basic knowledge of pedigree, making pedigree, the pattern of inheritance

1. Pedigree Nomenclature
(Pedigree Analysis)
Ikram Ullah
M.Phil MLSc

2. Overview
I. What is a pedigree?
a. Definition
b. Uses
II. Constructing a pedigree
a. Symbols
b. Connecting the symbols
 Interpreting a pedigree

3. What is a Pedigree?
 A pedigree is a chart of the genetic history of family
over several generations.
 Scientists or a genetic counselor would find out about
your family history and make this chart to analyze.
 The term pedigree arose in the fifteenth century, from the
French pie de grue, which means “crane’s foot.”

4.  Charts called pedigrees display family
relationships and depict which relatives have
specific phenotypes and, sometimes, genotypes
A pedigree in genetics differs from a family tree in
genealogy
And from a genogram in social work, in that it
indicates disorders or traits as well as relationships
and ancestry

5.  Pedigree: In a pedigree chart, only the direct ancestors of
the person of interest are listed.
 In other words, my pedigree sheet would include my mother
and her parents.
 But it would not include my mother's siblings or her parents'
siblings.
 This is because those people are not my direct ancestors
 Family Tree: a family tree would show all of those people
who are omitted from the pedigree chart.
 It would show my aunts and uncles and cousins and my
great aunts and uncles as well.
 A family tree, therefore, gives much more information than a
pedigree sheet does

6.  Genogram
 A genogram is a tool for tracking family history and
relationships similar to a family tree.
 Genograms indicate gender, age, ethic origin, health status,
educational achievements, family relationships, social
relationships, and emotional relationships using a series of
color coded lines, shapes, and symbols.

9. Constructing a Pedigree
 Female
 Male

10. Connecting Pedigree Symbols
Examples of connected symbols:
 Fraternal twins
 Identical twins

11. Connecting Pedigree Symbols
Examples of connected symbols:
 Married Couple
 Siblings

12. Example
 What does a pedigree chart look like?

13. Symbols in a Pedigree Chart
 Affected
 X-linked
 Autosomal carrier
 Deceased

14. Interpreting a Pedigree Chart
1. Determine if the pedigree chart shows an
autosomal or X-linked disease.
– If most of the males in the pedigree are
affected the disorder is X-linked
– If it is a 50/50 ratio between men and
women the disorder is autosomal.

15. Example of Pedigree Charts
 Is it Autosomal or X-linked?

16. Answer
 Autosomal

17. Interpreting a Pedigree Chart
1. Determine whether the disorder is
dominant or recessive.
– If the disorder is dominant, one of the
parents must have the disorder.
– If the disorder is recessive, neither
parent has to have the disorder because
they can be heterozygous.

18. Example of Pedigree Charts
 Dominant or Recessive?

19. Answer
 Dominant

20. Example of Pedigree Charts
 Dominant or Recessive?

21. Answer
 Recessive

22. Summary
 Pedigrees are family trees that explain your
genetic history.
 Pedigrees are used to find out the
probability of a child having a disorder in a
particular family.
 To begin to interpret a pedigree, determine
if the disease or condition is autosomal or X-
linked and dominant or recessive.