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Forensic Biology by Richard Li

Chapter 10: Blood Group Typing (Sec 10.1.1-10.1.3 only). Forensic Biology by Richard Li. Blood Groups. Defined as antigen polymorphisms that are present on the erythrocyte (red blood cell) surface 29 blood group systems E.g. Rh, MNS, Kell, Duffy, Kidd, ABO

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Forensic Biology by Richard Li

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  1. Chapter 10: Blood Group Typing (Sec 10.1.1-10.1.3 only) Forensic Biologyby Richard Li

  2. Blood Groups • Defined as antigen polymorphisms that are present on the erythrocyte (red blood cell) surface • 29 blood group systems • E.g. Rh, MNS, Kell, Duffy, Kidd, ABO • ABO system is the most commonly used in forensics • Used far less now than it used to be • Discovered by Karl Landsteiner in early 1900s

  3. 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 • Can be found in many tissues other than blood • Saliva, semen are most important for forensics

  4. Biosynthesis of Antigens • H antigen: generated by all (or almost all...) • Fucosyltransferase • Encoded by human FUT1 and FUT 2 loci, 19q13.33 • Adds fucose to the end of a glycolipid (FUT1, erythrocytes) or glycoprotein (FUT2, other tissues) • AB antigens: generated by some • Galactosyltransferase (adds to H antigen) • Encoded by the human ABO locus, 9q34.2 • O allele = null (non-functional) • A allele = A-transferase (adds N-acetylgalactosamine) • B allele = B-transferase (adds galactose)

  5. Secretors vs. Nonsecretors • Secretors • Secretion under control of FUT2 gene • If FUT2 functional, H antigen is distributed on surface of cells of tissues other than blood and ABO antigens can be added on in these tissues • Approx. 80% of Caucasians • Non-secretors • Homozygous for a nonsense mutation in FUT2 resulting in a truncated protein • Approx. 20% of Caucasians

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