Pedigree_lecture.ppt

Human pedigree

1. Pedigree Analysis

2. Pedigree symbols
Female
Male
Gender
unknown
Deceased
3
n
P

3. Stillborn
Spontaneous
abortion/Miscarriage
Termination of pregnancy
elective reasons
Termination of pregnancy
genetic/affected condition
SB

4. Affected individual
Proband
•1st person in family to
come to medical/genetic
attention
Obligate carrier
Infertility

5. Constructing the Pedigree
Relationship or
marriage
Break in
relationship
Consanguineous
relationship

6. Monozygotic
twins
•(Identical)
Dizygotic twins
•(Fraternal)

7. Adoption
into a family
Adoption out
of a family

8. Include below
gender symbol
name, maiden name
if married &
birthdate or age
Generations are
symbolized by
Roman numerals
Should give current
date on pedigree
John Smith
10-1-49
I.
Current date:
08-31-06

9. Other Abbreviations
d.79y
dx.41y
Died at 79 years of
age
Diagnosed at 41 years
of age

10. Siblings are
drawn left to
right in birth
order
I.
II.
III.

11. Rules of Thumb
Always include a key
At least 3 generations
Use birth dates or ages
Sign and date
Include ancestry with oldest generations

12. Causes of
death or health
problems
should be
noted on the
pedigree or
explained by a
key
Key
Hypertension
Breast cancer
52

13. Autosomal Dominant Inheritance
Each affected individual has one affected
parent
Males and females may be affected
Pattern of inheritance is vertical (passed
from generation to generation)

14. Autosomal
Dominant
Inheritance
I.
II.
III.

15. Autosomal Recessive Inhertance
Do not need a parent who is affected; each
parent must be a carrier of the recessive
gene
Males and females may be affected
Pattern of inheritance is horizontal (usually
seen in siblings)
Offspring of parent with the condition are
obligate carriers

16. Autosomal
Recessive
Inheritance
I.
II.
III.

17. X-Linked Inhertance
Gene is located on Xchromosome
Female is usually clinically normal and
disorders are typically seen more often in
males than females
Absence of male-to-male transmission

18. X-Linked
Inheritance
I.
II.
III.