Just curious. I think that there should be DNA in my fingernail clippings or hair, so I’m wondering why I just went through the process of spitting into a tube to give Ancestry.com a DNA sample. Is it lesser DNA in the clippings or hair? Or is there no useable DNA there at all? It would be far more efficient to send DNA samples that aren’t in liquid form at all, seems to me, but what do I know?*
*answer: very little
Yes, hair and nails contain DNA. I think it’s just easier for the lab to extract it from saliva.
Agree. We watch A LOT of crime shows. Many people get convicted (due in part) on hair DNA.
Yes, DNA is found in lots of sources, though quantity/quality and ease of extraction vary a lot still, as do contamination concerns. If nothing else some sources are more favoured simply because the lab extraction technique has been ironed out and is available to perform in a McDonald’s burger line-style, rather than like a from-scratch custom chef-made burger that starts with a trip to the local market at 5am for ingredients.
I was part of an environmental DNA collection project on a northern lake last summer, and much of the work involved avoiding contamination of the water samples with other DNA . A sealed swab that’s opened up, stuck in your mouth, then sealed up again 5 seconds later should have mostly just your cheek cells, whereas your fingernail clippings may have DNA from everything you touched/scratched for the past week plus whatever weird fungus is growing under your nails.
The shaft of a hair is made up of of keratin, which is dead matter and not living cells; it therefore does not contain DNA. But a hair that falls out or is plucked will usually have its follicle still attached to it, and the follicle does contain DNA because it’s made up of live cells.
Here is an article regarding fingernail clippings for DNA analysis:
This isn’t correct; from this source:
“over the past 2 decades scientists have demonstrated that, although there is a clear difference in quality of DNA recoverable from the root (high quality) versus non-root components (poor quality) of hair and nail, within limits, PCR amplifiable mitochondrial (mtDNA) and nuclear DNA (nuDNA) can be retrieved from almost all sources of ‘fresh’ (i.e. not historic/ancient) hair, including from the human head, eyebrow, pubic and torso hair (e.g. Baker et al., 2001), and nail (e.g. Tahir and Watson, 1995, Anderson et al., 1999, Cline et al., 2003).”
It’s not that there isn’t DNA in a hair shaft or nail clippings (there is), it’s just that it’s so much more concentrated and higher quality in other sources, which is where earlier lab techniques focused. We’ve gotten better at extracting the lower quality sources over the years.