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Blood groups and Rhesus factor

Blood groups and Rhesus factor. Introduction. Before the 1900s, it was thought that all blood was the same a misunderstanding that led to frequently fatal transfusions of animal blood into humans and hazardous transfusions of blood between people.

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Blood groups and Rhesus factor

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  1. Blood groups and Rhesus factor www.freelivedoctor.com

  2. Introduction • Before the 1900s, it was thought that all blood was the same • a misunderstanding that led to frequently fatal transfusions of animal blood into humans and hazardous transfusions of blood between people. • Cells of body's tissues /organs covered with surface markers, or antigens. RBCs no different • Thus Human blood is not the same—people belong to different blood groups, depending upon the surface markers found on the red blood cell. www.freelivedoctor.com

  3. Introduction • Presently about 22 different grouping systems • functions of many of the blood group antigens not known, and if missing from RBC membrane, there is no ill effect • suggests that if the blood group antigens used to have a function, e.g., one particular blood group antigen made RBcs more resistant to invasion from a parasite, it is no longer relevant today • But the presence or absence of red blood cell antigens becomes extremely important when blood from different people mixes www.freelivedoctor.com

  4. Blood group antigens • are either sugars or proteins, and they are attached to various components in RBC membrane. • E.g, antigens of ABO blood group are sugars, produced by a series of reactions in which enzymes catalyze the transfer of sugar units • DNA determines t type of enzymes they have, thus the type of sugar antigens that end up on their RBCs • In contrast, antigens of Rh blood group are proteins. • DNA holds the info for producing the protein antigens. • The RhD gene encodes the D antigen, a large protein on RBC membrane. Some have a version of gene that does not produce D antigen, and therefore the RhD protein is absent from their RBCs

  5. Chromosomes • Chromosomes are made up of DNA • Make up genes • Code for proteins www.freelivedoctor.com

  6. Glossary • Heterozygous • 2 identical chromosomes with DIFFERENT Gene types i.e. Dominant & Recessive • Homozygous • 2 identical chromosomes with the SAME genes on each chromosome ie Dominant & Dominant www.freelivedoctor.com

  7. Glossary • Locus • Location of a gene on a chromosome • Allele • Variation of a gene that produces an alternative Phenotype • Phenotype • The result of expressing a gene ie Hair colour • Gene • A section of DNA made of bases that code for a phenotype. ie eye colour www.freelivedoctor.com

  8. Glossary • Sex Linked Chromosome • Is either X or Y. Determines gender. Females have XX, males have XY • Autosomal Chromosome • Pairs of chromosomes that have identical gene location, and are the same in Male and Females. Only the code within the gene varies. www.freelivedoctor.com

  9. Glossary • Dominant Gene • A strong gene that only needs one copy on one chromosome to be expressed. • Recessive gene • Weak gene that needs a copy on each autosomal chromosome (M&F), or on each XX in women, or on the X in men, to be expressed www.freelivedoctor.com

  10. The Blood Group Systems   Inheritance and Genetics

  11. History of Blood Groups and Blood Transfusions • Experiments with blood transfusions have been carried out for hundreds of years. Many patients have died and it was not until 1901, when the Austrian Karl Landsteiner discovered human blood groups, that blood transfusions became safer. • He found that mixing blood from two individuals can lead to blood clumping. The clumped RBCs can crack and cause toxic reactions. This can be fatal.

  12. History of Blood Groups and Blood Transfusions (Cont.) • Karl Landsteiner discovered that blood clumping was an immunological reaction which occurs when the receiver of a blood transfusion has antibodies against the donor blood cells. • Karl Landsteiner's work made it possible to determine blood types and thus paved the way for blood transfusions to be carried out safely. For this discovery he was awarded the Nobel Prize in Medicine in 1930. www.freelivedoctor.com

  13. Experiments with blood transfusions, the transfer of blood or blood components into a person's blood stream, have been carried out for hundreds of years. Many patients have died and it was not until 1901, when the Austrian Karl Landsteiner discovered human blood groups, that blood transfusions became safer. Mixing blood from two individuals can lead to blood clumping or agglutination. The clumped red cells can crack and cause toxic reactions. This can have fatal consequences. Karl Landsteiner discovered that blood clumping was an immunological reaction which occurs when the receiver of a blood transfusion has antibodies against the donor blood cells.Karl Landsteiner's work made it possible to determine blood types and thus paved the way for blood transfusions to be carried out safely. For this discovery he was awarded the Nobel Prize in Physiology or Medicine in 1930. Blood Groups, Blood Typing and Blood Transfusions The discovery of blood groups Blood group 0If you belong to the blood group 0 (null), you have neither A or B antigens on the surface of your red blood cells but you have both A and B antibodies in your blood plasma. What are the different blood groups? • The differences in human blood are due to the presence or absence of certain protein molecules called antigens and antibodies. • The antigens are located on the surface of the RBCs and the antibodies are in the blood plasma. • Individuals have different types and combinations of these molecules.   • The blood group you belong to depends on what you have inherited from your parents. www.freelivedoctor.com

