DNA Testing Fundamentals: What is DNA Testing and How Does It Work?

DNA testing is an excellent tool for learning about your family’s history, and it is now more accessible than ever before. You can receive a percentage breakdown of your ethnic origins and identify previously undiscovered relatives based on common DNA with a simple cheek swab — no spit or blood required. You can also confirm any known familial links. But what happens in the four weeks between swabbing the inside of your cheek and receiving your results? What does one tiny cotton swab have to do with all of this exciting and essential data?


Analytical biology

Epithelial cells adhere to the cotton swab while swabbing the inside of your cheek. Epithelial cells are readily available and may be obtained without causing harm. The cells retrieved by the cheek swab are germline cells, which means their DNA is passed down from your parents (as opposed to somatic cells which include mutations that you acquire over your lifetime).


A nucleus is found inside each of these cells, and each nucleus contains a copy of your DNA, or genetic material. Because DNA is a relatively stable molecule that isn’t readily damaged by changes in temperature or being thrown around in the vial, sending it to the lab by standard mail without any particular measures like dry ice or special packing isn’t an issue.


We prepare your DNA for our genotyping test as it arrives in the lab, which determines if you have an A, T, G, or C at particular variable sites in your DNA sequence. This is a highly precise approach for assessing how similar or dissimilar your DNA is from that of everyone else in our rapidly expanding DNA database.


To begin, the DNA is separated from everything else in the vial, including the liquid, cotton swab, and other elements of the cell that aren’t DNA. We can only extract a little bit of DNA from the sample you give, and it’s too tiny to deal with. This is why we must first amplify the material by duplicating your DNA sequence numerous times. We concentrate on the 700,000 parts that are known to differ across individuals (the other 99.9 percent of the sequence is pretty much the same for everyone). SNPs are the abbreviation for these regions.


These enhanced pieces, or fragments, are then placed onto a tiny chip with a large number of pores. Each pore contains a bead that attaches to certain DNA snippets. The amplified fragments that were poured over the beads naturally bond to their particular beads, allowing the following phase in the procedure to be informative. The following step assigns a red or green fluorescent signal to each piece.


DNA fragments are linked to beads in the chip’s pores and labeled with fluorescent signals in this schematic illustration of a genotyping chip. 


The chip is then read by specialized software, which converts the colors into A’s, T’s, G’s, and C’s. The file containing that sequence serves as the starting point for the following process, which is computational analysis.



Analytical computing


Our experts examine the digital output generated by the computer that scanned the chips after genotyping. The input for the following computational process is this file of A’s, G’s, C’s, and T’s.


We’ll begin with phasing. One chromosome is passed down from the mother and the other from the father in each pair of chromosomes. For each SNP, the genotyping technology that scans your DNA sample reveals which genotypes you acquired from your parents, but it doesn’t tell us which sets of variations you inherited from the same parent. We can use phasing to assist us figure this out. It divides the variations inherited from each of your parents into two categories, one for maternal variations and the other for paternal variations.


The analysts utilize imputation to infer the SNPs we didn’t read in the genotyping assay after phasing. Consider DNA imputing as reading a sentence with some letters missing – there’s a fair probability you’ll be able to guess the missing letters based on context.


SNPs are not read in the same way by all DNA service providers. Before comparing findings, it’s crucial to infer the SNPs that weren’t read to locate DNA matches for people who utilized different DNA firms.


Then we create your Ethnicity Estimate and list of DNA Matches using advanced algorithms. Your variations are compared to models of 42 distinct ethnicities for your Ethnicity Estimate, and we then give a breakdown of which percentages of your DNA match each of the models – results made possible by our Founder Populations Project.


Your DNA segments are compared to everyone else’s in our DNA database to uncover comparable sequences that indicate a specific segment was likely inherited by two or more people from a common ancestor or ancestors for your list of DNA Matches.


We announced significant improvements to our computing method in January.



Steps to come 


Our DNA test and the meticulous method mentioned above were intended to allow everyone to discover more about their ancestors, identify new relatives, confirm established family links, and improve their family history research.


DNA is a precise blueprint of your genetic inheritance that is stored in your body’s cells. By taking a MyHeritage DNA test or uploading DNA findings from another service to MyHeritage for free, you can take advantage of the genealogical tale your DNA reveals.

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