Home Insights Genomics All you need to know about genealogical DNA tests?

All you need to know about genealogical DNA tests?

Genealogy DNA tests are fun, informative, and reasonably priced. With more than 700,000 analyzed markers, they open new ways to unravel the past and potentially meet with distant cousins.

genetic genealogy
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Genealogical DNA tests are now hugely popular. As of August 2019, it is estimated that more than 30 million people had their DNA tested for genealogy purposes. Thus, things have evolved dramatically in the last ten years.

Seven years ago, I attended a Genealogy Conference in London, and believed it or not. We were less than a handful of companies offering such services, with AncestryDNA, known as Ancestry.com being already the leader.

The whole concept of genealogy started to get traction in the early 2000s with the publication of “The seven daughters of Eve” by Oxford geneticist Bryan Sykes. He introduced the mitochondrial Eve’s concept by tracing back mutations in the mitochondrial DNA transmitted directly from mothers to daughters. Sykes classified all modern European into seven genetic groups, called Haplogroups. All of these groups sharing a common genetic ancestor, the mitochondrial Eve.

Analyzing your DNA is the key to unlock the past!

But what is Genetic Genealogy, and why is it useful? In each of your cells, you carry the history of the world. By analyzing your DNA data, you can not only discover some genetic diseases, but you also have the ability to travel back in history. This is because your family history lies in just 2 strands of sugary molecules.

Genealogical DNA tests offer a way to discover relationships between individuals by analyzing mutations. It allows us to identify some distant cousins and to know more about your family’s history.

Analyzing your DNA unveils the migrations of your ancestors and ultimately learn more about yourself. This is not only instructive but also fun as the major DNA testing companies rely on their massive database to potentially connect you with distant family members.

How to collect a DNA sample?

For most of the tests, the procedure for DNA collection is straightforward. The two main testing companies on the market, AncestryDNA, and 23andMe use saliva samples. The collection of approximately 2ml of saliva, half a teaspoon. This doesn’t seem a lot, but it can be difficult for some people to produce such an amount.

Some tricks to produce more saliva involve gently rubbing your cheeks from the outside (pressing them against your teeth and gums) before spitting into the tube. Another way to encourage saliva production is by placing 1/4 teaspoon of white table sugar on your tongue.

Once the collection tube is filled with the recommended amount of saliva, the next step is to add a DNA stabilizing agent.

The other DNA Collection method is to use a swab test. It consists of a long sterile Q-tip. Then, by gently scraping your inner cheek, the cotton will collect cells from which the DNA will be extracted. The companies’ Family-Tree DNA and MyHeritage DNA favor this method.

All of the DNA testing services provide a pre-aid envelop or box to return the sample for processing. It really could not be easier! To ensure a proper collection, remember not to drink, eat, smoke, or chew gum 30 minutes before collecting the DNA.

Are DNA tests different from sequencing?

Yes, they are! Before getting into the different DNA types analyzed to unravel family connections, let’s stress the differences between full genome sequencing and a DNA genetic genealogy test.

The best analogy is to look at a book, full of pages, full of words, and full of letters. But, when we say full of letters, it is not true actually. The alphabet of life is only based on 4 letters representing the four chemical compounds used to build any living creature on earth.

If we represent our DNA as this book, full genome sequencing will read all of the letters, one after another. Then, DNA test companies will just read through the book to detect words of interest.

The process of checking for specific words or variants is called Genotyping. To detect the words or DNA sequences of interest, the companies will need to know what they are looking for.

What are the different types of Ancestry DNA tests?

Genealogical DNA comes in three different flavors: Autosomal, Y-Chromosome, and Mitochondrial. When transmitted to the children, the DNA may not be intact and may carry a mutation. These mutations are called Single Nucleotides Polymorphisms (SNPs) and are the genetic markers used to trace back the history and migration of your family.

What is the autosomal DNA?

