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BBNK 101-1 - ABO Blood Group
68k - 01 - BBNK 101-1 - ABO Blood Group
38
Medical
Not Applicable
02/15/2012

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Term
Antigen
Definition
Substance that is capable of eliciting an immune response when introduced in-vivo.
Term
Antibody
Definition
Protein substance secreted by plasma cells in response to, and interacting sepcefically with an antigen.
Term
Antigenicity
Definition
The ability of antigens to stimulate an immune response.
Term
Gene
Definition
Biological unit of heredity, located at a definite position on a particular chromosome.
Term
Locus/Loci
Definition
Specific location of a gene on a given chromosome.
Term
Genotype
Definition
Listing of genes actually found on a pair of chromosomes.
Term
Phenotype
Definition
Listing of antigens expressed.
Term
Allele
Definition
Alternate form of a series of genes that occupy a single locus on either of a pair of chromosomes.
Term
Linked Genes
Definition
Gene loci located so close together they are inherited together as a single unit.
Term
Homozygous Genes
Definition
Two identical genes in a gene pair.
Term
Heterozygous Genes
Definition
Two unlike genes (alleles) in a gene pair.
Term
Dominant Gene
Definition

A trait or characteristic that will be expressed in the offspring even though it is only carried on one of the homologous chromosomes.

 

For example, If only one gene in a heterozygous gene pair is expressed, the expressed gene is considered to be dominant.

Term
Recessive Gene
Definition

A type of gene that, in the presence of it's dominant allele, does not express itself; expression occurs when it is inherited in the homozygous state.

 

If one gene in a heterozygous gene pair is not expressed it is considered to be recessive.  Recessive genes are only expressed as phenotypes when they occur as a homozygous gene pair.

Term
Co-dominant Gene
Definition
Charachteristics determined by the genes on both chromosomes are both expressed - either is dominant over the other i.e. A/B types as AB
Term
Amorphic Genes
Definition
A gene that does not cause production or expression of anything.
Term
Naturally Occurring
Definition
Antibodies produced without exposure to an antigen.  Also called iso-antibodies.
Term
Who discovered the ABO system and when?
Definition
Karl Landsteiner - 1900
Term
Biochemical Structure of the ABO Blood Group Antigens.
Definition

A backbone molecule inserts into the RBC membrane.

  • Four terminal sugars of the backbone.
    • Glucose
    • L-Fructose
    • N-Acetylglucosamine
    • D-Galactose
  • The backbone exists in four forms, two of which are predominantly seen.
    • Type I
    • Type II
Term
In the biochemical structure of the ABO blood group antigens, what are the four terminal sugars of the backbone?
Definition
  • Glucose
  • L-fructose
  • N-acetylglucosamine
  • D-galactose
Term
In the biochemical structure of the ABO blood group antigens, the backbone exists in how many forms, and which two are predominantly seen?
Definition

There are four forms,

Type I and Type II are predominantly seen.

Term
The genetic structure of the ABO blood group antigens.
Definition

The H system has two genes H and h, and one antigen, H, which serves as the precursor molecule on which A and B antigens are built.

On group O red cells, the H antigen is not converted into A or B antigen, and the membrane expresses abundant H.

  • Hh locus on chromosome #19
  • ABO locus on chromosome #9
Term
Which gene is necessary for the formation of A and B antigens?
Definition
The H gene
Term
The H gene
Definition

causes production of L-fucosyl-transferase which binds L-fucose to the Type II chain creating the ABO precursor.

 

The H gene is necessary for the formation of A and B antigens.

Term
Which gene is a rare Amorph that produces no enzyme?
Definition
The h gene
Term
Which genotype is extremely rare and is called Bombay?
Definition
The hh genotype
Term
Bombay cells
Definition
  • Bombay cells cannot be converted to group A or B by the specific transferases.
  • Bombay cells fail to react with anti-A and anti-B and anti-H.
  • Bombay individuals can only be transfused with other Bombay cells because of the anti-H
Term
The A Gene
Definition
Causes production of N-acetylgalactosamine to the ABO precursor.
Term
The B Gene
Definition
This causes production of galactosyl transferase, which bonds D-galactose to the ABO precursor.
Term
The O Gene
Definition
An Amorph, no enzyme or product expressed.  The H antigen remains unchanged.
Term
Genetic Structure of the ABO Blood Group Antigens
Definition
Each person inherits one gene (A, B, O) from each parent. A and B genes are co-dominant to each other, and dominate the O amorphic gene.
Term
What are four subgroups of ABO phenotypes that differ in the amount of antigen carried on red cells?  These subgroups represent 99% of all A subgroups.
Definition

A1 - Most common

A2 - Second most common

A3 - Third most common

Aint - intermediate between A1 & A2

Term
Charachteristics of the A subgroups.
Definition

All A subgroups are made from a type II backbone.

The subgroups differ in the amount of A antigen that they have. (A1 - most/A3 - least)

A cell that has small amounts of A antigen (A3) will have large ammounts of H antigens.

Term
What are two types of Hemolytic Transfusion Reactions (HTRs)?
Definition
Immediate & Delayed
Term
What diseases affect ABO antigens?
Definition
  • leukemia depresses antigen expression/strength
  • Carcinoma of the stomach or pancreas can cause the antigens to be undetectable.
  • Diseases that can cause Acquired "B" phenomenon.
Term
What are the diseases that affect the ABO antibodies?
Definition

Various Lymphomas, i.e. malignant non-Hodgkin's

Very young / elderly patients.

immunosuppressant therapy

Term
What is forward typing?
Definition
Patient cells are exposed to known antibodies in commercially prepared antisera.
Term
What is Reverse Typing?
Definition
When patient serum is exposed to commercially prepared red cells containing known antigens.
Term
What are the four Non-Technical ABO discrepancies?
Definition

Group 1 - antibodies

Group 2 - antigens

Group 3 - proteins

Group 4 - Misc.

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