Biology & How to Do a Pedigree Chart

Genetic pedigrees track genes, mutations and diseases in families.

In biology, you can track genes throughout families using pedigree charts. Unlike family trees, pedigree charts do not simply show personal information on members of the family. They show information on how a specific gene affects each member of the family. You can make a pedigree chart if you know how a gene affects each member of the family included in the chart.

Instructions

1. Establish a key for your pedigree chart. You will need different shapes for men and women. You will also need to show what different colors and shades represent on your chart. Usually people who are affected by a gene are shaded one color, people who are carriers of a gene are shaded another color or partially colored and people who are unaffected by a gene are left empty.

2. Put the shapes that represent the eldest members of the family at the top of the chart. If these eldest members are married or had children together, connect them with a horizontal line.

3. Insert the shapes of each generation below the shapes for the previous generation. When people in the family have children, draw the shapes of their mates next to them and connect these two people with a horizontal line. Under these two parents, make a long horizontal line with branching vertical lines for each of the children. Insert the shapes for the children at the bottom of the branching lines. Connect this horizontal line with the horizontal line that connects the parents.

4. Shade in the shapes based on how the gene affects each of the family members. Use the key that you established in Step 1 to do this.

References

• Biotopics: Genetic Pedigree
• North Dakota State University: Mendelian Genetics
• Howard Hughes Medical Institute: Pedigree Analysis