53 Following Patterns of Inheritance in Humans What is a Pedigree Flowchart Genetic Family Tree Symbols show inheritance patterns of traits over generations Used to determine presenceabsence of an allele responsible for disease in an individual ID: 362479
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Slide1
SBI3U
5.3-
Following
Patterns
of
Inheritance
in
HumansSlide2
What is a Pedigree?
Flowchart; “Genetic Family Tree
Symbols show inheritance patterns of traits over generations
Used to determine presence/absence of an allele responsible for disease in an individual.Slide3
Pedigree
SymbolsSlide4
*NOTE
:
Roman numerals symbolize generations
Birth order, within each group of offspring, is drawn left to right (first born to last born)
EXAMPLE:Slide5
Autosomal Inheritance
Inheritance of traits on chromosomes 1 -
22(autosomes)
Autosomal dominant:
Disease causing allele is dominant
Individual has one or both copies of the allele
Autosomal recessive:
Disease causing allele is recessive
Individual has both copies of alleleSlide6
Autosomal Dominant
Inheritance
Each affected individual has an affected parent; no skipping of generations.
Males and females are equally affected.
About 1/2 of the offspring of an affected individual are affected (the recurrence risk is 1/2).
Normal siblings (ex. II-3) of affected individuals have all normal offspring.Slide7
Example- Pedigree:
Autosomal
Dominant
Inheritance
Question: Why must individual II-1 be heterozygous?Slide8
Autosomal
Recessive Inheritance
Two unaffected parents can have an affected child
This only happens if both the parents are
“
carriers”
Both are
heterozygous
(so they do not express it)Slide9
Example –Pedigree:
Autosomal Recessive Inheritance
Question: Are parents II 3 and 4 heterozygous or homozygous? Explain
.Slide10
Examples of Human
Diseases
–
Autosomal Inheritance
1)Sickle Cell Anemia
2)Huntington
Disease
Recessive
Irregularly shaped red blood cells
Dominant
Loss of muscle control and mental ability
3) Cystic Fibrosis
Recessive
Mucus
build up in lungs = trouble breathingSlide11
Let’s try this…Who
can roll their tongue???
http://www.zerobio.com/drag_gr11/pedigree11_flash.htm
Slide12
Genetic TestsSlide13
Genetic Counselling
Genetic counsellors are trained in human
genetics
Work with families/individuals who may be at risk for a genetic disorder.
Look at probability
of passing on a disease-causing allele to
children through family history using PedigreesSlide14
Class Discussion:
What
issues might be associated with genetic testing?Slide15
Gene Therapy
Technique used by introducing
the correct form of a gene into a patient’s
genome
Goal?
For curing genetic disorders!!
METHOD-
Normal
gene
is copied and inserted
into
vector
(viruses are used
bc
they
can
easily infect human cells. Slide16Slide17
The Future of Gene Therapy…
Still in the experimental stage
2 Problems/ Obstacles:
1)Problems
with type of vector
2)Poor integration of gene
into chromosomes
In 2000, first human gene therapy treatment was performed for heart disease at St. Mike’s Hospital, TorontoSlide18
Homework
Read and review 5.3-pg 219-226
Chapter 5 QUIZ T.B.A
Complete pg. 227 # 2, 7, 8
Pedigree Assignment