Understanding a pedigree

Doctors can use a pedigree to show how genetic disorders are inherited in a family. They can use this to work out the probability that someone in a family will inherit a condition.

In order to understand the following presentations on inheritance patterns, you may find it useful to spend a few moments looking at the images below and familiarising yourselves with the meanings of the symbols and connecting lines used to draw pedigrees.

Please note - this table is best viewed in landscape mode when viewing this step on a mobile device.

Symbol	Description	Meaning
	Square	Male
	Circle	Female
	Diamond	Gender unknown
	Line above	Siblings
	Angled lines above	Twins
	Line between	Partners
	Two lines between	Consanguineous couple
	Line down	Children
	Shaded	Affected individual
	A small circle inside a larger circle/square	Carrier
	Line diagonally through symbol	Individual is deceased

Once you have seen some examples, you may wish to draw your own family pedigree and see the results.