A mutation is often thought of as a bad thing, especially one that stops a protein from being made. Every once in a while, however, we hear a story that reminds us that mutations (changes in our DNA sequence) are not necessarily good or bad. ~20% of us are walking around with two ‘defective’ copies of the FUT2 gene (where ‘defective’ means that these copies make no FUT2 protein). Interestingly, these people are more resistant to norovirus infection, a common cause of the stomach flu.
Here is a link to a great blog post from Madeleine Price Ball for more details.