Our fertility clinic has informed us that our egg donor has a mutation of the DUOX2 gene. My husband does not. Is this mutation clinically significant? What follow-up information do I need to ask for? Should I request another donor?

Yes. it is clinically significant. 1 mutation is milder than 2. but this is a situation where 1 mutation can cause a problem. so either find a new donor or meet with a genetic counselor to decide whether to use her. it does not mean she cannot be used you just need to be counseled.
Follow up. Consider scheduling a Virtual visit with one of the HEALTHTAP genetic specialists or with one of our Fertility specialists. They will be able to provide more comprehensive information on the less common genetic mutations that can be detected through preimplantation genetic testing.