genomic DNA extraction from human blood: a brief introduction

Genomic DNA (gDNA) is found in the chromosomes. It has a higher molecular weight and is longer as compared to plasmid DNA. This is what scientists need and collect when doing genome sequencing.

One purpose of genome sequencing is to help scientists understand how the genome works, and how genes work together to enable growth, development, and maintenance of the entire human body or any other organism. In order for a scientist to be able to study how the genome works, a process by the name genomic DNA extraction has to take place. There are several ways to extract the genomic DNA and from different sources including blood, hair, urine, etc.

How is it done?

There are traditional and modern ways of extracting genomic DNA from the blood. The option a scientist decides to apply depends on the type of equipment available. These include phenol extraction.

Phenol extraction is the process by which a volume of phenol is added to an aqueous soup with the proteins and the DNA to be extracted. Phenol and water cannot mix therefore they form two phases which are aqueous/water and a phenol phase. These phases are thoroughly mixed forcing the phenol into the water forming an emulsion with droplets throughout. Proteins in water are denatured and divided into the phenol.

The DNA, on the other hand, stays in the water. The solution is then centrifuged forcing the phases to separate. The DNA contained in the water phase is then pipetted off while the protein solution discarded. The DNA is then concentrated and de-salted with ethanol precipitation. This method is, however, time-consuming and the reagents can be toxic and endangering to one’s health.

Other similar traditional methods of extraction include isopropanol precipitation, nonorganic solvent extraction, the formamide lysate method, and glass particle adsorption. However, due to their ineffectiveness in extracting genomic DNA from frozen, trace, and dried blood, scientists have ventured into finding better ways to perform the extraction.

Modern extraction methods include non-enzymatic salted out method and microsphere method. These methods are cost effective, less time consuming, and produce an improved quantity of DNA as compared to the traditional means.

Why is it important?

The extraction is valuable in genome sequencing and in studying genetic disorders. With the information obtained from the DNA, it is possible to develop a treatment for a specific patient as well as help with forensic investigations. Like the microsampling revolution in molecular research, it comes down to getting a lot of information from a small amount of material.