Download Blood Type

T. Trimpe 2006 http://sciencespot.net/
Serology
Serology is the examination and analysis of body fluids. A
forensic serologist may analyze a variety of body fluids
including saliva, semen, urine, and blood. From 1950 to the
late 1980s, forensic serology was a most important part of lab
procedures. With the development of DNA techniques, more
time, money, and significance were placed on developing DNA
labs. However, with limited funds and the time required for
DNA testing, most labs still use many of the basic serology
testing procedures.
Historical Perspective of Blood Typing
Around 1900, Karl Landsteiner discovered that there are four
different types of human blood based on the presence or
absence of specific antigens found on the surface of the red
blood cells.
In 1940, Landsteiner and Weiner reported the discovery of the Rh
factor by studying the blood of the Rhesus monkey. 85 percent
of Caucasians, 94 percent of African Americans, and 99
percent of all Asians Americans are Rh positive.
Blood Terminology
ABO blood groups—based on having A, B, both, or no antigens on
red blood cells
Rh factor—may be present on red blood cells; positive if present and
negative if not
Antigen—a substance that can stimulate the body to make antibodies.
Certain antigens (proteins) found in the plasma of the red blood
cell’s membrane account for blood type.
Antibody—a substance that reacts with an antigen
Agglutination—clumping of red blood cells; will result if blood types
with different antigens are mixed
What makes up our blood?

RED BLOOD CELLS (erythrocytes) – The most
abundant cells in our blood; they are produced in the
bone marrow and contain a protein called
hemoglobin that carries oxygen to our cells.
What makes up our blood?

PLATELETS
(thrombocytes) – The
clotting factors that are
carried in the plasma;
they clot together in a
process called
coagulation to seal a
wound and prevent a
loss of blood
What makes up our blood?

PLASMA – The yellowish liquid portion of
blood that contains electrolytes, nutrients
and vitamins, hormones, clotting factors,
and proteins such as antibodies to fight
infection.
What makes up our blood?

White Blood Cells (leukocytes) – they are
part of the immune system and destroy
infectious agents called pathogens
Blood Facts
There
are about one billion
red blood cells in two to three
drops of blood. For every 600
red blood cells, there are
about 40 platelets and one
white cell.
You blood type

These two genes determine your blood type
by causing proteins called
AGGLUTINOGENS to exist on the surface
of all of your red blood cells.
How common are the 4 blood
types?
4%
11%
45%
40%
http://www.lanecountyblood.org/images/other/bloodfacts.jpg
Blood Genetics
The human ABO gene is on
chromosome 9.
 Everyone has two copies of
chromosome 9 so you have two ABO
genes.
 One copy is inherited from our mother,
the other from our father.

Alleles

There are three versions (called
“alleles”) of this blood type gene: A, B,
and O.

A person’s blood type is determined by
which allele he/she inherits from each
parent.
Pheno vs. Geno
The genetic makeup of an organism is
called the “genotype”.
 The “phenotype” is the visible
properties of an organism.
 In this case, the A, B, and O allele
combination a person has is their
genotype
 Their blood type is their phenotype.

Determining the Genotype
The blood type gene has three different
alleles:
 IAIA is Type A
 IAIB is Type AB
 IBIB results in Type B
 ii is Type O
Determining the Genotype

Scenario:
 Mom has the alleles IAIA for blood type and
Dad has the alleles IBIB blood type.
 What will be the blood type for their child?
Practice
Suppose that a mother has blood Type A
and genotype IAi and the father has
blood Type B and genotype IBi. Draw a
Punnett square to show the possible
genotypes of their children.
What are the phenotypes of the kids?
Stats
O+
OA+
AB+
BAB+
AB-
1 in 3 persons
1 in 15 persons
1 in 3 persons
1 in 16 persons
1 in 12 persons
1 in 67 persons
1 in 29 persons
1 in 167 persons
Can Blood Be Individualized?
Is based on the typing of proteins and enzymes.
Blood proteins have subtypes.
 Most people are familiar with at least one
common polymorphism in blood: Hb, which
causes sickle-cell anemia.
 You can also extract DNA from it.

Number of people with a
blood type

3 surface antigens as probability
1. Determine % of people with that surface
antigen
2. Determine the ratio by dividing 100 by the
%
3. Multiple the ratios together
4. Obtain the # of people out of 100 with those
3 antigens
DATA
Type of Blood
% of People
A
41
B
10
AB
4
O
45
Rh +
85
Rh -
15
M
30
N
22
S
48
Determine the likelihood…
1.
Of an individual with Type A, N and Rh –
2.
Of an individual with Type AB, S and Rh +
3.
Of an individual with Type O, M, Rh -
Blood Typing
Blood type A has antigen A on the surface of the
cell and will agglutinate with blood type B.
Blood type B has antigen B on the surface of the
cell and will agglutinate with blood type A.
Blood type AB has antigens A and B on the
surface of the cells and will not agglutinate
with either type A or type B blood.
Blood type O has neither antigen A nor B and
will not agglutinate.
What are blood types?
There are 3 alleles or genes for
blood type: A, B, & O. Since we
have 2 genes, there are 6 possible
combinations.
Blood Types
AA or AO = Type A
BB or BO = Type B
OO = Type O
AB = Type AB
http://learn.genetics.utah.edu/units/basics/blood/types.cfm
Rh Factors
 The
presence of the
protein, or lack of it, is
referred to as the Rh (for
Rhesus) factor.
 If your blood does
contain the protein, your
blood is said to be Rh
positive (Rh+). If your
blood does not contain
the protein, your blood
is said to be Rh
negative (Rh-).
A+
AB+ BAB+ ABO+ O-
A
Blood Typing
A
Rh
Use the results shown to determine the
blood type for each sample.
B
Rh
B
Blood Type: ___
+ = present
A
A
Rh
- = absent
B
A
Rh
B
Blood Type: ___
Blood Type: ___
Rh
B
Blood Type: ___
Blood Type: ___
How can blood be used as
evidence?
spatter – Can be analyzed
to determine PATTERNS that
give investigators clues to how a
crime might have happened.
 Blood
Objectives of Bloodstain
Pattern Analysis

