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Genetics and genomics for healthcare www.geneticseducation.nhs.uk © 2013 NHS National Genetics and Genomics Education Centre How to draw a family history.

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Presentation on theme: "Genetics and genomics for healthcare www.geneticseducation.nhs.uk © 2013 NHS National Genetics and Genomics Education Centre How to draw a family history."— Presentation transcript:

1 Genetics and genomics for healthcare © 2013 NHS National Genetics and Genomics Education Centre How to draw a family history pedigree Symbols and relationship lines

2 Genetics and genomics for healthcare © 2013 NHS National Genetics and Genomics Education Centre Taking a genetic family history is important in assisting the diagnosis of a condition in a family. Drawing a family history pedigree The family history is usually recorded as a ‘family tree’ using symbols and lines. These standardised symbols and lines have been adopted internationally. This ensures that health professionals throughout the world can understand and interpret family history information. Each of the symbols represent either an individual or an event in a family. They then need to be connected together to show the relationships in a family. We do this using lines. Drawing lines between pedigree symbols correctly is the sign of a good family history pedigree.

3 Genetics and genomics for healthcare © 2013 NHS National Genetics and Genomics Education Centre Symbols A square represents a male A circle represents a female If an individual is affected by a condition, the symbol is coloured in A diamond is entered if the sex of a family member is unknown 5 A number in a symbol represents multiple individuals

4 Genetics and genomics for healthcare © 2013 NHS National Genetics and Genomics Education Centre Symbols The letter ‘P’ inside a symbol represents a pregnancy Male A miscarriage is represented by a triangle with the sex written underneath. If the sex is unknown then this is left blank. Female If a member of the family is deceased, a line is drawn through the symbol An arrow indicates the person providing the family history information P

5 Genetics and genomics for healthcare © 2013 NHS National Genetics and Genomics Education Centre Lines To indicate a marriage, a horizontal line is drawn between the male and female symbols. To show a divorce or separation, two downward lines are made from top right to bottom left over the marriage line. To indicate a marriage between blood relatives (consanguineous relationship), two marriage lines are drawn horizontally between the male and female symbols. There are four different types of lines used when drawing a pedigree. The first is called a relationship line and is a horizontal line between two people.

6 Genetics and genomics for healthcare © 2013 NHS National Genetics and Genomics Education Centre Lines After the relationship line, a vertical line is drawn from parents to children and is called a ‘line of descent’. Line of descent Sibship line Individual line Relationship line The ‘sibship line’ is a horizontal line joining brothers and sisters. Each person has an ‘individual line’ which is a vertical line drawn down from the sibship line. P

7 Genetics and genomics for healthcare © 2013 NHS National Genetics and Genomics Education Centre To access other resources for teaching and learning genetics, please visit:


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