Symbol Guide for Pedigree Charts

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Pedigree charts are a visual tool for documenting biological relationships in families and the presence of disorders. Using these charts, a medical professional such as a geneticist or genetic counselor, can analyze the genetic risk in a family for a particular trait or condition by tracking which individuals have the disorder and determining how it is inherited.

A standard set of symbols has been established for use in creating pedigree charts. Those found within the body of several entries in the encyclopedia follow the symbol guide explained on the next page. The exact style and amount of information presented on the chart varies for each family and depends on the trait or condition under investigation. Typically, only data that is directly related to the disorder being analyzed will be included.