Is tunneling of a proton in our DNA a cause of mutations?
Keto-enol tautomerism involving proton transfer within a single DNA base can lead to mispairing and mutation during replication.  This is touched on in the previous citation provided by tsttst as well as this section from An Introduction to Genetic Analysis. 7th edition: https://www.ncbi.nlm.nih.gov/books/NBK21897/  I have not found a clear statement of whether the proton transfer is over sufficient distance to constitute "tunneling".