When you hear the term “DNA test,” you might automatically assume that individuals are usually tested to determine paternity or for another legal reason. However, there are actually many different types of DNA tests out there today. Pediatric surgeon use DNA methods for genetic testing, inherited diseases and many more. Whether it’s testing crime scene evidence, identifying the stage of cancer in an individual, or determining if two people share a common ancestor year ago, these types of DNA tests each have their own unique use and significance.
The Different Types of DNA Test:
Y-chromosome (or Y-DNA):
This type of test determines the ancestral history of a male by analyzing his Y-chromosome, which passes from father to son fairly unchanged. This results in a paternal lineage being generated through analysis of this chromosome.
Compare your Y-chromosome markers with other males in a particular surname project or define your deep ancestry by testing all 25 markers and going back as many generations as possible using the Big Tree DNA Comparison tools. Paternal haplogroup predicted from Y-STR values is also included with optional mtDNA tests. The Little More about Y-Chromosomes section on the DNA Fingerprint website provides detailed information about what you can expect from these types of tests.
Mitochondrial (or mtDNA)
This type of test analyzes a person’s mitochondrial DNA, which is passed down from mother to child and does not change throughout generations. During this process, you will have the opportunity to compare your own mtDNA markers with others in a particular surname project or deep ancestral lineages going back about 30 generations using the Family Tree DNA Comparison tools. The Little More about Mt-Chromosomes section on the DNA Fingerprint website provides detailed information about what you can expect from these types of tests.
This type of test uses a person’s autosomal DNA, which is present in all cells and does not include the X or Y chromosomes. Autosomal DNA is used to reveal ancestral lines going back several hundred years by comparing your results with others who have had their DNA tested. You can compare your own results with others who have had their DNA tested at Ancestry by using the Relative Finder feature. The Little More about Autosomes section on the DNA Fingerprint website provides detailed information about what you can expect from these types of tests.
Types DNA Evidence Analysis
Polymerase Chain Reaction (PCR)
This method uses the ability to isolate, amplify (make many copies of), and analyze minuscule amounts of DNA. PCR is used in popular tests like AncestryDNA and 23andMe.
Short Tandem Repeats (STR)
This process uses variations in the lengths of tandem repeats (sequences located at specific places along a chromosome) to estimate how closely related two individuals are. Tandem repeats might look like this: C-A-G, where each letter represents one nucleotide, or building block, of DNA. So if an individual has 17 CAG repeats, it means that they have a specific arrangement of nucleotides 17 times. The more repeats, the more likely two people are to share common ancestors within the past several generations (although there is no exact timeframe given). STR testing has become less popular as companies like 23andMe and Ancestry use autosomal DNA.
This process establishes the ancestral history of a male’s paternal line by testing for specific markers on his Y chromosome. These tests are also known as Y-DNA haplogroup tests. The results will identify the individual’s paternal lineage and which group of people he belongs to around the world.
Mitochondrial DNA (mtDNA)
This process establishes the ancestral history of a female’s maternal line by testing for specific markers on her mitochondrial DNA. These tests are also known as mtDNA haplogroup tests. The results will identify the individual’s maternal lineage and which group of people she belongs to around the world.
How it is done?
Getting a DNA sample is easy. You can use a cotton swab on the inside of your cheek for a saliva test or a blood sample from a simple prick of your finger for a blood test.
Most tests require you to send in a cheek swab or smear of blood. Some tests, such as Family Finder and My Heritage, also accept buccal (mouth) swabs. Family Tree DNA accepts saliva samples for males but not females.
Once your sample is received by the testing company, it will be processed and analyzed. All DNA samples are stored, usually for an indefinite amount of time, in case you or your child wants to test with another company at a later date.
Differences in DNA test results for males and females?
Some Y-DNA tests, such as the Family Finder DNA Test, do not provide mtDNA (female) results. Other companies like 23andMe provides both mtDNA (female) and autosomal (both sexes) results.
Male/female comparisons are possible but not usual. Most companies only compare same-sex siblings, cousins, parents/children or opposite sexes to establish family connections.
Possible Advantages and Disadvantages of DNA Testing
Advantages: The most obvious advantage is that it can help provide information regarding your ethnic background or lineage that would otherwise be difficult to find through traditional research methods.
Disadvantages: Since science can’t pinpoint exactly when each element of DNA was passed to you, it’s possible that the results will show an incorrect relationship due to a false positive or false negative. It’s also important to note that your results are not meant for genealogical purposes unless specifically indicated by the company.