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Instructions on How to Draw a Pedigree

Begin by drawing a solid square (male) or circle (female) for the first person with disease who presented to medical attention. This individual is called the proband. Place an arrow on the lower left corner of this individual to indicate he/she is the proband.

Write the person's first name, or initials below the symbol.

Write the person's current age below the symbol.

Indicate the disease or disorder the individual has along with the age of onset below the symbol.

Next, draw the person’s parents. To indicate partners/marriage draw a horizontal line connecting the two symbols (see below). If the individuals are consanguineous (i.e. related) indicate consanguinity with a double horizontal line. If the degree of consanguinity is not clear on the pedigree, please write above the relationship line, i.e. “2nd cousins.”

Add the parents current age, or age at death (d. age or year) with cause of death. Also, indicate any diagnoses (dx. Disease X) the individuals may have along with the age at diagnosis (dx. Disease X 50y.o.).

Draw any siblings in birth order from left (oldest) to right (youngest). Siblings are connected by a horizontal line above the symbols, with vertical lines connecting the symbols to the horizontal line. Leave space to add any partners and children.

Add aunts, uncles, grandparents in the same manner. All affected individuals should be included in the pedigree and as many unaffected individuals as possible (parents, grandparents, and siblings of any affected individual).

For each individual add the following below their symbol

  • Initials or generation number
  • Current age (if known)
  • Any diagnoses the individual has received along with the age of onset of the disorder.
  • An asterisk (*) next to individuals willing to participate in the study.

** The current place of residence (City, State) for each individual willing to participate in the study can be recorded on the pedigree, or must be provided to the IIHG as a separate list.

At the top of the pedigree write the ethnicity of each grandparent. Record the date the pedigree was obtained.

Finally, draw a key in the lower left corner indicating what the shading represents.