Pedigrees

A pedigree is a diagram of a family history that shows relationships between family members and their status with respect to a particular hereditary condition. The index case, or affected person through which the pedigree is discovered, is called the proband and is indicated by an arrow on pedigrees. Males are denoted by squares and females by circles. A filled symbol indicates that an individual is affected by a specific condition. Generations are represented on horizontal levels; parents on one level and the children of those parents together on a level below them. The following diagram shows some of the standard symbols used in pedigrees.

Sample Pedigrees

In this family, the father is affected as is the first born daughter. The mother, son and twin girls are not affected. This couple is pregnant with another child.

This pedigree shows three generations. The proband is the affected woman in the second generation. Her father (now deceased) had the disease, her mother is unaffected and still living. She has two siblings; neither is affected. She has three children from a previous marriage, two are affected and she is currently pregnant with a new partner.

	In this family, the father is affected as is the first born daughter. The mother, son and twin girls are not affected. This couple is pregnant with another child.

	This pedigree shows three generations. The proband is the affected woman in the second generation. Her father (now deceased) had the disease, her mother is unaffected and still living. She has two siblings; neither is affected. She has three children from a previous marriage, two are affected and she is currently pregnant with a new partner.