How mutations are inherited
Men and women can pass an inherited gene mutation to their sons or daughters through their sperm or eggs. When a person with a gene mutation has children, each child has a 50 percent chance of inheriting the same mutation.
Genetics experts look carefully at a family’s medical history for signs of hereditary cancer. You can assist them by gathering medical information from relatives on both sides of your family.
Typically, a genetics expert will look at three or more generations of a family’s medical history to help predict whether family members are likely to have an inherited mutation. They will use this information to create a medical family tree known as a pedigree.
Degrees of relatedness
When speaking about a family tree, experts use the term “degree of relatedness” to describe how closely related one family member is to another. "First-degree relatives” share half of their DNA. If a person has an inherited mutation, each of their first degree relatives have a 50 percent chance of testing positive for the same mutation. Second-degree relatives share one fourth of their DNA, third-degree relatives share one eigth of their DNA, and so on.
- First-degree relatives
- Second-degree relativesHalf-siblings
- Uncles and aunts
- Nieces and nephews
- Third-degree relatives
- Great grandparents
- Great-aunts and Great-uncles