Download Evolution of blood types

3/13/13 Evolution of blood
types
Pearl, Bindu, Lisa, Morgan
Overview
ò  Introduction to ABO blood systems
ò  Pattern- 2 hypotheses
ò  Trans-species polymorphism vs. Convergent evolution
ò  Process- adaptive response in different areas due to
diseases
ò  Clinical significance
ò  Discussion Questions
1 3/13/13 ABO Blood Systems
v Common Beliefs:
Ø  Only humans have the ABO blood system
Ø  Since blood type O is most common in human
beings it is the very first blood type (ancestral
trait)
ABO Blood Systems
ò  ABO blood types were discovered in the 1900’s by Karl Landsteiner
ò 
There are 4 principal types: A, B, O and AB
ò  Blood types are inherited from parents
ò  There are two antigens and two antibodies that are responsible for
the blood type
ò  Antigen: a substance when introduced in to the immune system
stimulates the production of antibodies
ò  Ex: Bacteria, Viruses etc
ò  Antibodies: A Y-shaped protein that is produced by the immune
system when it detects a harmful antigen in the body
2 3/13/13 Determining different blood
types
The Rh Factor
ò  Rh factor – Rhesus Factor
ò  This factor determines if the blood type is positive or negative
ò  If the Rh factor is present on the red blood cells then you have a Rh
positive (+ blood type)
ò  If there is no Rh factor present on the red blood cells then you are
Rh negative (- blood type)
ò  If the Rh factor is positive for both parents then the child will be Rh
positive
ò  While blood types are 100% genetically inherited, the environment
potentially can determine which blood types in a population will be
passed on more frequently to the next generation
3 3/13/13 Inheritance of blood types
ò  Where did it all start?
Ø  2 hypotheses
q  Convergent evolution
q  Polymorphism
2 hypotheses
ò  Convergent – similarity between species caused by a
similar, but evolutionary independent, response to a
common environmental problem
ò  Polymorphism – the existence within a population of
more than one variant for a phenotypic trait, or of more
than one allele.
ò  Coalescence Analysis – attempts to trace all alleles of a
gene shared by all members of a population back to a
most recent common ancestor.
4 3/13/13 Phylogenetic Trees
5 3/13/13 Evolution of blood types due
to diseases
Figure 1. P. falciparum parasite invasion of A, B and O erythrocytes.
Wolofsky KT, Ayi K, Branch DR, Hult AK, et al. (2012) ABO Blood Groups Influence Macrophage-mediated Phagocytosis of
Plasmodium falciparum-infected Erythrocytes. PLoS Pathog 8(10): e1002942. doi:10.1371/journal.ppat.1002942
http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1002942
Evolution of blood types due
to diseases
Figure 2. Infected O erythrocytes are phagocytosed more avidly by
human macrophages.
Wolofsky KT, Ayi K, Branch DR, Hult AK, et al. (2012) ABO Blood Groups
Influence Macrophage-mediated Phagocytosis of Plasmodium falciparuminfected Erythrocytes. PLoS Pathog 8(10): e1002942. doi:10.1371/
journal.ppat.1002942
http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.
1002942
6 3/13/13 Distribution of blood types
across the world
Distribution of blood types
across the world
7 3/13/13 Distribution of blood types
across the world
The Evolutionary Trade-offs
v 
Type A:
§ 
Most likely to survive plague
§ 
Higher rate of heart disease
§ 
Higher risk of contracting smallpox
§ 
v 
v 
Higher risk of developing cancer of the
esophagus, pancreas and stomach
Type B:
§ 
Weaker protection against plague
§ 
Higher risk of pancreatic cancer
§ 
Higher risk of gastrointestinal cancer
ò 
Type O:
§ 
Protective against cardiovascular
problems
§ 
Boosts resistance against tuberculosis
§ 
Increase risk of venous
thromboembolism
§ 
Less likely to get pancreatic cancer
Overall type A seemed to have an increase
probability of getting cancer, and those with
type O have a lower risk.
8 3/13/13 Clinical Significance
ò  Why cant we donate blood to a person that doesn’t have the
same blood type as us?
Ø  Say you have type A blood, and have type B blood injected in to
your body. The antigens in your blood will react with the anti B
of blood type B and the result is agglutinated blood (clumping
of red blood cells) leading to destruction of the donor’s cells and
if severe enough this reaction could cause death.
ò  Why is blood type O considered as an universal donor?
Ø  O- is the universal donor, because it does not contain A, B or Rh
antigens and therefore will not react with anyone.
Discussion Questions
1.  How can we use red queen hypothesis in explaining the
correlation between the diseases and the different blood types?
2.  Based on the percentage of AB and O blood type, one being
the most rare and one being the most common. Can we
suggest that they are being selected for and against? Why
would they be selected for or against when there is tradeoff in
all blood types?
3.  When parents with two different blood types mate then most
of the time the offspring turns out to be fine, but why is it
dangerous to mix two different blood types?
9