Rh Blood Group System and Hemolytic Disease
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Questions and Answers

What discovery led to the identification of the Rh blood group system?

  • Observation of agglutination reactions with ABO antibodies.
  • Investigation of transfusion reactions in patients with matching ABO types.
  • The study of Rhesus macaque monkey erythrocytes.
  • The investigation of Hemolytic Disease of the Fetus and Newborn. (correct)

How are the RHD and RHCE genes arranged on Chromosome 1, according to current genetic theory?

  • They are located far apart on the same chromosome.
  • They are located on different chromosomes that assort independently during meiosis.
  • They are independently transcribed.
  • They are closely linked at different loci and considered to be a haplotype. (correct)

What is the role of the RHAG glycoprotein in the expression of Rh antigens?

  • It independently determines the expression levels of D and CE antigens.
  • It directly produces the D and CE antigens.
  • It is essential for the expression of RHD and RHCE antigens, acting as a co-expressor. (correct)
  • It modifies the D and CE antigens.

What is the consequence of lacking the Rh glycoprotein in red blood cells?

<p>Red cell morphology abnormality known as stomatocytosis. (C)</p> Signup and view all the answers

What is the key difference in the genetic control of Rh antigens between the Fisher-Race and the current genetic theories?

<p>The Fisher-Race theory posits three closely linked genes, whereas the current theory proposes two genes. (A)</p> Signup and view all the answers

What is the significance of the 103rd and 226th amino acids in the RHCE protein?

<p>They dictate whether the C/c and E/e antigens are expressed, respectively. (D)</p> Signup and view all the answers

In the Rosenfield nomenclature, what does the arrangement 'Rh: 1, 2, -3, 4, 5' indicate?

<p>The individual is positive for D, C, c, and e antigens, but negative for E antigen. (B)</p> Signup and view all the answers

What is the primary reason Rh antigens are particularly significant in Hemolytic Disease of the Fetus and Newborn (HDFN)?

<p>They are well-developed early in fetal life. (A)</p> Signup and view all the answers

What is the typical antibody response following exposure to Rh-positive red cells?

<p>IgM followed by IgG (A)</p> Signup and view all the answers

Why is hemolysis in Rh-mediated reactions typically extravascular?

<p>Rh antigens disperse themselves, preventing complement activation. (B)</p> Signup and view all the answers

How does Weak D expression impact routine blood bank procedures?

<p>Differentiation is not made serologically. (A)</p> Signup and view all the answers

What distinguishes Partial D from Weak D?

<p>Partial D lacks one or more D antigen epitopes, while Weak D has reduced D expression. (A)</p> Signup and view all the answers

Why might a 'D Positive' individual produce an Anti-D antibody?

<p>They have a Partial D phenotype and are missing some D epitopes. (C)</p> Signup and view all the answers

What is the correct course of action if an individual with a Partial D requires a blood transfusion?

<p>Transfuse D-positive red cells, as they are still considered D positive. (C)</p> Signup and view all the answers

What is the purpose of adding Coombs check cells to a negative IAT result in Rh testing?

<p>To ensure the AHG reagent. (A)</p> Signup and view all the answers

What does a positive DAT result indicate when performing an IAT for Weak D?

<p>The red cells are already sensitized in vivo. (D)</p> Signup and view all the answers

What is indicated when there is no agglutination upon the addition of Coombs check cells during IAT testing?

<p>It means the AHG was neutralized or is expired, and the results are invalidated. (C)</p> Signup and view all the answers

What does 'C TRANS' refer to regarding Weak D expression?

<p>The RHD gene located is on the opposite chromosome from the RHCE gene. (A)</p> Signup and view all the answers

What might -D- deletion phenotypes indicate regarding Rh antigen expression?

<p>Absence of C and E antigens. (C)</p> Signup and view all the answers

How does Rh null differ from Rh negative?

<p>Rh null lacks all Rh antigens, whereas Rh negative lacks the D antigen. (C)</p> Signup and view all the answers

Which Rh antibody is most often associated with causing Hemolytic Disease of the Fetus and Newborn (HDFN)?

<p>Anti-c (B)</p> Signup and view all the answers

What is the characteristic of antibodies to low-frequency antigens like Cw?

<p>They often accompany other antibodies. (C)</p> Signup and view all the answers

What is the significance of the G antigen concerning Rh antibodies?

