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What type of antibodies does the ABO system produce during the first years of life?
What type of antibodies does the ABO system produce during the first years of life?
Why is ABO compatibility crucial in blood transfusion?
Why is ABO compatibility crucial in blood transfusion?
How are ABO antigens characterized in terms of their biological composition?
How are ABO antigens characterized in terms of their biological composition?
What is a common characteristic of the antibodies present in the ABO blood group system?
What is a common characteristic of the antibodies present in the ABO blood group system?
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At what stage of development are ABO antigens moderately well developed?
At what stage of development are ABO antigens moderately well developed?
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What other bodily fluids might contain ABO antigens besides red blood cells?
What other bodily fluids might contain ABO antigens besides red blood cells?
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What is a significant consequence of the ABO blood group system in organ transplantation?
What is a significant consequence of the ABO blood group system in organ transplantation?
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What is the nature of the A and B antigens in the ABO blood group system?
What is the nature of the A and B antigens in the ABO blood group system?
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What happens to individuals who lack A and B antigens?
What happens to individuals who lack A and B antigens?
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Which type of antibodies are ABO antibodies primarily classified as?
Which type of antibodies are ABO antibodies primarily classified as?
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At what age do ABO antibodies begin to appear in individuals?
At what age do ABO antibodies begin to appear in individuals?
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What type of genes control the ABO blood group system?
What type of genes control the ABO blood group system?
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What genotype corresponds to an individual with type O blood?
What genotype corresponds to an individual with type O blood?
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Which blood group genotype can a parent with type AB pass to their offspring?
Which blood group genotype can a parent with type AB pass to their offspring?
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What is the primary function of ABO blood group transferases?
What is the primary function of ABO blood group transferases?
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What is the characteristic of the O gene in terms of its expression?
What is the characteristic of the O gene in terms of its expression?
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What is the genotype of secretors who can produce A and B antigens?
What is the genotype of secretors who can produce A and B antigens?
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Which of these groups are considered non-secretors?
Which of these groups are considered non-secretors?
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Why is ABO grouping important for blood transfusions?
Why is ABO grouping important for blood transfusions?
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What are the two components involved in ABO typing?
What are the two components involved in ABO typing?
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In which of the following scenarios is ABO typing necessary?
In which of the following scenarios is ABO typing necessary?
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Which of the following is true regarding the Se locus?
Which of the following is true regarding the Se locus?
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What does the forward typing process in ABO typing specifically determine?
What does the forward typing process in ABO typing specifically determine?
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What is one of the uses for ABO typing in prenatal patients?
What is one of the uses for ABO typing in prenatal patients?
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What antigens are present on the surface of red blood cells for individuals with blood group AB?
What antigens are present on the surface of red blood cells for individuals with blood group AB?
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What type of antibodies are present in the serum of blood group O individuals?
What type of antibodies are present in the serum of blood group O individuals?
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Why is O Negative blood often issued in emergencies?
Why is O Negative blood often issued in emergencies?
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Which disease is more commonly associated with blood group A individuals?
Which disease is more commonly associated with blood group A individuals?
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What is a major clinical significance of ABO antibodies?
What is a major clinical significance of ABO antibodies?
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What can clerical errors during blood transfusions lead to?
What can clerical errors during blood transfusions lead to?
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Which group does not express A or B antigens on their RBCs?
Which group does not express A or B antigens on their RBCs?
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Which condition has been controversially linked to blood group O individuals?
Which condition has been controversially linked to blood group O individuals?
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What is the primary function of the H, A, and B genes in the context of blood group antigens?
What is the primary function of the H, A, and B genes in the context of blood group antigens?
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In which bodily fluids are soluble forms of ABO blood group antigens found in individuals who are 'secretors'?
In which bodily fluids are soluble forms of ABO blood group antigens found in individuals who are 'secretors'?
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Which statement correctly describes the effect of certain illnesses on a person's ABO phenotype?
Which statement correctly describes the effect of certain illnesses on a person's ABO phenotype?
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What characterizes individuals with the Bombay blood group?
What characterizes individuals with the Bombay blood group?
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How do hematological cancers affect ABO blood group antigens?
How do hematological cancers affect ABO blood group antigens?
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What is the typical range of ABO blood group antigens expressed on each human red blood cell?
What is the typical range of ABO blood group antigens expressed on each human red blood cell?
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How can an individual temporarily acquire the B antigen?
How can an individual temporarily acquire the B antigen?
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Which of the following is a subgroup of ABO blood group antigens?
Which of the following is a subgroup of ABO blood group antigens?
