It seems to exist. Not clear there is a lot of evidence it's relevant. If you sequence a tissue that has cancer or some other disease that causes increased cell

It seems to exist. Not clear there is a lot of evidence it's relevant. If you sequence a tissue that has cancer or some other disease that causes increased cell division, you will see more somatic variation. Not sure why this is particularly surprising or interesting. It's been known for a while now. If somatic variation was important for brain development or function (like it is in the adaptive immune system), that indeed would be super surprising, but that's not what I'm seeing here.