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Pedigree Chart NotesGenetic Family Tree

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What is a Pedigree?

A pedigree is a chart of the genetic history of family over severalgenerations.

Scientists or a genetic counselor can find out aout your family historyma!e this chart to trac! genetic disorders.

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"ocaulary

Autosomal gene# a gene found on any chromosome e$cept for the se$ chromosome

chromosomes numered %#&&.

Se$#lin!ed gene# a gene found on a se$ chromosome '( or )*.

+ominant# ,hen an allele is stronger and mas!s any recessive allele.

-ecessive# an allele that is ,ea!er and not sho,n ,hen paired ,ith a dominant al

Carrier ,hen a recessive gene is present ut does not affect the person ,ho carri

person is called a 0carrier1. They are ale to pass this recessive trait to offspring.

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Pedigree Symols

2ale

Female

Couple 3ffspring'Silings*

+eceased

Affected

'4as +isorder*

5n# Affected

'No +isorder*

Carrier

'No +isorder*

Parents

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6nterpreting a Pedigree Chart

%. +etermine if the pedigree chart sho,s an autosomal or (#lin!ed disease.

6f most of the males in the pedigree are

affected the disorder is (#lin!ed

6f it is a 78978 ratio et,een men and

,omen the disorder is autosomal.

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6nterpreting a Pedigree Chart

&. +etermine ,hether the disorder is dominant or recessive.

6f the disorder is dominant/ one of the

parents must have the disorder.

6f the disorder is recessive/ neither

parent has to have the disorder ecau

they can e hetero:ygous.

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Summary

Pedigrees are family trees that e$plain your genetic history.

Pedigrees are used to find out the proaility of a child having a disorder in a

particular family.

To egin to interpret a pedigree/ determine if the disease or condition is

autosomal or (#lin!ed and dominant or recessive.