Forensic Biology by Richard Li Chapter 10: Blood Group Typing and Protein Profiling Forensic Biology by Richard Li

Blood Groups Antigen polymorphisms that are present on the erythrocyte surface 29 blood group systems E.g. Rh, MNSs, Kell, ABO ABO system is the most commonly used in forensics Forensic Biology by Richard Li

Blood Groups ABO System A, B, AB, O Type A: have A antigen Type B: have B antigen Type AB: both A and B antigens Type O: neither A nor B antigens Found in many tissues other than blood Forensic Biology by Richard Li

Biosynthesis of Antigens O Antigen (H antigen): generated by all Fucosyltransferase Galactosyltransferase Forensic Biology by Richard Li

Secretors vs. Nonsecretors A, B, O antigens are widely distributed in other tissues Approx. 75% of Caucasians Nonsecretors Homozygous for a nonsense mutation in FUT2 resulting in a truncated protein Approx. 20% of Caucasians Forensic Biology by Richard Li

Forensic Applications Individuals divided into four groups Probability of two randomly chosen individuals will be identical for a known blood type is high Can exclude suspects Forensic Biology by Richard Li

Techniques for Blood Group Typing Agglutination Assays Lattes Crust Assay Absorption-Elution Assay Forensic Biology by Richard Li

Forensic Protein Profiling Developed due to limitations with blood group typing Inherited protein polymorphic markers 20-30% of proteins in humans are polymorphic Identification: Electrophoretic separation based on molecular weight and the charge of the protein variants Forensic Biology by Richard Li

Hemoglobin More than 200 Hb variants identified Useful markers Fetal Hb E.g. Infanticide Hemoglobin S Investigative leads for indication of ethnic origin Forensic Biology by Richard Li