<p>It is present in most D+ and C+ cells, causing D+ patients to produce Anti-C. (D)</p> Signup and view all the answers

Which antibody is produced uniquely by Rhnull individuals?

<p>Anti-total Rh (A)</p> Signup and view all the answers

In deletion phenotypes like -D- or D--, what clinical challenge do patients face if they require a transfusion?

<p>They require Rh null blood for transfusion. (D)</p> Signup and view all the answers

What is the typical characteristic of the LW blood group system concerning its reactivity with Rh antigens?

<p>Anti-LW reacts strongly with D positive red cells. (A)</p> Signup and view all the answers

How similar are the Rh and the LW blood group systems?

<p>They are similar serologically, but different genetically. (C)</p> Signup and view all the answers

What is the main characteristic of the LWª antigen?

<p>It is present usually on all red cells. (C)</p> Signup and view all the answers

Which description aligns with how IgG1 and IgG3 antibodies affect red blood cells?

<p>Sensitized red cells are easily eliminated. (D)</p> Signup and view all the answers

What is the function of saline when performing an IAT?

<p>To eliminate bounding antibodies. (D)</p> Signup and view all the answers

What is the difference between the Fisher-Race and Weiner nomenclatures?

<p>Weiner's theory uses one gene, while Fisher-Race's uses three. (C)</p> Signup and view all the answers

What would be the Fisher-Race nomenclature, if the Weiner nomenclature says that the mother is R2 and the father is r?

<p>DcE and dce. (C)</p> Signup and view all the answers

Why does it help to know history while in the lab?

<p>History determines how the blood groups are classified. (D)</p> Signup and view all the answers

What do D positive and D negative results mean?

<p>One has the antigen while the other does not. (B)</p> Signup and view all the answers

If both an RHD and RHCE gene are tested, what two results will be found?

<p>4 combinations of D and ce. (D)</p> Signup and view all the answers

What is the role of genes and what do they affect?

<p>They are essential for testing. (A)</p> Signup and view all the answers

What do Rho, hr', hr” have in common?

<p>They are short designations for blood factors in the Weiner system. (C)</p> Signup and view all the answers

What process occurs if someone who is Rh negative has 0.1mL of Rh positive cells?

<p>Antibody production starts. (A)</p> Signup and view all the answers

What is the significance of the D>c>E>C>e acronym?

<p>They demonstrate most to least immunogenicity. (B)</p> Signup and view all the answers

How does the absence of the RHAG gene affect the expression of RHD and RHCE antigens?

<p>It can affect the expression of RHD and RHCE antigens. (B)</p> Signup and view all the answers

What is the primary structural characteristic of the RH glycoprotein within the red cell membrane?

<p>It consists of 416 amino acids that traverse the plasma membrane 12 times. (C)</p> Signup and view all the answers

How does the 'C TRANS' mechanism lead to Weak D expression?

<p>The RHCE gene on the opposite chromosome influences and weakens the expression of the D antigen. (D)</p> Signup and view all the answers

What is the correct course of action when a patient with a Partial D phenotype requires a blood transfusion?

<p>Transfuse with D-positive red cells, as the patient still expresses some D antigen epitopes. (B)</p> Signup and view all the answers

What is indicated if the Indirect Antiglobulin Test (IAT) is negative, but there is no agglutination upon adding Coombs check cells?

<p>The test result is invalid and must be repeated. (C)</p> Signup and view all the answers

Flashcards

HDFN & Rh BGS

Hemolytic Disease of the Fetus and Newborn linked to Rh BGS.

RHD and RHCE genes

Located on Chromosome 1, responsible for producing Rh antigens.

RHAG

A glycoprotein, not an antigen, essential for Rh antigen expression.

RH Glycoprotein

416 amino acids, traversing the plasma membrane 12 times

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Stomatocytosis

Red blood cell morphology abnormality due to the absence of Rh glycoprotein.

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Capital C antigen

Serine at amino acid position 103

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Small c antigen

Proline at amino acid position 103

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Capital E antigen

Proline at amino acid position 226

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Small e antigen

Alanine at amino acid position 226

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Fisher-Race Genetic Theory

Nomenclature with three genes on three loci, but close together

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'd' Antigen

Denotes the absence of D antigen.

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Rhnull (amorph)

No Rh antigens present including D

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Rhmod (modified)

Rh antigens weakened, not completely absent.

