If an acquired mutation occurs in an egg or sperm cell, it can be passed down to the individual's offspring. Once an acquired mutation is passed down, it is a hereditary mutation. Acquired mutations are not passed down if they occur in the somatic cells, meaning body cells other than sperm cells and egg cells.

What is the difference between acquired and inherited mutations?

Inherited mutations are thought to be a direct cause of only a small fraction of cancers. An acquired mutation is not present in the zygote, but is acquired some time later in life. It occurs in one cell, and then is passed on to any new cells that are the offspring of that cell.

Which mutations are heritable?

Hereditary mutations include cystic fibrosis, hemophilia, and sickle cell disease. Other mutations can happen on their own during a person's life. These are called sporadic, spontaneous, or new mutations. They affect only some cells.