Can provide information about:
 Origin of bloodstain
 Objects that produced bloodstain
 Distance from bloodstain to target
 Position of victim and assailant
 Movement of victim and assailant
 Number of blows/shots
Physical Properties of Blood

Viscosity
 Thickness of a liquid

Surface tension
 Adhesion
○ Attractive forces between unlike molecules
 Cohesion
○ Attractive forces between like molecules
 Capillary action
○ When surface tension causes a liquid to be drawn
up in opposition to gravity
Size of Bloodstain
Shape of Bloodstain
On impact with hard, smooth, nonporous surfaces (tile,
glass)
○ Little to no distortion of stain
○ Surface tension of blood drop resisting rupture
On impact with rough/textured, porous surfaces (concrete)

Disrupts surface tension of blood drop
• Stain will exhibit distortion,
irregular shapes, and spiny edges
– Spines = pointed edges of
bloodstains that radiate away
from the center of the stain
• May also see satellite spatter
Angle of Impact
A spherical drop of blood impacting a
horizontal surface should create a circular
stain
 A drop of blood impacting a nonhorizontal
surface creates a more elongated or
elliptical stain due to the blood “skidding”
across the target surface

 This allows you to make 2 determinations
○ Directionality of stain
○ Angle of impact
Directionality
Parent Stain
with tail pointing
in direction of
travel
Tail of cast off
stain points
back to parent
stain
Angle of Impact

The more acute the angle of impact =
the greater the elongation of the stain
 Length increases and width decreases

By accurately measuring the length and
width of the bloodstain then, the angle of
impact can be calculated using the
following equation:
Angle of Impact = arc sin (width/length)
Angle of Impact
ARC SIN = Width (a) 1.5cm
Length (c) 3.0cm
Points of Convergence
Points of Convergence
Bloodstain Categories

3 Categories
 Passive
○ Only acted on by gravity and friction
 Spatter
○ Subject to some force other than gravity and friction
 Altered
○ Stains whose physical appearance has been changed in
some way
Classification of Spatter Bloodstains
Low-Velocity Impact Spatter
 Less than 5 ft/sec
 Blood spots 4-8 mm in diameter
Medium-Velocity Impact Spatter
– 5-100 ft/sec
– Blood spots 4 mm in diameter or less
High-Velocity Impact Spatter
– Over 100 ft/sec
– Blood spots 1 mm in diameter or less
Altered Bloodstains
Diffusion
Unknown Stain at a Scene
Questions to be answered:
Is it blood?
Is it human blood?
Whose is it?
Determine blood type,
alcohol content, drugs
present
OVERVIEW Presumptive Tests for Blood Determination
Kastle-Meyer color test—a mixture of
phenolphthalein and hydrogen peroxide; the
hemoglobin will cause the formation of a deep
pink color if blood is present
Hematest tablet—reacts with the heme group in
blood, causing a blue-green color
Luminol test—reaction with blood to produce light
The Kastle-Meyer Test
When blood, phenolphthalein and
hydrogen peroxide are mixed, the
hemoglobin in the blood will cause the
normally colorless phenolphthalein to a
bright pink color
 This test can yield some false positives
 Certain vegetable matter can produce
the bright pink positive (such as
potatoes)

Other blood detection tests
Doctors use Hemastix© strips to detect
blood in urine
 But these strips can be used at a crime
scene to detect fresh or dried blood.
 One simply moistens them with distilled
water and wipes the bloodstain
 A color change to green is a positive
indicator of blood

Bayer Hemastix©
Luminol
Luminol is a chemical that exhibits
chemiluminescence, with a striking blue glow,
when mixed with an appropriate oxidizing agent.
It is a white to slightly yellow crystalline solid that
is soluble in water and most polar organic
solvents.
 Usually, a solution of hydrogen peroxide (H2O2)
and a hydroxide in water is used as the activator.
 In the presence of a catalyst such as an iron
compound, the hydrogen peroxide is
decomposed to form oxygen and water:

What do you see with luminol?
It glows a bright blue in the dark, when it comes in contact with bloo
Advantages of using
Luminol
Allows one to detect stains that would
not be ordinarily be visible
 Extremely sensitive - can use it in very
dilute concentrations
 This allows the CSI to spray large areas
with it
 It does not interfere with DNA, so a CSI
can collect samples for DNA analysis
even after it was sprayed with luminol.

Bloody Footprints that were wiped
Luminol glows
even in the
presence of
certain other fluids
– semen, feces,
bleach, tonic
water, etc.
So we know it’s blood – but is it
human?
 The
Precipitin Test
 Rabbits injected with human blood
 They make antibodies in their serum
 They are bled and the serum
recovered
 The serum is called human
antiserum, because it will react to
human antigens
 It will cause coagulation when
Precipitin Test
(Human blood)
(Human antiserum
made in rabbits)
Gel Diffusion Test
Antigen (blood) and antibodies (human
antiserum from rabbits) are placed in
separate wells in a gel.
 They are forced to move towards each
other.
 If they bind to each other, they form a
single line of precipitate in between the
wells
 This is a positive for human blood