All of our genetic material lies in 23 pairs of chromosomes being made of compressed DNA. Half of our genetic material comes from the mother and the other half from the father. It sounds like Embryology 10; sorry for that! Just stay tuned; the best is yet to come. Out of these 23 pairs of chromosomes, 22 are not involved in defining the sex of an individual. Instead, they carry what is called autosomal DNA. Most of the DNA testing companies analyze the mutations carried by this type of DNA.

As half the autosomal comes from the father and the other half from the mother, one of the drawbacks of autosomal DNA is that mutations can be “diluted” over time.

autosomal DNA

What is the mitochondrial DNA?

Mitochondrial DNA (or mtDNA) is the DNA we inherit from our Mothers. Both males and females can use MtDNA testing to explore an individual’s direct maternal line. It travels through the maternal lineage and allows us to go back to the mythic mitochondrial Eve.

Despite her name, the Mitochondrial Eve was not the only living female of her time. She lived between 237,000 and 581,000 years. She somehow is the only one of her contemporaries to have produced a direct, unbroken female lineage.

Despite Eve being our most common maternal ancestor, we do not share her exact DNA. The mutations in the mtDNA are said to occur every thousand generations, and as a result, mutations are rare within a family line. This is especially useful for carrying deep ancestry analyses.

mtDNA

What is the Y-Chromosome DNA?

When it comes to transmission, the Y-DNA is the opposite of the mtDNA. Y-DNA is the DNA carried down the direct paternal line. It is inherited from a man’s father, who got his from his father, all the way back to the end of the line.

Unlike autosomal DNA, the Y-DNA does not undergo recombination. Instead, it stays intact and provides geneticists with an incredible opportunity to trace a genetic lineage far back in time, all the way back to our most common paternal ancestor known as the Y-Chromosomal Adam.

As males only transmit the Y-DNA, only boys can use it to know more about their paternal lineage.

Y-DNA

How is the DNA sample analyzed?

As we said, the DNA testing results rely on the analysis of the SNPs that are transmitted from generation to generation. The higher the number of markers, the most precise the results will be.

Most of the companies use the same procedure. The DNA is first extracted from the saliva or the swab. The technology used is known as a DNA chip. A DNA chip is a tiny thumbnail-sized tool that contains thousands of nucleotide patterns attached to the chip in a grid pattern. For example, AncestryDNA uses a chip containing approximately 700,000 markers.

The attached markers will act as probes and tell a researcher whether a DNA sample contains particular DNA sequences and mutations. The results from the DNA chip are then analyzed using a powerful computer.

What can you really learn with a genealogical DNA test?

The genetic genealogy companies will use the genetic data to offer ethnicity estimates. OK….but what does it mean? The world is divided into regions, and each region will contain specific mutations. This is mostly because hundreds of years ago, the population did not travel a lot and mostly stayed in the same areas for numerous generations.

DNA ethnicity
Source: www.genealogyexplained.com

Mutations became a specific marker of an area. By analyzing your DNA mutations, it is then possible to better understand the path followed by your ancestors.

The major companies offering genealogical DNA tests maintain huge databases containing millions of DNA data samples. They also offer potential DNA matches with family members that you may not be aware of. An exemption can be for people having received a bone marrow transplant. The results may be linked to the DNA of the donor.

Are DNA Ancestry tests really worth it?

For genealogists, DNA Ancestry tests have a clear, informative value. But you do not need to be focused on building your family tree to use this test. Prices have dropped so much in the last couple of years that it is just a fun way to explore your past.

Health DNA tests are different, and we will explore the concerns we have about them in another article, but as far as genealogy is concerned, we encourage you to give it a try. Maybe you will extend your family with newly found members.

Companies to consider

With so many providers on the market claiming to give you access to your deep ancestry make-up, choosing one can be a daunting task. Our recommendation is to stick to the basics and to rely on the main players. The accuracy of the results is highly dependent on the size of the underlying Database.

Hence, considering that the companies use more or less the same technology to analyze the DNA, what matters is the database, privacy of the results, and experience.

By picking one of the top 3 players presented below, you will benefit from the expertise in this field. As for the price, they all offer very close price points. The difference is to benefit from one of the numerous discounts or campaigns they conduct several times per year.

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