A mutation that occurs in one member of a family as a result of a mutation in a germ cell of a parent or in a fertilized egg. For example, there is no history of achondroplasia (q.v.) in 90% of the families that have one child with the condition. In these situations a de novo mutation occurred, and the parents have a very low chance of having a second child with achondroplasia.
Subjects: Genetics and Genomics.