This pedigree was published in The Journal of the American Medical Association and shows a family with a known BRCA1 mutation. In this extended pedigree, it is obvious that this family has a strong inherited tendency to develop breast and ovarian cancer. But each of the small families branching off has their own story to tell. Family 1 First, look at the family in the middle. Cancer occurs at a young age.
Cancer occurs in several generations.
The mother had breast cancer at the age of 45, one daughter had breast cancer at age 30, another daughter had breast cancer at age 38. With only this information, it would be relatively easy to identify this as a hereditary breast cancer family. If this was the only information we had, it might be difficult to identify this as a breast cancer family. However, when you extend the pedigree to find the other cancers in the cousins and aunt, it becomes apparent that the father in this family is a carrier of the BRCA1 mutation and has passed it on to his daughters. The family on the left shows a daughter who had breast cancer at the age of 28 and ovarian cancer at the age of 33.