At-home DNA testing is a popular method for individuals seeking insights into their genetic makeup, whether for ancestry, health, or relationship verification. While various sample types can be used, hair often comes to mind as a convenient source. This article explores the process of using hair for at-home DNA testing, from understanding its biological suitability to collection and analysis, along with important considerations.
Hair as a DNA Source
Hair can be a source of DNA, but it is important to distinguish between the hair shaft and the hair follicle (root). The hair shaft, the visible part, primarily consists of keratin. While it contains mitochondrial DNA (mtDNA), nuclear DNA, used for comprehensive genetic analysis and relationship testing, is found in the nucleated cells of the hair follicle. Therefore, a hair strand must have the root or follicle attached to yield sufficient nuclear DNA for testing. Plucked hairs, unlike shed or cut hairs, are more likely to retain this crucial follicle, which appears as a tiny, translucent bulb at the end of a plucked strand.
Collecting Hair Samples
Proper collection of hair samples is important for successful DNA testing. Hair should be plucked, not cut, as cutting removes the DNA-rich root. The goal is to obtain hair strands with the visible follicle attached. A DNA testing lab typically requires 5 to 10 strands with intact roots, though some may suggest 25-50 for increased success.
Use tweezers or a clean comb to firmly pull hair directly from the scalp or body to ensure the root is secured. Place each sample into a separate, clean, dry paper envelope, avoiding plastic bags which can trap moisture and degrade the sample. Handle the hair strands as little as possible to prevent contamination.
After Sample Collection
Once collected, hair samples are sent to a specialized laboratory for analysis. Most at-home DNA testing kits include prepaid shipping materials and instructions for mailing. Upon arrival, the lab begins DNA extraction, isolating genetic material from the hair follicles.
Following extraction, the DNA is amplified using Polymerase Chain Reaction (PCR) to create millions of copies for easier analysis. The amplified DNA is then analyzed to generate a genetic profile, used for ancestry tracing or confirming biological relationships. Results typically arrive within a few business days to a few weeks after receiving the sample.
Key Considerations for Hair DNA Testing
While using hair for DNA testing offers convenience, several factors impact the success and reliability of results. The primary challenge is obtaining sufficient quantity and quality of nuclear DNA from hair. Hair samples, even with follicles, contain less DNA compared to cheek swabs, which laboratories generally prefer for their higher DNA yield and quality.
Hair samples are also more susceptible to degradation and contamination. Environmental factors like heat and humidity can break down DNA, and improper handling can introduce foreign DNA, potentially leading to inconclusive or inaccurate results. Reputable testing services will state requirements for hair samples and may have a lower success rate for hair compared to buccal swabs, with some reporting 80-90% extraction success if the hair has viable DNA. It is advisable to choose a testing service that is transparent about their methods and success rates for hair samples.