PEDIGREE CHARTS - PowerPoint PPT Presentation

About This Presentation
Title:

PEDIGREE CHARTS

Description:

A family history of a genetic condition Pages 1-3 & 6-9 taken from Paul Billiet at the following website: saburchill.com/IBbiology/.../images/05PEDIGREE CHARTS.ppt – PowerPoint PPT presentation

Number of Views:187
Avg rating:3.0/5.0
Slides: 19
Provided by: Billi162
Category:

less

Transcript and Presenter's Notes

Title: PEDIGREE CHARTS


1
PEDIGREE CHARTS
  • A family history of a genetic condition

Pages 1-3 6-9 taken from Paul Billiet at the
following website saburchill.com/IBbiology/.../im
ages/05PEDIGREE CHARTS.ppt
2
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.

3
Studying human genetics
  • You cannot make humans of different types breed
    together
  • Pedigree charts offer an ethical way of studying
    human genetics
  • Today genetic engineering has new tools to offer
    doctors studying genetic diseases
  • A genetic counsellor will still use pedigree
    charts to help determine the distribution of a
    disease in an affected family

4
Sex on a Pedigree
  • Males
  • Females

5
Connecting Lines
  • Marriage horizontal line between two people
  • Siblings horizontal line above boxes
  • Twins
  • Fraternal
  • Identical

Children are listed from youngest to oldest (left
to right)
6
Symbols used in pedigree charts
  • Normal male Affected male
  • Normal female Affected
    female
  • or autosomal carrier
    (heterozygote )
  • x-linked carrier
  • or deceased

7
Organizing the pedigree chart
  • A pedigree chart of a family showing 20
    individuals

8
Organizing the pedigree chart
  • Generations are identified by Roman numerals

9
Organizing 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

10
Reading a Pedigree Chart
  • Autosomal or x-linked trait?
  • If the affected are mostly males then the trait
    is x-linked
  • If the affected is a fairly even ratio between
    males and females then the trait is autosomal

11
Autosomal or X-linked?

12
Autosomal

13
Determining Dominant or Recessive Trait?
  • If the disorder is dominant one of the parents
    must have the disorder
  • If the disorder is recessive then neither of the
    parents HAS to have the trait because they are
    heterozygous. However one of both may have the
    disorder

14
Dominant or recessive?
15
Dominant
16
Dominant or Recessive?
17
Recessive
Some times carriers are not listed as a half
filled in square/circle. You must interpret the
pedigree
18
Pedigrees
  • Remember.
  • you must READ and INTERPRET the pedigree.
Write a Comment
User Comments (0)
About PowerShow.com