The human genome consists of 23 pairs of chromosomes: 22 of them are non-sex chromosomes and the last pair are the sex chromosomes. The 22 pairs of chromosomes are the autosomes and the DNA that is encoded in them is called the autosomal DNA.
What Is Autosomal DNA Testing And Why Should I Test?
The human genome consists of 23 pairs of chromosomes: 22 of them are non-sex chromosomes and the last pair are the sex chromosomes. The 22 pairs of chromosomes are the autosomes and the DNA that is encoded in them is called the autosomal DNA. So when you take an autosomal DNA test from any of the genetic genealogy companies like AncestryDNA, Family Tree DNA, 23andMe, or MyHeritage DNA, you are getting tested for these 22 pairs of autosomal DNA in addition to X, Y and Mt DNA. The autosomal DNA is inherited from either parent and therefore their occurrences in pairs- one from the mother and the other from the father. They in-turn would have received their genes from your grandparents.
Are there are other types of DNA tests? Which is the best?
Autosomal DNA Versus Mt DNA
As mentioned, there are the sex chromosomes X and Y (X inherited from mother and Y from the father). Generally, if you are a male you would have XY combination and if you are a female, you would have XX. Additionally, there is the Mitochondrial DNA which comes from the organelle, Mitochondria (also known as the powerhouse of the cell). Mitochondrial DNA is small (16,569 base pairs) and is inherited from your mother. Just to give you context, the smallest autosomal chromosome is chromosome 21 and its size is 48 million base pairs. So when you are getting a mitochondrial DNA test (MtDNA test), you are getting your entire mitochondrial genome sequenced.
Autosomal DNA Versus Y-DNA
Autosomal DNA and Y-DNA are two distinct types of DNA that can be used to trace ancestry and make family connections. Autosomal DNA is inherited from both parents and is passed down from generation to generation in both males and females. It contains information from all of an individual's ancestral lines, and is the most common type of DNA analysis done for genealogy purposes. Y-DNA, on the other hand, is passed down solely through the male line and is only found in males. Y-DNA analyses trace a person's direct paternal line, which can help uncover the heritage of a particular surname and reveal relationships between people of the same surname. Y-DNA tests can also be used to connect individuals with distant relatives, confirm family relationships, and determine ethnic origins from many decades in the past.
What is microarray-based autosomal DNA testing?
Companies like AncestryDNA, 23andMe, FTDNA, MyHeritage and Living DNA perform SNP genotyping (also known as Microarray technique). In this methodology, single DNA bases are read and used to determine who your close relatives (siblings, parents) and distant relatives (second cousins, third cousins, great grandparents etc) are.
How accurate is autosomal DNA testing?
Whole Genome Sequencing (WGS) is another methodology with which testing companies can sequence every single base pair in your DNA. While this technique is more accurate compared to SNP genotyping, it is also the most expensive. If a book was an analog of your genome, WGS will read the entire book and SNP genotyping will read specific words on certain pages of the book. As you can imagine, WGS is >10x more expensive compared to SNP genotyping.
If higher accuracy is your objective, especially when it comes to health traits, opt for WGS as your DNA test results can give you several more insights that a normal microarray based ancestry test would not. In general, autosomal DNA tests can identify close relationships between individuals, such as parent/child, sibling, or grandparent/grandchild, with a 99.9% accuracy rate. The accuracy rate for identifying more distant relationships, such as first and second cousins, can be between 80-90%.
Using Autosomal DNA in Genetic Genealogy
Autosomal DNA testing is used in genetic genealogy to trace ancestry. Autosomal DNA testing looks at a person's entire genome, which contains genetic markers inherited from both parents. By comparing a person's DNA to that of other individuals and to reference populations, genetic genealogists use autosomal DNA testing to trace a person's ancestry and build a family tree. Autosomal DNA testing can also be used to identify relatives, both distant and close, who share DNA segments with each other.
How many SNPs are present in your DNA data?
When you open the DNA raw data file from your ancestry testing companies you can see several thousand lines >600,000. Each of these lines represents a base pair in your genome.
|Name||No. of SNPs||Genotyping backbone|
|Ancestry DNA||637,639||Customized Illumina's GSA|
|23andMe||630,132||Customized Illumina's GSA|
|MyHeritage||702,442||Customized Illumina's GSA|
|FTDNA||612,272||Customized Illumina's GSA|
|Living DNA||759,757||Customized Illumina's GSA|
Few things you should know about autosomal DNA transfer
DNA testing companies also provide access to your DNA data. This data belongs to you. You can download this data and keep it on your cloud or local device for reference and future use. You can also upload or transfer your DNA data to other companies to find other DNA matches. But before you go ahead and upload your data, here are few things you might want to consider.
What measures are being taken for data privacy and security?
This is one of the most important things you should consider before performing an autosomal transfer to another third-party website/database. You have to ensure that the website follows certain basic practices in safe-guarding your data. Even websites like Gedmatch and MyHeritage have been victims of security breach in the past.
What DNA data formats does the third-party website accept?
Another big challenge that many genealogy enthusiasts face is the format of DNA data that each company provides. Companies like 23andMe and LivingDNA follow a 4 column format (SNP, Chromosome, Position, Genotype) nomenclature while others like AncestryDNA follow a 5 column format (SNP, Chromosome,Position, Allele 1, Allele 2). Before you upload your DNA data make sure that your format is acceptable. If not, you may have to use some other tools to convert to a specific format before you upload.
The Benefits Of Autosomal DNA Testing
There are several reasons why you might want to learn more about your ancestry. First, knowing where you came from can help you understand who you are today. It's also helpful when trying to figure out your family history. Knowing your heritage can give you insight into your genetic predispositions, such as whether you're at higher risk for certain diseases. Finally, learning about your ancestry can help you connect with others who share similar backgrounds.
How Long Does It Take For Results?
If you order an autosomal DNA kit now, you will receive your saliva collection kit within 1-2 weeks depending on the shipping format. Some companies offer expedited shipping options so you can get your results even faster. Once you collect your samples and send it back to your DNA testing company, it will take anywhere between 3-4 weeks for your results to arrive.
Sample DNA raw data of Autosomal DNA testing companies
There are several reasons why you should consider ordering an autosomal DNA kit today. First, there are many benefits to knowing your genetic history such as understanding your family tree better. Second, you can learn about yourself by comparing your results with those of other people who have taken the same test. Finally, you can also use the autosomal DNA data to learn more about your health and how to improve it.