Transcript pedigree charts - Montgomery County Schools

PEDIGREE
CHARTS
A family history of a genetic condition
© 2007 Paul Billiet ODWS
What is a pedigree chart?
Pedigree charts show a record of the family
of an individual
 They can be used to study the transmission
of a hereditary condition
 They are particularly useful when there are
large families and a good family record over
several generations.

© 2007 Paul Billiet ODWS
Symbols used in pedigree
charts





Normal male
Affected male
Normal female
Affected female
Marriage
A marriage with five children, two
daughters and three sons. The eldest
son is affected by the condition.
Eldest child  Youngest child
© 2007 Paul Billiet ODWS
Organising the pedigree
chart

A pedigree chart of a family showing 20
individuals
© 2007 Paul Billiet ODWS
Organising the pedigree
chart

Generations are identified by Roman
numerals
I
II
III
IV
© 2007 Paul Billiet ODWS
Organising the pedigree
chart


Individuals in each generation are identified by Arabic
numerals numbered from the left
Therefore the affected individuals are II3, IV2 and IV3
I
II
III
IV
© 2007 Paul Billiet ODWS
Interpreting a Pedigree

What can you tell from a pedigree?

Whether a family has an autosomal or sexlinked disease or disorder
• Autosomal disorder: appears in both sexes
equally
• Sex-linked disorder: allele is located only on the
X or Y chromosome. Most sex-linked genes are
on the X chromosome and are recessive
• So who would have an X-linked disorder more often,
boys or girls?

Whether a disorder is dominant or recessive
Is this disorder 1) autosomal or sex
linked, 2) dominant or recessive?
Grandparents
Grandparents
Parents
Aunts, Uncles
Aunts, Uncles
Brother
You
Sex Linked! (in this case
allele is recessive and
located on the X
chromosome)
Is this disorder 1) autosomal or sex
linked, 2) dominant or recessive?
Grandparents
Grandparents
Parents
Aunts, Uncles
Aunts, Uncles
Autosomal dominant!
Brother
You
Is this disorder 1) autosomal or sex
linked, 2) dominant or recessive?
Grandparents
Grandparents
Parents
Aunts, Uncles
Aunts, Uncles
Autosomal recessive!
Brother
You
Common Genetic Disorders
Color blindness
 Sickle cell anemia
 Cystic Fibrosis
 Hemophilia
 Huntington’s Disease

For more info, go to: http://www.ncbi.nlm.nih.gov/pubmedhealth/
Color Blindness
 Deficiency to
percieve colors
 Problem with color-
sensing pigments in
certain nerve cells
of the eye
 About 1 in 10 men
have some form of
color blindness.
 Sex-linked disorder
What are blood types?
There are 3 alleles or genes for blood type: A, B, & O. Since we
have 2 genes, there are 6 possible blood type combinations.
How common is your blood type?
46.1%
38.8%
11.1%
3.9%
Antibodies
Blood Transfusions
A blood transfusion is a procedure in which blood is given to a patient through an
intravenous (IV) line in one of the blood vessels. Blood transfusions are done to replace
blood lost during surgery or a serious injury. A transfusion also may be done if a person’s
body can't make blood properly because of an illness.
Who can give you blood?
Universal Donor
People with TYPE O blood are called
Universal Donors, because they can give
blood to any blood type.
People with TYPE AB blood are called
Universal Recipients, because they can
receive any blood type.
Rh +  Can receive + or Rh -  Can only receive Universal Recipient
Rh Factors
• Scientists sometimes study Rhesus monkeys
to learn more about the human anatomy
because there are certain similarities between
the two species. While studying Rhesus
monkeys, a certain blood protein was
discovered. This protein is also present in the
blood of some people. Other people, however,
do not have the protein.
• The presence of the protein, or lack of it, is
referred to as the Rh (for Rhesus) factor.
• If your blood does contain the protein, your
blood is said to be Rh positive (Rh+). If your
blood does not contain the protein, your blood
is said to be Rh negative (Rh-).
http://www.fi.edu/biosci/blood/rh.html
A+ AB+ BAB+ ABO+ O-