According to this article:

Gene mutations can be classified in two major ways:

  • Hereditary mutations are inherited from a parent and are present throughout a person’s life in virtually every cell in the body. ...

  • Acquired (or somatic) mutations occur at some time during a person’s life and are present only in certain cells, not in every cell in the body. These changes can be caused by environmental factors such as ultraviolet radiation from the sun, or can occur if a mistake is made as DNA copies itself during cell division. Acquired mutations in somatic cells (cells other than sperm and egg cells) cannot be passed on to the next generation.

The "random mutations in genes" appear to be called Somatic mutations. For the context of this question, these are the mutations I am asking about (not the hereditary mutations).

My question: Is it possible for there to be a random un-mutation of genes? Some sort of reverse-somatic mutation. If so, have there been any clinically proven instances of it?

After-thought: Or is it all a Somatic mutation, aka you can experience a mutation that makes you more susceptible to a particular disease, then another mutation that makes you less susceptible to the same disease... so not necessarily a reverse mutation, but a 'forward' mutation that negates the original ill effect of the first mutation.

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    $\begingroup$ Of course a mutation can revert back to its old state via random mutagenesis (un-mutation as you call it). Nobody has kept a track of it I guess but it is not such an uncommon thing. But think of its probability; it would be low (just a simple calculation). You may also want to look at PAM matrices. $\endgroup$
    Jul 12, 2016 at 18:29

1 Answer 1


A large part of the body of your question seems relatively unrelated to the main question which is a little confusing. I will focus on the question

Is it possible for there to be a random un-mutation of genes?

Yes, these are usually called reversed mutation. It is quite common though that a second mutation at a distinct locus may reverse the phenotypic effect of a first mutation. This is called a compensatory mutation.


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