  14. What are the different blood groups? • There are more than 20 genetically determined blood group systems known today • The AB0 and Rhesus (Rh) systems are the most important ones used for blood transfusions. • Not all blood groups are compatible with each other. Mixing incompatible blood groups leads to blood clumping or agglutination, which is dangerous for individuals. www.freelivedoctor.com

  15. ABO blood grouping system According to the ABO blood typing system there are four different kinds of blood types: A, B, AB or O (null). www.freelivedoctor.com

  16. In Caucasians the most frequent ABO phenotype is the O followed by A, B and least is AB. Three genes on Chromosome 9 determine the ABO phenotype namely A, B and O gene.

  17. The A and B genes do not code for A or B antigens, but they code for specific enzymes “Glycosyl transferases” which add sugars to a basic precursor substance. • The expression of the A and B antigens requires the presence of an independently inherited H gene.

  18. Enzymes are: • A antigen : α-3-N-acetylgalactosaminyl transferase. • B Antigen :α-3-D-galactosyl transferase • H antigen : α-2-L-fucosyl transferase.

  19. The immunodominant sugar added to produce the • A antigen is : N-acetylgalactoseamine • B antigen is : D-galactose • H antigen is : L-Fucose.

  20. Blood group AIf you belong to the blood group A, you have A antigens on the surface of your RBCs and B antibodies in your blood plasma. Blood group BIf you belong to the blood group B, you have B antigens on the surface of your RBCs and A antibodies in your blood plasma. AB0 blood grouping system www.freelivedoctor.com

  21. Blood Groups, Blood Typing and Blood Transfusions Blood group O If you belong to the blood group O (null), you have neither A or B antigens on the surface of your RBCs but you have both A and B antibodies in your blood plasma. The discovery of blood groups Experiments with blood transfusions, the transfer of blood or blood components into a person's blood stream, have been carried out for hundreds of years. Many patients have died and it was not until 1901, when the Austrian Karl Landsteiner discovered human blood groups, that blood transfusions became safer. Mixing blood from two individuals can lead to blood clumping or agglutination. The clumped red cells can crack and cause toxic reactions. This can have fatal consequences. Karl Landsteiner discovered that blood clumping was an immunological reaction which occurs when the receiver of a blood transfusion has antibodies against the donor blood cells.Karl Landsteiner's work made it possible to determine blood types and thus paved the way for blood transfusions to be carried out safely. For this discovery he was awarded the Nobel Prize in Physiology or Medicine in 1930. What is blood made up of? An adult human has about 4–6 liters of blood circulating in the body. Among other things, blood transports oxygen to various parts of the body. Blood consists of several types of cells floating around in a fluid called plasma.The red blood cells contain hemoglobin, a protein that binds oxygen. Red blood cells transport oxygen to, and remove carbon dioxide from, the body tissues.The white blood cells fight infection.The platelets help the blood to clot, if you get a wound for example.The plasma contains salts and various kinds of proteins. What are the different blood groups? The differences in human blood are due to the presence or absence of certain protein molecules called antigens and antibodies. The antigens are located on the surface of the red blood cells and the antibodies are in the blood plasma. Individuals have different types and combinations of these molecules. The blood group you belong to depends on what you have inherited from your parents. There are more than 20 genetically determined blood group systems known today, but the AB0 and Rh systems are the most important ones used for blood transfusions. Not all blood groups are compatible with each other. Mixing incompatible blood groups leads to blood clumping or agglutination, which is dangerous or individuals. Nobel Laureate Karl Landsteiner was involved in the discovery of both the AB0 and Rh blood groups. AB0 blood grouping system Blood group AB If you belong to the blood group AB, you have both A and B antigens on the surface of your RBCs and no A or B antibodies at all in your blood plasma. www.freelivedoctor.com

  22. Why do individuals produce antibodies to antigens they do not have? • The "A“ and "B" antigens are also produced by some other plants and microorganisms. Thus, individuals who do not recognize one or more of these antigens as "self" will produce antibodies against the plant or microbial antigens. • These antibodies will also react with human antigens of the same kind whether introduced via a blood transfusion or a tissue graft. www.freelivedoctor.com

  23. ABO inheritance and genetics • The ABO gene is autosomal (the gene is not on either sex chromosomes) • The ABO gene locusis located on the chromosome 9. • A and B blood groups are dominant over the O blood group • A and B group genesareco-dominant • Each person has two copies of genes coding for their ABO blood group (one maternal and one paternal in origin) www.freelivedoctor.com

  24. AUTOSOMAL CHROMOSOME The alleles for Blood group are in the same place on the chromosome 9. However the genes have a different code giving the different blood group A B Nnamdi Nzea one alleles from Nnamdi and one from Nzea www.freelivedoctor.com

