that you will never develop this disease. This notion is influenced by your lifestyle as a whole and also just by chance. However, when it comes to checking at your ancestry, DNA is the best way to determine family relations. 

It can show precisely who your siblings and parents are as well as reuniting with long lost family members. While they offer to tell you where your family roots are from, they can’t do this. It can say where your most similar DNA is found on earth. 

The Issues With Accuracy of At-Home DNA Tests
DNA and heritage is a very complicated process that requires a lot of research and investigation. Shutterstock.

Fun And Trivial, Not Science

Ancestry tests are more fun and trivial than an exact science. It is fun to discuss what percentage you are of particular groups of people, but it won’t provide you much true scientific meaning. We have thousands of ancestors, and it is a very complex process to trace them. 

If you find yourself in the situation that requires a paternity test, this is also done through DNA testing and comparison. Many non-invasive prenatal paternity tests can be done that are highly accurate and also very safe. 

The Issues With Accuracy of At-Home DNA Tests
If you need a paternity test, do some research into options that are safe for the mother and baby. Shutterstock.

Paternal Testing

These tests can be done after the first nine weeks of pregnancy. What are the benefits of prenatal paternity testing? These tests analyze cell-free fetal DNA, which is found in the maternal blood, which means there is no chance of misdiagnosis or incorrect results. 

This technique means that testing is extremely accurate and reliable. Other tests use nucleated fetal cells, which may provide a less accurate reading. A blood sample is collected from the mother and not taken from the baby. 

The Issues With Accuracy of At-Home DNA Tests
The labs will need a blood sample from the mother and DNA swab from the suspected father. Shutterstock.

A Prenatal Paternity Test Without The Risks

Other tests are invasive and pose many other risks to the mother and the child to find out the paternity. Prenatal paternity tests, however, are unable to be performed when there has been In Vitro Fertilization or if it is multiple pregnancies. 

The labs using this testing will require the sample of maternal blood and then a mouth swab sample from the alleged father. The lab will then separate the blood plasma from the mother’s blood sample and locate the fetal DNA. 

The Issues With Accuracy of At-Home DNA Tests
You will have your much-anticipated results in just 5 to 7 days from when the test is done. Shutterstock.

How The DNA Is Tested

It will then be analyzed alongside the DNA samples from the mother and the suspected father. Using an algorithm, they will compare genetic markers between the fetal DNA and the father’s DNA. This test will then provide the answers you desire. 

A result should be ready within five to seven working days, but some places offer an express testing option. It should get the results to you in three to four days. For express testing, most situations require the mother to be at least ten weeks pregnant.

The Issues With Accuracy of At-Home DNA Tests
DNA testing is a fun way to learn more about yourself and your history. Shutterstock.

Learn More About Yourself

DNA is a fascinating thing to learn more about and try to understand its complexities. It can provide us with interesting facts about ourselves that we would have never known if we hadn’t sent off some spit in a tube. 

However, these results need to be taken with a pinch of salt as some of the results are based on probability rather than actuality. There are cases when DNA testing is entirely accurate and useful, such as in family and paternal testing. 

Sources:

https://www.theguardian.com/science/2017/jul/23/what-i-learned-from-home-dna-test-kits-are-they-accurate-or-worthwhile#maincontent

https://www.sciencenewsforstudents.org/article/explainer-how-dna-testing-works

https://www.livescience.com/62690-how-dna-ancestry-23andme-tests-work.html

https://customercare.23andme.com/hc/en-us/articles/202904540-Tips-for-Providing-Your-DNA-Sample

https://customercare.23andme.com/hc/en-us/articles/202904520-Who-can-use-the-23andMe-kit-

https://www.scientificamerican.com/article/how-accurate-are-online-dna-tests/

https://www.easydna.ie/prenatal-paternity-test/

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