Extracting DNA from blood sounds like a forensic practice you'd see on TV, but what's the point? How is DNA extracted? While blood is one of the most common samples used for DNA extraction, there are other sources from which DNA can be obtained.
What is DNA?
To begin, let's cover what DNA is and its role in the human body. The abbreviation DNA stands for deoxyribonucleic acid, a complex molecule. This is the fundamental component of an individual's entire genetic makeup. DNA contains the instructions necessary to create and maintain life.
These instructions are written in a code with four letters that correspond to four molecules: Adenine (A), Thymine (T), Cytosine (C) and Guanine (G), which join in a specific way, A joins with T and C with G, forming a double helix or spiral staircase.
The complete DNA sequence is called the genome. This is essentially our genetic code. Every cell in our body, with few exceptions, contains a copy of our entire genome. You could imagine DNA as a single, long molecule that is free within the cells of our body, but it is always found in the cell nucleus and is also tightly bound to specific proteins.
Interestingly, although we all have very different characteristics among us, and it is our particular genetic code that determines our individual traits, most of the DNA (99,9%) is the same in all human beings.
Differences between somatic and germline DNA
It is important to differentiate between somatic DNA and germline DNA. During embryogenesis, all human beings are formed from the union of an egg and a sperm. The genome of the new living being will be made up of part of the mother's and father's DNA, and all the cells that arise from the zygote will have the same genetic material known as germline DNA. As we age, tissues may acquire certain genetic variations or mutations that are not present in the rest of the body. Therefore, when we obtain a sample of a specific tissue and analyze its genetic material, this is known as... Somatic DNA. This is why there can be small differences between somatic and germline DNA.
Function of DNA: our genetic code
We could define our genetic code as our life's blueprint. This means that DNA contains all the essential information necessary for our growth, reproduction, and health. Furthermore, although every cell carries the same information, depending on its type, the specific information required for each cell—from neurons to muscle cells—will be activated. Finally, DNA determines our defining characteristics, from our eye color to our love of sweets or whether we are predisposed to certain injuries or diseases.
Looking at all these types of information contained in DNA, it's easy to see its relevance for study. Any change within the DNA sequence can lead to potential diseases, vulnerabilities, or genetic traits, depending on the type of genetic variation.
Can DNA be extracted from blood?
So far, we've seen that DNA is present in virtually every cell in our body. Consequently, DNA can be extracted from blood; in fact, this is one of the most commonly used sources for DNA testing. However, leukocytes are the only blood cells that have a nucleus and, therefore, the only ones that actually contain DNA. Thus, extracting DNA from blood means specifically analyzing the DNA contained within leukocytes.
How is DNA extraction performed?
The first step is obtaining a blood sample, which requires a qualified person or phlebotomist to perform the puncture. It is a minimally invasive procedure. Once the blood sample arrives at the laboratory, technicians will process it to obtain purified DNA. This requires many devices and machines, as well as many reagents. The blood sample is homogenized by inversion—in other words, by turning the blood collection tube upside down to obtain a uniform sample. Once homogenized, the DNA is extracted. As you probably know, within cells we can find many different organelles and structures that need to be removed to purify the DNA. To do this, we need to lyse the cell, which means breaking down all the membranes, and then add a reagent called protease to remove all the proteins. Finally, after all these processes, we will have our isolated DNA.
Today, there are devices and machines that allow the entire process to be automated, meaning you can introduce the blood sample into the system and obtain the isolated DNA sample.
Why use blood to extract DNA?
When it comes to genetic testing, blood is an easily accessible resource, with a simple venipuncture yielding a plentiful amount of DNA, usually of high quality. Once blood has been drawn, it is recommended to perform the tests as soon as possible to prevent the cells and DNA from deteriorating.
Saliva as another source of DNA
In recent years, saliva has been widely used for genetic testing. It can be easily obtained by inserting a cotton swab into the mouth and wiping it across the cheeks, or by collecting saliva. The advantage of using saliva is that it allows for self-collection; there is no need for a trained professional to take the sample. It is a relatively quick procedure, and the sample can be stored at room temperature for longer periods.
Other sources of DNA
Apart from blood and saliva, there are other sources of DNA that can be used in different circumstances:
- SpermA specific analysis is performed to check male fertility, including DNA fragmentation.
- FabricsIn some cases, a patient may be referred for a specific tissue biopsy. This can occur when a tumor is found and a genetic analysis is carried out to check for a mutation in the genetic material, which in this case would be somatic DNA.
- Amniotic fluid or chorionic villiThese types of samples are used in prenatal diagnosis when a suspected genetic condition is identified during pregnancy, to analyze the genetic material of the fetus.
- Hair root: It is mainly used for forensic analysis and paternity testing.
The importance of DNA and genetic testing
Since our DNA contains all our essential genetic information, extracting and studying it can yield a wealth of important data about our health, genetic predispositions, and more. Today, there are many uses for a DNA sample, including:
- It helps diagnose genetic diseases when a person already has signs and symptoms.
- Identifying our risk of certain diseases and helping us take preventive measures to avoid their onset or to detect them as early as possible.
- Prenatal diagnosis is used when a suspected genetic condition is identified during pregnancy. In this case, the DNA sample is obtained from the amniotic fluid or chorionic villi.
- Non-invasive prenatal detection using a sample of the mother's blood; current technology allows analysis of cell-free fetal DNA present in maternal blood.
- Establish carrier status to find out if we are carriers of a disease that can be passed on to our offspring.
- It helps us understand how our body reacts to medications for more effective treatment and to avoid drug reactions.
- It helps to understand our predisposition to certain multifactorial diseases.
Extracting and analyzing DNA from blood or other sources can be extremely beneficial for understanding our genetic makeup, our health predispositions, and more. Since DNA is the instruction manual for life, having access to this data can prevent serious diseases from developing or detect them in their early stages and can help us better understand our path through life.
At Zogen, we understand the importance of DNA, which is why we offer a range of genetic studies, from preventative medicine to prenatal diagnosis. We're expanding the use of genetic services beyond diagnosis, always providing support through genetic counseling consultations with medical geneticists. If you'd like more information about our services, please don't hesitate to contact us. Get in touch with us.
