Forensic Biotechnology Blood typing for distribution T A

Forensic Biotechnology Blood typing for distribution T. A. Roba Attar

Forensic Serology – term used to describe a broad range of laboratory tests using reactions of blood serum and body fluid The serology section of a forensic laboratory may deal with any or all of the following: • blood typing • characterization of unknown blood • stain patterns for crime reconstruction • paternity testing • semen identification in rape cases

Blood basic What makes up our blood? The word blood refers to a highly complex mixture of cells, enzymes, proteins, and inorganic substances. 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. WHITE BLOOD CELLS (Leukocytes) – They are part of the immune system and destroy infectious agents called pathogens.

PLASMA – This is the yellowish liquid portion of blood that contains electrolytes, nutrients and vitamins, hormones, clotting factors, and proteins such as antibodies to fight infection 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. ANTIGENES, usually proteins, are located on the surface of red blood cells and are responsible for blood-type characteristics

Genetics of Blood Types Your blood type is established before you are BORN, by specific GENES inherited from your parents. You inherit one gene from your MOTHER and one from your FATHER. These genes determine your blood type by causing proteins called AGGLUTINOGENS to exist on the surface of all of your red blood cells.

Blood group A blood type (also called a blood group) is a classification of blood based on the presence or absence of inherited antigenic substances on the surface of red blood cells Antigens are glycolipids that the body's immune system recognizes and either mounts an immune response to (by producing antibodies), if the antigen is from a foreign source, or ignores, if the antigen is part of the body itself

Blood group These antigens stick out from red cell membrane These antigens may be proteins, carbohydrates, glycoproteins, or glycolipids, depending on the blood group system There are many antigen sites per red blood cell These antigens are also expressed on tissues other than red cells

ABO blood group Discovered by the Austrian-born American scientist Karl Landsteiner, who found three different blood types in 1900 He was awarded the Nobel Prize in Physiology or Medicine in 1930 for his work Landsteiner described A, B, and O Alfred von Decastello and Adriano Sturli discovered the fourth type, AB, in 1902

ABO Blood group inheritance A total of 32 human blood group system are now recognized by the International Society of Blood Transfusion (ISBT), but the A-B-O and Rh systems are the most important. Blood types are inherited and represent contributions from both parents The ABO blood type is controlled by a single gene (the ABO gene) with three alleles: i, IA, and IB The gene is located on the long arm of the ninth chromosome The IA allele gives type A, IB gives type B, and i gives type O both IA and IB are dominant over i

ABO Blood group inheritance

How common is your blood type?

ABO Blood group Type A individuals do not mount an immune response against A antigens. If they did, the immune system would produce antibodies that would bind to the A antigens and cause the blood to thicken and clump Individuals who are type B don't produce antibodies against B antigens, but they do produce antibodies against A antigens

ABO Blood group Individuals who are type O have neither A antigens or B antigens, so they have antibodies to both types Individuals who are type AB, have both antigens and do not have antibodies to either A or B

ABO Blood group There are no O antigens. Type O individuals simply do not produce any antigens in this blood type group

Rh Factors Scientists sometimes study Rhesus monkeys to learn more about the human anatomy because there are certain similarities between the two species. While studying Rhesus monkeys, a certain blood protein was discovered. This protein is also present in the blood of some people. Other people, however, do not have the protein. The presence of the protein, or lack of it, is referred to as the Rh (for Rhesus) factor.

Rh Blood group It is clinically the most important blood group system after ABO Discovered in 1937 by Karl Landsteiner and Alexander Wiener The Rh blood group system currently consists of 50 defined blood-group antigens D antigen is the most important one

Rh Blood group An individual either has, or does not have, the "Rhesus factor" on the surface of their red blood cells RH gene located on short arm of chromosome 1 The commonly-used terms Rh factor, Rh positive and Rh negative refer to the D antigen only The status is usually indicated by Rh positive (Rh+, does have the D antigen) or Rh negative (Rh-, does not have the D antigen)

Rh Blood group inheritance The Rh factor genetic information is also inherited from our parents, but it is inherited independently of the ABO blood type alleles There are 2 different alleles for the Rh factor known as Rh+ and Rh. Rh factor Rh+ Rh- Possible genotypes Rh+/Rh+ Rh+/Rh. Rh-/Rh-

Red blood cell compatibility Recipient Donor O− O+ A− A+ B− B+ AB− AB+ O− Y N N N N O+ Y Y N N N A− Y N N N A+ Y Y N N B− Y N N N B+ Y Y N N AB− Y N Y N AB+ Y Y Y Y

Forensic of blood Three questions that must be answers by forensic investigator: 1) Is it blood? Kastle-Meyer Test (Phenolphthalein Test) Luminol Test Alternative Light Sources The determination of blood is best made by means of a preliminary color test.

Forensic of blood Tests A positive result from the Kastle-Meyer color test is highly indicative of blood. Hemoglobin causes a deep pink color.

Forensic of blood Tests Alternatively, the luminol test is used to search out trace amounts of blood located at crime scenes. Produces light (luminescence) in a darkened area.

Forensic of blood 2) Is it human blood? Precipitin Test This involves forming antibodies to human blood in an animal. The animal serum thus treated will cause a precipitate to form when reacted with human blood.

Forensic of blood 3) Can it be associated with an individual? blood typing

Forensic of blood Wet blood has more value than dried blood because more tests can be run. For example, alcohol and drug content can be determined from wet blood only. Blood begins to dry after 3 -5 minutes of exposure to air. As it dries, it changes color towards brown and black.

Forensic of blood Blood at the crime scene can be in the form of pools, drops, smears, or crusts. A blood smear on the wall or floor tells the direction of force of the blow. Blood crusts need to be tested with crystalline methods to make sure it's blood.

Blood Evidence Blood samples – Can be analyzed to determine blood type and DNA, which can be matched to possible suspects. Blood droplets – Can be analyzed to give clues to the location of a crime, movement of a victim, and type of weapon. Blood spatter – Can be analyzed to determine patterns that give investigators clues to how a crime might have happened.

Blood typing and forensics Blood typing can be used as an initial test to exclude some suspected sources of a bloodstain Blood typing is performed by mixing a small sample of blood with anti-A or anti-B antibodies (called antiserum) The presence or absence of clumping is determined for each type of antiserum used

Blood typing and forensics If clumping occurs with only anti-A serum, then the blood type is A If clumping occurs only with anti-B serum, then the blood type is B Clumping with both antiserums indicates that the blood type is AB No clumping with either serum indicates that you have blood type O

Blood typing and forensics The Rh positive and Rh negative blood factors can be determined in a similar way Rh factor is determined by mixing anti-Rh (anti-D) serum with the blood If clumping occurs the blood is Rh positive. If no clumping occurs the blood is Rh negative

Blood typing experiment Procedure Sterilize a finger with alcohol swab Use the needle device to extract some blood Place three drops of blood on a slide Label each drop using a marker (anti-A, anti-B, anti. D) Add a drop of anti-A antibodies to blood drop A Add a drop of anti-B antibodies to blood drop B Add a drop of Rh serum to blood drop D Use different toothpicks to stir each sample of serum

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