This twitter thread gives some figures from the paper which is behind a paywall
This is the paper:
https://www.cell.com/trends/molecular-medicine/fulltext/S1471-4914(23)00072-2#%20
This shows how rare mutations are in DNA given the number of base pairs:
“Germline mutation rate:
~1 × 10-8 per base pair per generation.
Somatic mutation rate:
0.3 × 10-6 to 3 × 10-6 per base pair
(10 to 100x the germline rate)”
I have been thinking about this and one thought is that germline cells are generally quite quiescent so it is not surprising if their DNA has fewer mutations in it. I don’t think it is necessarily a better repair system.
Highest mutation rate tissue = liver.
This study
in Figure 3 shows “age-dependent increases of mutant frequencies in 12 different tissues in Muta mice”, and shows that the mutation rate in the colon and small intestines is far and away higher than in all the other 10 tissues. Muta mice are (from Google search) “a transgenic mouse model used for in vivo mutation studies. Specifically, it contains a lambda phage vector with a lacZ gene (a reporter gene) integrated into its genome. This allows researchers to assess the mutagenic effects of various chemicals and other agents by examining the frequency of mutations in the lacZ gene in different tissues.”
Perhaps the high rate of mutations in these tissues (small intestines and colon) is due to the high turnover rate of cells in these organs.