Family trees

• Doctors can use a pedigree analysis chart to show how genetic disorders are inherited in a family
• Pedigree analysis is usually undertaken if families are referred to a genetic counsellor following the birth of an affected child
• The pedigree analysis diagram is used to show the relationship within an extended family
• Males are indicated by square shapes and females are represented by circles
• Affected individuals are red and unaffected are blue
• Horizontal lines between males and females show that they have produced children
• This analysis shows both male and female are affected, and every generation has affected individuals
• One family group has no affected parents or children, but the remaining two families have one affected parent and affected children too