Buccal Swabs: A Complete Guide to Collecting & Analyzing DNA
Buccal swabs, also known as buccal smears, are a method of collecting DNA from the cells on the inside of a person's cheek. The word "buccal" refers to the cheek or mouth area. To perform a buccal swab, a healthcare provider gently rubs a small sponge or brush (swab) against the inside of the cheek to collect buccal epithelial cells. This is a relatively non-invasive way to collect DNA samples for genetic testing or forensic analysis.
Buccal swab collection kits typically contain cotton, foam, or flocked swabs, collection tubes, gloves, labels, and instructions. The inside of the cheek is swabbed and rubbed for 5-10 seconds to collect cells, taking care not to touch the swab tip to any surface besides the inner cheek. The swab is then placed in a collection tube, allowed to air dry, and labeled. Buccal swab collection can be done by a healthcare provider or by the individual themselves following simple instructions. It is fast, painless, and collects high quality DNA.
Buccal swabs are commonly used for DNA-based testing and analysis in clinical, forensic, and research settings. In the clinic, buccal swabs provide DNA for genetic tests such as newborn screening, paternity testing, oncology risk testing, and pharmacogenetic testing. They are easy to collect from adults and children of any age. In forensics, touch DNA from buccal swabs can include or exclude suspects when matched to DNA collected from a crime scene. Buccal swabs are also widely used in biomedical research studies involving genetics, epigenetics, gene expression, and proteomics.
The high quality DNA collected by buccal swabs is compatible with a wide range of downstream applications including PCR, microarrays, sequencing, genotyping, and mass spectrometry. Compared to blood samples, buccal swabs provide more pure epithelial cell DNA with lower leukocyte contamination. The intact, high molecular weight DNA isolated from buccal swabs performs excellently in techniques like long-range PCR.
Buccal swabs have many advantages that make them a preferred method for collecting DNA samples:
The non-invasive nature, convenience, and excellent DNA yields make buccal swabs the preferred method for most DNA collection applications.
While buccal swabs are widely used, researchers often have to choose between buccal swabs, blood, saliva, or other DNA sources. Key factors that distinguish buccal swabs include:
For most applications, the epithelial cell purity, excellent DNA quality, stability, and subject comfort make buccal swabs the preferred choice over blood or saliva for collecting DNA samples. However, saliva may be preferred for studies involving proteomics or metabolites.
While buccal swabs provide high quality DNA, some precautions must be taken to maximize DNA yield and purity:
Following best practices for buccal swab collection, handling, and processing ensures maximum DNA purity and yields for downstream analysis.
Two main approaches are used for DNA extraction and purification from buccal swabs:
Traditional DNA extraction kits utilize proteinase K digestion followed by alcohol precipitation or column absorption to isolate DNA. While effective, these kits involve multiple tubes and steps.
Newer kits use novel solid-phase chemistry to extract DNA in a single step directly from swabs, reducing hands-on time and plastic waste. For example, Echoloation extraction technology lyses cells and binds DNA to a matrix in one step, eliminating the need for hazardous chaotropes.
In both traditional and novel kits, purified DNA is eluted into a low salt buffer compatible with downstream applications like PCR and sequencing. Choosing optimized DNA purification strategies maximizes DNA yield and quality from buccal swabs.
Pharmacogenetic testing analyzes how genetic differences impact drug response, allowing for individualized medicine. Buccal swabs provide a convenient DNA source for pharmacogenetic tests. For example, testing for HLA-B*57:01 uses buccal swab DNA to screen for hypersensitivity to the HIV drug abacavir. Additional pharmacogenetic tests screen for warfarin sensitivity, opioid metabolism, and risk of carbamazepine adverse effects using buccal swab DNA samples. The non-invasive collection and excellent DNA makes buccal swabs an ideal choice over blood for pharmacogenetic analyses.
Buccal swabs are widely used in biomedical research, but some factors should be considered:
Accounting for cellular heterogeneity, optimizing collection and stabilization methods, and choosing effective DNA purification strategies allows buccal swabs to provide high quality DNA for diverse research applications.
Buccal swabs provide a simple, non-invasive way to collect high quality DNA samples. Their excellent DNA purity and yields make buccal swabs ideal for diverse genetic, epigenetic, forensic, pharmacogenetic, and biomedical research applications. Following optimized buccal swab collection and processing protocols allows researchers and clinicians to easily obtain DNA samples for precise, personalized analysis and treatment.
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