With the increasing popularity of ancestry and genetic genealogy testing, DNA extraction kits have become widely available for personal use. These kits allow anyone to isolate their own DNA from a simple at-home sample collection. DNA collected through an extraction kit can then be used for a variety of genetic testing services. This article provides an overview of DNA extraction kits, how they work, and what you can do with your extracted DNA.
What is DNA Extraction?
DNA extraction, also known as DNA isolation, is the process of separating DNA molecules from other cellular components like proteins and RNA. In living organisms, DNA is found within the nucleus of cells, wrapped around histone proteins. Extraction ruptures the cell membranes to release the nuclear material and uses chemical methods to separate DNA from other molecules.
How Do Commercial DNA Extraction Kits Work?
Most at-home DNA extraction kits employ saliva or cheek swab samples for ease of collection. The samples are placed in a lysis buffer solution containing detergents that break open cell membranes and dissolve cellular components. The solution and sample are then heated to help release DNA. Another solution containing alcohol is added to precipitate or solidify the DNA so it can be easily collected. The precipitated DNA is drawn up into a small collection vial where it can dry and be shipped to a testing laboratory for analysis. The entire extraction process takes only a few simple steps and around 30-45 minutes.
Types of DNA Extraction Kits
There are a few different types of DNA extraction kits on the market for home and personal use:
- Saliva Collection Kits: Saliva is the most common sample type for home DNA extraction due to its non-invasive collection via spit or oral swab. Saliva contains nucleated cells from the inside of the cheeks that are rich in DNA.
- Cheek Swab kits: Similar to saliva kits but involve gently scraping the inside of the cheek to collect epithelial cells. Some find swabbing less messy than spitting.
- FTDA Extraction Kits: Allow for extraction of DNA from other sample types like hair follicles or dried blood spots using specialized buffers and techniques.
- Rapid DNA kits: Contain consumable instruments that fully automate the extraction process from sample to DNA for labs or law enforcement processing larger sample volumes.
What Can You Do With Extracted DNA?
The main use of personal DNA extraction is to provide samples for genetic and ancestry testing services. Popular options include:
- Ancestry Composition: Estimates ancestral percentages through comparisons to reference populations worldwide. Good for exploring ethnic heritage.
- Family Tree DNA: Tests for genetic matches to potentially identify relatives through comparison to their large customer database.
- Health Reports: Analyze DNA for increased risks of certain diseases and health conditions, helping with medical screening choices.
- Paternity Testing: Compare a child's DNA profile to alleged parents to determine biological relationships with over 99% accuracy.
- Genealogical DNA Testing: Specialized tests analyze particular genetic regions predictive of ancestral origins to narrow down ancestral hometowns or regions.
Beyond ancestral and health insights, personal DNA could eventually have applications in forensic genealogy for identifying unknown remains, tracking hereditary diseases in families, or resolving disputed estates and inheritances involving questions of family relationships.
Tips for Successful DNA Extraction
To ensure the best quality extracted DNA sample for downstream use, it's important to follow the kit instructions carefully:
- Provide an adequate sample amount (1-2ml saliva or swabs of both cheeks).
- Avoid eating, drinking, smoking or brushing teeth before collection for 30 minutes.
- Store samples at room temperature until ready to extract to prevent DNA degradation.
- Gently invert solution tubes during heating/cooling steps without shaking or vortexing.
- Seal and pack tubes securely for shipment according to kit directions.
Common Challenges and Considerations
Some potential issues that could impact DNA extraction include:
- Low DNA yield from small or degraded samples requiring re-collection.
- Inhibitors co-extracted with DNA that interfere with subsequent analysis. This can give inconclusive results.
- DNA fragmentation during handling that diminishes matching power for ancestral origins.
- Legal/ethical issues around privacy, access to results and responsible use of personal genetic information.
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