A gene mutation is a permanent change in the DNA sequence that makes up a gene. Gene mutations occur in two ways:

1. Hereditary mutations are inherited from a parent, are present from birth, and are passed on to the next generation.
2. Acquired mutations spontaneously develop during a person’s lifetime, may be present at birth if it occurred prenatally, and may be passed on to the next generation only if the mutation affects the egg or sperm.