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Weiner Genetic Theory

One gene codes for three combinations.

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Agglutinogen

Synonym for immunogen, also known as Antigen.

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Agglutinin

Synonym for Antibody, also known as Immunoglobulin.

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Rosenfield Numeric

In order: D, C, E, c, e

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ISBT numbering

004

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Rh Antigen Quantity

D>c> E >C>e

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IgG Subclasses

IgG1 and IgG3

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Rh Antigen Separation

Exravascular hemolysis because dispersed antigens inhibit complement binding

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Antibody transition with

D antigen

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Du phenotype

Weak D expression was historically known as:

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Weak D Mechanisms

Genetic Weak D, C Trans, and Partial D.

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Genetic Weak D

Defective RHD gene codes for weaker D

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Genetic Weak D Discovery

Requires IAT (Indirect Antiglobulin Test).

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CIS position effect

RhD and RhCe are on the same chromosome.

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C in TRANS discovery

Requires IAT (Indirect Antiglobulin Test).

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Partial D (D Mosaic)

One or more missing or altered epitopes of D antigen.

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Partial D Make Anti-D

YES, Antibody to missing epitope

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Weak D Testing Step #1

Label 2 tubes as Anti-D and Rh control.

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IAT (testing)

Perform IAT (Indirect Coombs Test) to detect in vitro sensitization.

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Coombs Check Cells

Red cells sensitized with IgG.

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DAT Test - Result

Positive for DAT, Px's red cells already sensitized IN VIVO.

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IAT -Result

Anti-D UNABLE to attach because reaction occurred

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Testing

Cannot have any testing because of antibodies present

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Variant Ag

Cis product ag; present when C and e are inherited as haplotype

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What phenotype can it be

Deletion Phenotype -D- or D-

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Can the RH-Negative cells effect the posotive?

Rh-negative woman and Rh-positive man conceive a child

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The LW Blood Group System Chromosome

Chromosome 19

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LW

Amorph gene: LW

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Clinically significant and rafe

Reacts strongly with D positive red cells

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Study Notes

  • In 1940, the Rh blood group system’s link to Hemolytic Disease of the Fetus and Newborn (HDFN) was discovered by Levine and Stetson.
  • Rh antigens derive from experiments with 'Rhesus monkey cells'.
  • These cells were obtained from a woman who had a stillborn baby as her second child.
  • During the woman's delivery, she received a blood transfusion from her husband, who had the same ABO type.
  • A hemolytic transfusion reaction still occurred, leading to the discovery that the baby and the father possessed an antigen absent in the mother.
  • The mother produced an antibody against this antigen, causing the baby's death during the second pregnancy before 6 months.
  • The Landsteiner and Weiner experiments showed that injecting Rhesus monkey red cells into guinea pigs and rabbits resulted in antibody production.
  • These antibodies identified a new blood group system, named Rh.
  • HDFN mother antibodies and guinea pig/rabbit antibodies infused with Rhesus monkey cells are similar, but not identical and attack one antigen.
  • The name Rh was retained for human antigens, while antibodies from guinea pigs/rabbits were referred to as Lw antibodies (Landsteiner and Weiner).
  • Nomenclature is based on Rh antigen creation.
  • There are three genetic theories explaining Rh antigen production.

Inheritance: Current Rh Genetic Theory

  • The RHD and RHCE genes are linked on Chromosome 1.
  • The genes responsible for Rh antigens are found on Chromosome 1.
  • The current genetic theory states that two genes create Rh antigens.
  • The RHD gene has allele D, producing the D positive antigen.
  • The RHCE gene has alleles RHCE, RHCe, RHcE, and Rhce, producing antigens CE, Ce, cE, and ce which have to be C and E.
  • D gene combines with the CE gene to form antigen combinations DCE, DCe, DcE, and Dce.

RHAG

  • RHAG is located on Chromosome 6 and functions as a coexpressor.
  • RHAG is involved in the RHAG glycoprotein production.
  • RHAG is not itself an antigen, but a related glycoprotein.
  • RHD and RHCE antigen expression is dependent on the RHAG gene, but its expression is independent of product expression.
  • Rh antigens reside in the RH glycoprotein, which consists of 416 amino acids and traverses the plasma membrane twelve times, providing stability.

