Pedigree

A pedigree tree is a diagram depicting members of a family, their inter-relations, and their disease or phenotypic status. It provides an overview of the inheritance pattern and frequency of a specific trait.

Each family member is represented by a symbol: circles for females and squares for males. Filled symbols represent affected individuals, and empty ones represent normal individuals. Matings are illustrated by connecting horizontal lines, while their offspring is depicted beneath. Each generation is assigned a Roman number (e.g. I, II, III) while individuals of a generation are assigned Arabic numbers (e.g. 1, 2, 3).

Figure 1: Pedigree illustrating a three generation family and the inheritance of an X-linked recessive trait.