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Study Notes
Blood Group Systems
- A blood group system is a set of antigens that are inherited in a specific pattern
- These antigens have similar serological and physiological properties
The ABO System
- ABO IgM antibodies appear in the first few years of life
- These antibodies are a result of environmental exposure, such as bacteria, viruses, and food
- The "O" in ABO can be referred to as "0" in other languages
Importance of the ABO System
- The ABO system is the most significant blood group system when it comes to transfusions
- This is due to the pre-existing antibodies in the blood of individuals lacking the antigens
- The antibodies in the ABO system are naturally occurring and do not require prior exposure
- These antibodies are typically IgM and can readily activate the complement system
- This activation can lead to red blood cell hemolysis and even death
- Each red blood cell can harbor between 800,000 and 2 million ABO antigens
Characteristics of ABO Antigens
- ABO antigens are glycolipids that are directly attached to the red blood cell membrane
- These antigens stick out from the red cell membrane
Function of the A & B Antigens
- The function of the A and B antigens is unknown
- Individuals lacking both A and B antigens are healthy, which suggests these antigens are not essential
Characteristics of ABO Antibodies
- ABO antibodies are naturally occurring, meaning they form without exposure to the antigen
- They are primarily Immunoglobulin M (IgM) antibodies
- They react in saline and readily agglutinate
- Their optimal temperature for reaction is below 30 degrees Celsius, although reactions can occur at body temperature
- They are absent at birth and appear around 3 to 6 months of age due to bacterial polysaccharides
- ABO antibodies are typically not present in newborn blood, which is why only forward typing is performed
ABO Inheritance
- The A and B genes are located on chromosome 9
- Each individual inherits one gene from their mother and one from their father
- The A and B genes are co-dominant alleles
- This means that if an individual inherits either an A or B gene, it will be expressed
- The O gene represents the lack of the A or B antigens
- It will only be expressed if the individual inherits the O gene from both parents
- Therefore the O gene is considered recessive
ABO Inheritance Patterns
- An A/A parent can only pass along the A gene
- An A/O parent can pass along either an A or an O gene
- A B/B parent can only pass along the B gene
- A B/O parent can pass along either a B or an O gene
- An O/O parent can only pass along an O gene
- An AB parent can pass along either an A or a B gene
ABO Phenotype and Genotype
- Group A phenotype = A/A or A/O genotype
- Group B phenotype = B/B or B/O genotype
- Group O phenotype = O/O genotype
- Group AB phenotype = A/B genotype
Production of A, B, and H Antigens
- The production of A, B, and H antigens is controlled by transferases
- Transferases are enzymes that add sugar to the oligosaccharide chain
- Specific transferases are produced by the H, A, or B genes
- This results in the addition of a specific sugar to the oligosaccharide chain
Expression of ABO Antigens
- Although considered red blood cell antigens, ABO antigens can be found on various human tissues
- They are expressed on most epithelial and endothelial cells
- Each red blood cell can have between 800,000 and 2 million ABO antigens
- Other blood cells, such as T cells, B cells, and platelets, have ABO antigens absorbed from the plasma
- "Secretors" have at least one copy of the Se gene
- They secrete H antigen which, depending on their ABO genotype, is then processed into A and/or B antigens
- Non-secretors have a homozygous null allele and cannot produce soluble H antigen, therefore they do not produce A and B antigens
Expression of ABO Antigens: Illnesses
- Illnesses can alter an individual's ABO phenotype
- Bacterial infections may cause a conversion of the A1 antigen into a B-like antigen
- During these periods, patients should not receive blood products with the B antigen
- Once the infection is treated, the ABO blood group will return to normal
- Illnesses that increase the body's demand for red blood cells can weaken the expression of ABO antigens
- Hemathological cancers can also alter the sugar chains that carry the ABO blood group antigens
Bombay Blood Group
- The Bombay blood group lacks the H gene and cannot make H antigen
- H antigen is a precursor to A and B antigen, so they are also not made
- These individuals type as O and have anti-A, anti-B, and anti-H antibodies in their blood
Subgroups of A and B
- The majority (80%) of people with the A phenotype are A1
- The remaining 20% are typically A2 or A2B
- There are other, weaker subgroups of A including A3, Aint, Am, Ax, and Ael
- These variations react differently with anti-A, anti-A, and lectins
Se Locus (FUT2)
- This locus is located on chromosome 19
- The Se locus encodes a fucosyltranferease that is expressed in secretory tissues
- Secretors (Se/Se or Se/se) will secrete H antigen
- Non-secretors (se/se) lack the enzyme and cannot produce soluble H antigen
Indications for ABO Grouping
- Blood donors: To ensure the recipient does not receive incompatible blood
- Transfusion recipients: To determine if the donor blood is ABO compatible
- Organ transplant candidates and donors: since ABO antigens are found in other tissues
- Prenatal patients: To assess the likelihood of ABO HDN in the baby
- Newborn: To assess the possibility of hemolytic disease
- Paternity testing: The specific inheritance pattern provides information about paternity
ABO Typing
- This process includes antigen typing (forward typing) and antibody detection (reverse typing)
- Forward typing determines the antigens present on the individual's red blood cells
- Reverse typing determines the antibodies present in the individual's serum
Red Blood Cell Compatibility
- AB individuals have both A and B antigens and no antibodies, making them universal recipients
- O individuals lack A and B antigens but have both anti-A and anti-B antibodies, making them universal donors
- O Negative individuals have no ABO antigens and possess all ABO antibodies, making them universal donors in emergencies
Diseases Associated with ABO Blood Group Antigens
- There are no known diseases caused by the lack of ABO antigens
- The susceptibility to diseases may be linked to an individual's ABO phenotype
- Gastric cancer may be more common in group A individuals
- Gastric and duodenal ulcers may be more common in group O individuals
Clinical Significance of ABO Antibodies
- ABO antibodies are clinically significant because they are naturally occurring, universal, and highly reactive
- Transfusions: Routine blood typing and crossmatching should prevent transfusion reactions due to ABO antibodies, however clerical errors can be fatal.
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Description
Explore the essentials of blood group systems with a focus on the ABO system. Learn about the importance of ABO antigens, their immunological properties, and the implications for blood transfusions. Understand how environmental factors contribute to the development of IgM antibodies.
