Pedigree Analysis

A pedigree is made to give an overview of the inheritance pattern and frequency of a (suspected) hereditary trait. Each family member is represented by a symbol: circle (female) or square (male), which is filled or black for affected individuals and empty or white for normal individuals. Mating is illustrated by a connecting horizontal mating line, their offspring is depicted beneath a vertical offspring line, and siblings are attached to a horizontal sibship line. Each generation is assigned a Roman numeral (I, II, III etc.) and each individual of a generation is assigned an Arabic numeral (1, 2, 3 etc.).

Figure 1: Explanation for pedigree symbols

A proband is the individual who is the first affected family member who seeks medical attention regarding this phenotype (disease). Among the older generations from this family, there may have been other affected members; however, the proband typically refers to the member seeking medical attention or being studied, even if affected ancestors are known.