Blood bank

• Genetics


  Study of transmission of inherited characteristics
• Branches of genetics


  • Population genetics
  • Cellular genetics
  • Molecular genetics
• Gregor Mendel


  The father of genetics. The one who postulated the law of inheritance
• Meiosis


  Meiosis is the process of cell division unique to gametes (ova and sperm). In contrast to mitosis, the process of meiosis produces four gametes with genetic variability. This results in four unique, rather than two identical, daughter cells.
• Interphases / Non-Mitosis stages

  • G0 (quiescence/resting phase)
  • G1 (gap 1)
  • S phase (DNA synthesis)
  • G2 (gap 2)
• Prophase


  1. The chromatin becomes tightly coiled

  2. Nucleolus and nuclear envelope disintegrate

  3. Centrioles move to opposite poles of the cell
• Mutation


  Any change in the structure or sequence of DNA, whether it is physical or biochemical. An organism is referred to as a mutant if its DNA sequence is different from that of the parent organism
• Transcription


  Transcription is the cellular process by which DNA is copied into RNA. Although mRNA accounts for only a small percent of the total RNA inside a eukaryotic cell, it has the extremely important role of being a "transportable" and disposable form of the genetic code.
• Transcription


  Transcription is an enzymatic process whereby genetic information in a DNA strand is copied into an mRNA complementary strand. Eukaryotic mRNA is modified after it is made by various processing steps, such as the removal of introns and addition of a poly-A tail to the end. These processing steps take place in the nucleus of the cell before the mRNA is exported to the cytoplasmic ribosomes for translation.
• Translation


  Translation is the cellular process by which RNA transcripts are turned into proteins and peptides, the structural and functional molecules of the cell.
• Translation


  1. Translation is a complicated process and involves three major steps: initiation, elongation, and termination.

  2. Translation takes place on the rough endoplasmic reticulum (ER) in the cytoplasm. Also called the rough ER, it is the site of the ribosomes, which are organelles composed of proteins and ribosomal RNA (rRNA).
• The term 'blood group' usually refers to an individual's combination of Red Blood Cell (RBC) surface antigens. Antigens are specific sites on different proteins, glycoproteins or glycolipids that form parts of the RBC membrane which the immune system can interact with. These proteins have numerous functions such as: membrane transporters (Diego, Kidd), receptor and adhesion molecules (Duffy, Lutheran), complement regulatory glycoproteins (Cromer, Knops), enzymes (Yt, Kell, Dombrock), structural components (Diego, Gerbich) or components of the glycocalyx (MNS).
• Antigens are defined by antibodies that occur either 'naturally' due to encountering antigens ubiquitous in the environment or are formed as a result of active immunization to non-self RBC antigens following exposure to human RBCs from another individual. It is the presence and absence due to inherited variation of red cell surface antigens that defines the blood group of an individual.
• Blood group systems are officially defined as systems of one or more antigens governed by a single gene or complex of two or more closely linked homologous genes. Each system is genetically discrete from every other blood group system. In order for a blood group system and its antigens to be recognized the underlying genetic variation must be identified, sequenced and confirmed to affect phenotype.
• The International Society of Blood Transfusion (ISBT) Working Party for Red Cell Immunogenetics and Blood Group Terminology (ISBT WP) maintains an official record of all currently recognized blood group systems. There are currently 44 recognized blood group systems containing 354 red cell antigens (December 2022). The 44 systems are genetically determined by 49 genes.

  
• ABO Blood Group System

  • Most important of all blood group
  • Most common cause of HTR and HDN
  • Associated with immediate and intravascular hemolysis type of HTR
  • Discovered by Karl Landsteiner in 1901
• ABO Forward Typing / Front/ Direct Typing

  • Specimen: Patient RBC
  • Reagent: Uses commercial antisera, Anti –A (Blue color due to trypan or methylene blue), Anti- B (Yellow color due to flavin)
  • Use: Detection of ABO Antigens
• Relationship between forward and reverse typing

  INVERSELY
• ABO Genotypes and Phenotypes

  • A1
  • A2
  • A1B
  • A2B
  • B
  • O
• Grading of agglutination


  • 0 (No agglutinates)
  • W+ (Many tiny agglutinates)
  • 1+ (25% agglutinates)
  • 2+ (50% agglutinates)
  • 3+ (75% agglutinates)
  • 4+ (100% agglutinates)
• Mixed-field agglutination may look like small to large agglutinates with unagglutinated cells. Mixed-field may also appear as a "halo" or "puff of smoke" of unagglutinated RBCs as the RBC button is dislodged from the test tube bottom.
• ABO Mating


  • A x A
  • B x B
  • AB x AB
  • O x O
  • A x B
• Formation of The ABO Blood Group Antigen


  • Inheritance
  • ABO Genes
  • Chromosome #9
  • A and B genes (Dominant)
  • O gene (Amorph /silent Recessive)
• Glycosyltransferase


  • H (L-fucosyltransferase, L-fucose)
  • A (N-acetylgalactosyltransferase, N-acetyl-D-galactosamine)
  • B (D-Galactosyltransferase, D-galactose)
  • AB (N-acetylgalactosyltransferase, D-Galactosyltransferase, N-acetyl-D-Galactosamine, D-galactose)
  • O (--)
• Genes does not actually code for the production of antigens, but rather for the enzymes that synthesize the antigens.
• B


  Possible outcome: Blood type A, B, AB
• O x O


  • Both parents are blood type O
• O (OO)


  Possible outcome: Blood type O
• A x B


  • Parent A - Blood type A, Parent B - Blood type B
• AB


  Possible outcome: A, B, AB, O
• Formation of The ABO Blood Group Antigen


  1. Inheritance

  2. ABO Genes

  3. Chromosome #9

  4. A and B genes

  5. Dominant

  6. O gene

  7. Amorph /silent

  8. Recessive
• GENE


  • GLYCOSYLTRANSFERASE
  • IMMUNODOMINANT SUGAR
  • Antigen
• H


  • L-fucosyltransferase
  • L-fucose
  • H
• A


  • N-acetylgalactosyltransferase
  • N-acetyl-D-galactosamine
  • A
• B


  • D-Galactosyltransferase
  • D-galactose
  • B
• AB


  • N-acetylgalactosyltransferase
  • D-Galactosyltransferase
  • N-acetyl-D-Galactosamine
  • D-galactose
  • AB
• O


  • --
  • --
  • Unchanged
• Genes does not actually code for the production of antigens but rather produce specific glycosyltransferase
• The H antigen is actually the precursor structure on which A and B antigens are made
• The H and Se genes are not part of the ABO system; however, their inheritance does influence A and B antigen expression