Rh null

  • Individuals lacking the Rh glycoprotein due to being Rh null experience stomatocytosis, an RBC morphology abnormality.
  • RHD positive individuals do not experience stomatocytosis.

Differences in Amino Acid Sequence

  • The 103 Cc amino acid influences capital/small C antigens where SERINE yields capital C, and PROLINE yields small c.
  • The 226 Ee amino acid codes for E, where PROLINE yields capital E and ALANINE yields small e.

DCE Terminology

  • The “d” antigen does not exist and indicates the absence of the D antigen.
  • Deletion phenotypes occur when particular genes are deleted with a D antigen
  • D- or DE means the C is deleted
  • CD- or cd- means the E is deleted
  • D- (Double deletion) means there are no C or E
  • Rhnull or -/- means there are no Rh antigens
  • In Rh-, only D is absent while C and E are present
  • In Rhnull, all antigens are absent
  • In Rhmod, expression is weakened for D, C, and e to modifications or due those of coexpressor RHAG.

Fisher-Race Genetic Theory

  • One of the two major Rh nomenclatures
  • There are different genes that produces D, C or c, and E or e

Weiner Genetic Theory

  • Alleles include R0, R1, R2, RZ, r, r’, r’’, ry
  • One gene codes for three combinations of D, C, and E.

Application

  • Genes are written in italics and superscript in Weiner's theory. Agglutinogen is synonymous with Antigen.
  • Agglutinin refers to the Antibody.
  • Immunogen is the same as Ab (Immunoglobulin). Capital R is written as a subscript.

Rosenfield Numeric Technology

  • The arrangement is D C E c e or 1 2 3 4 5
  • Write Rh: followed by the Rosenfield terminology without skipping that step

Antigens - Well Developed Early In Fetal Life

  • The antigen list is D>c> E >C>e
  • Exposure to at least 1 mL of Rh positive cells would stimulate antibody production of Rh negative persons

Antibodies

  • IgG1, IgG2, IgG3, IgG4 have all been reported
  • Do not bind complement.
  • antibody transition will always start with IgM then develop to IgG

Four forms of IgG antibodies

  • Rh antibodies are found in all four forms
  • IgG1 and IgG3 sensitized red cells are easily eliminated by reticuloendothelial
  • System.

Four forms of IgG antibodies

  • 2 IgGs that are adjacent to each other can activate complement
  • IF they are separated, they cannot activate complement
  • Rh antigens dispersed in the plasma membrane cannot stick and cause majority of hemolysis to be extravascular

Blood Factors

  • There is no designation for Absence of D antigen
  • Mainly that because they re well developed early in utero.

Variants of the Rho (D) Antigen Expression

  • There is weak D in which the presence of D is apparent but DECREASED.
  • Also known as Du positive

D expression

  • Genetic Weak D
  • C trans
  • Partial D Regardless, serological testing are same with D.
  • Can be differentiated with genetic testing.

1- Genetic Weak D

  • Genetic weakness D means Defective GENE
  • RHD genes code for weaker expression of D antigen
  • Because it is mutated that there is reduced D antigens

IAT

  • IAT (Indirect Antiglobulin Test Required for donors who are initially typed as D negative

Partial D (D Mosaic

  • The individual has other epitopes of the D antigen either strongly or weakly and these will still REACT WITH ANTI -D
  • They STILL HAVE “D”antigen
  • They are D POSITIVE
  • They SHOULD REQUIRES transfusion D POSITIVE or a person with D Positive can be transfused to another D positive.

IF THE PERSON HAS A MISSING EPITOPE BUT STILL REACTS WITH ANTI –D ,THEY ARE STILL CONSIDERED TO BE “D”POSITIVE!

Unusual Phenotypes And Rare Allele Types

  • Unusual antibody would be RH 29 or total RH D - that they cannot live
  • If Anti-Rh is detected, Rhnull cells are needed for transfusion
  • Partial suppression of Rh, that the reason to modified RHAC gene

Hemolytic Disease of the Fetus and Newborn

  • RH NEGATIVE Women can lead woman being RH positive that fetus cells enter the mother with RH positive blood cells

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Description

Discovery of Rh blood group system in 1940 linked it to Hemolytic Disease of the Fetus and Newborn (HDFN). Experiments injecting Rhesus monkey red cells into guinea pigs and rabbits led to antibody production and identification of the Rh system. HDFN involves mother antibodies reacting to fetal antigens.

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