The authors are answering questions about this paper on reddit. (5 Oct)<p>"tl;dr Mutations are happening in your neurons every day! We looked at individual neurons to find out how many.<p>We will be back at 2 pm ET (11 am PT, 6 pm UTC) to answer your questions, ask us anything!"<p><a href="https://www.reddit.com/r/science/comments/3nkdj5/science_ama_series_we_are_mollie_woodworth_and/" rel="nofollow">https://www.reddit.com/r/science/comments/3nkdj5/science_ama...</a>
I think a lot of the mutations can be attributed to infidelities of single cell sequecing. The amplification of DNA that has to be done has a tendency to incorparate errors. If you start with a single copy of DNA then an copy error early in amplification will look like a mutation.
The neuron data is compared to non-single cell sequencing of heart cells.
Assuming those mutations have effects on neurons functions (and not e.g. just remnants from ontogenesis) seems this should make future "immortality" tech much more difficult (post-cryonics resurrections, brain uploads, etc).<p>Not enough to scan brain connectivity info, neuron types and per-person genome, you will now also need per-neuron genomes to truly capture and reproduce a brain.<p>Not that we were anywhere close to any sorts of brain uploading, but this news just made it orders of magnitude more difficult.
I wonder if this is related to neurite repulsion. In Drosophla, the DSCAM gene is alternatively spliced to provide an "expression signature" for each neuron so they can maintain neurite repulsion. Maybe these point mutations are providing a similar function?
Is that related to the fact that neurons have much longer lifespan than most of other cells in human body? How many mutations connective tissue cells have for example? Hard to say whether 1000 is much or not without knowing about other parts.
Given that this was whole-genome sequencing, is 1700 mutations higher than other tissues? The paper doesn't appear to say that.<p>If they were claiming that this were an unusually high mutation rate, I'd wonder why everyone doesn't die of brain cancer. If other tissue had N mutations per genome, and cancer typically takes 10 mutations to create, in the absence of compensatory mechanisms, the ratio of brain cancer to other cancers should be about (1700 choose 10) / 50 * (N choose 10). If N were, say, 100, that number would be so large that not one person would ever had developed any cancer other than brain cancer.
Are you sure you're not counting mitochondrial DNA mutations? A single neuron has about 1000 mitochondria, and would easily have tens of thousands of unique mitochondrial mutations.