  25. What do co-dominant genes mean? This meant that if a person inherited one A group gene and one B group gene their red cells would possess both the A and B blood group antigens. These alleles were termed A ( which produced the A antigen ), B (which produced the B antigen) and O (which was "non functional"and produced no A or B antigen) www.freelivedoctor.com

  26. Possible Blood group Genotypes www.freelivedoctor.com

  27. Possible Blood group Genotypes www.freelivedoctor.com

  28. Blood Group Antigens on RBCs Antibodies in Serum Genotypes A A Anti-B AA or AO B B Anti-A BB or BO AB A and B Neither AB O Neither Anti-A and anti-B OO • The ABO blood groups • The most important in assuring a safe blood transfusion. • The table shows the four ABO phenotypes ("blood groups") present in the human population and the genotypes that give rise to them. www.freelivedoctor.com

  29. Why group A blood must never be given to a group B person? • Giving someone blood from the wrong ABO group could be fatal. • The anti-A antibodies in group B attack group A cells and vice versa. • Blood group O negative is a different story.

  30. The Rhesus (Rh) System complicated here, because there's another antigen to be considered - the Rh antigen.Some of us have it, some of us don't. If it is present, the blood is RhD positive, if not it's RhD negative. So, for example, some people in group A will have it, and will therefore be classed as A+ (or A positive). While the ones that don't, are A- (or A negative). And so it goes for groups B, AB and O. www.freelivedoctor.com

  31. The Rhesus (Rh) System (Cont.) • Rh antigens are transmembrane proteins with loops exposed at the surface of red blood cells. • They appear to be used for the transport of carbon dioxide and/or ammonia across the plasma membrane. • They are named for the rhesus monkey in which they were first discovered. • RBCs that are "Rh positive" express the antigen designated D. • 85% of the population is RhD positive, the other 15% of the population is running around with RhD negative blood. www.freelivedoctor.com

  32. BloodType A person with Rh- blood does not have Rh antibodies naturally in the blood plasma Genotype AllelesProduced Rh positive RR R Rr R or r Rh negative rr r Rh Blood Group and Rh Incompatibility www.freelivedoctor.com

  33. Do you know which blood group you belong to? According to above blood grouping systems, you can belong to either of following 8 blood groups: www.freelivedoctor.com

  34. A person with Rh- blood can develop Rh antibodies in the blood plasma if he or she receives blood from a person with Rh+ blood, whose Rh antigens can trigger the production of Rh antibodies. • A person with Rh+ blood can receive blood from a person with Rh- blood without any problems. www.freelivedoctor.com

  35. Why is an Rh incompatibility so dangerous when ABO incompatibility is not during pregnancy? • Most anti-A or anti-B antibodies are of the IgM class (large molecules) and these do not cross the placenta. • In fact, an Rh−/type O mother carrying an Rh+/type A, B, or AB foetus is resistant to sensitisation to the Rh antigen. • Her anti-A and anti-B antibodies destroy any foetal cells that enter her blood before they can elicit anti-Rh antibodies in her. www.freelivedoctor.com

  36. Rh incompatibility during pregnancy (cont.) • This phenomenon has led to an effective preventive measure to avoid Rh sensitisation. • Shortly after each birth of an Rh+ baby, the mother is given an injection of anti-Rh antibodies (or Rhogam). • These passively acquired antibodies destroy any foetal cells that got into her circulation before they can elicit an active immune response in her. www.freelivedoctor.com

  37. The ABO Blood Group System Laboratory  Determination of the ABO System www.freelivedoctor.com

  38. Several methods for testing the ABO group of an individual exist. The most common method is: Serology:This is a direct detection of the ABO antigens. It is the main method used in blood transfusion centres and hospital blood banks. This form of testing involves two components: a)Antibodies that are specific at detecting a particular ABO antigen on RBCs. b)Cells that are of a known ABO group that are agglutinated by thenaturally occurring antibodies in the person's serum. www.freelivedoctor.com

  39. Illustration of the forward and reverse grouping reaction patterns of the ABO groups using a blood group tile www.freelivedoctor.com

  40. When RBCs carrying one or both antigens are exposed to the corresponding antibodies, they agglutinate; that is, clump together. People usually have antibodies against those red cell antigens that they lack. www.freelivedoctor.com

  41. Blood transfusions – who can receive blood fromwhom? People with blood group O are called "universal donors" and people with blood group AB are called "universal receivers." www.freelivedoctor.com

  42. Blood Group Antigens Antibodies Can give blood to Can receive blood from AB A B O www.freelivedoctor.com

  43. Blood Group Antigens Antibodies Can give blood to Can receive blood from AB A and B None AB AB, A, B, O A A B A and AB A and O B B A B and AB B and O O None A and B AB, A, B, O O www.freelivedoctor.com

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