A pedigree chart is a diagram that shows the occurrence and appearance or phenotypes of a particular gene or organism and its ancestors from one generation to the next, most commonly humans, show dogs, and racehorses.

An important tool a geneticist uses to trace the inheritance of traits is a pedigree chart, for example, you can use a pedigree chart to track an inherited trait through several generations of a family. It is a family history and details about an earlier generation that may be uncertain as memories fade.

Pedigree chart template

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Elements of Pedigree chart

Pedigrees use a standardized set of symbols

  • Squares represent males
  • Circles represent females.
  • If the sex of the person is unknown a diamond is used. Someone with the phenotype in question is represented by a filled-in (darker) symbol.
  • Heterozygotes, when identifiable, are indicated by a shaded dot inside a symbol or a half-filled symbol.
  • Relationships in a pedigree are shown as a series of lines.
  • Parents are connected by a horizontal line and a vertical line leads to their offspring.
  • The offspring are connected by a horizontal sibship line and listed in birth order from left to right.
  • If the offspring are twins then they will be connected by a triangle. If an offspring dies then its symbol will be crossed by a line.
  • If the offspring is stillborn or aborted it is represented by a small triangle.

Pedigree chart symbols

Pedigree chart examples

Pedigree chart example

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Pedigree chart medical example

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Linked recessive pedigree chart example

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Pedigree probability example

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