Rh Blood Group System Flashcards by Jessica Dahlke

What are the 5 antigens in the Rh blood group system?

D, C, c, E, e

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What is the most common Rh phenotype?

dce

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Which chromosome are the Rh genes located?

Chromosome 1

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Which gene controls the expression of Rh antigens?

RHAg

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Which Rh gene do individuals either possess or lack?

RhD

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Which Rh gene expresses all alleles inherited - where all alleles are co-dominant?

RHCE

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What type of antibody (immune or natural) are anti-D, C, c, E, e?

Immune. Exposure must occur in order for them to form.

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What is an amorph?

Only a dominant form of the allele exists. An individual either has the gene or lacks the gene.

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Which Rh gene is an amorph?

RhD

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Which Rh antigen is the most important to test for, especially in child-bearing age women?

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What percentage of D-negative individuals who receive a single unit of D-positive blood will develop anti-D?

80%

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Which nomenclature suggested that Rh antigens were determined by 3 genes?

Fischer-Race

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Explain how Fisher-Race nomenclature suggested the inheritance of Rh genes.

The 3 Rh genes (D, C and c, E and e) occupy loci in close proximity to one another, so close that they never separate and are passed on to each generation.

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True or False: Crossing-over occurs in the Rh system.

False

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Determine the phenotype and possible genotypes of an individual that had the following antisera results:

anti-D 4+ anti-C 4+ anti-c 0 anti-E 0 anti-e 4+

Phenotype: DCe

Possible Genotypes: DCe/DCe or DCe/dCe

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Determine the phenotype and genotype of an individual that had the following antisera results:

anti-D 4+ anti-C 0 anti-c 4+ anti-E 0 anti-e 4+

Phenotype: Dce

Possible genotypes: Dce/Dce or Dce/dce

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Determine the phenotype and genotype of an individual that had the following antisera results:

anti-D 4+ anti-C 4+ anti-c 4+ anti-E 0 anti-e 4+

Phenotype: DCce

Possible Genotypes: DCe/Dce or DCe/dce or Dce/dCe

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Translate the Fischer-Race nomenclature to the Wiener nomenclature for the following:
Dce
DCe
DcE
DCE

Dce - R0
DCe - R1
DcE - R2
DCE - Rz

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Translate the Fischer-Race nomenclature to the Wiener nomenclature for the following:
dce
dCe
dcE
dCE

dce - r
dCe - r’
dcE - r’’
dCE - ry

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Which nomenclature postulated that two genes, one on each chromosome pair, controls the entire expression of the Rh system?

Wiener

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Using both the Fisher-Race and Wiener nomenclature, which genotypes are the most common for D-positive and D-negative individuals?

D-positive: R2/r - DcE/dce

D-negative: r/r - dce/dce

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Rosenfeld nomenclature is based only upon…

serologic (agglutination) reactions

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Describe how the Rosenfeld system works.

The antigens are labeled: D=1, C=2, E=3, c=4, e=5

When tested, if agglutination occurs, the number is listed as is. If no reaction occurs, a negative number is indicated.

If not tested, simply omit the number.

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Use the Rosenfeld nomenclature to describe the following results:

anti-D 4+ anti-C 0 anti-E 3+ anti-c 4+ anti-e 0

1, -2, 3, 4, -5

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How does the International Society of Blood Transfusion label blood group systems?

Via a 6 digit code First 3 numbers indicate the blood group system (004 = Rh) Second 3 numbers indicate the specific antigen (004001 = D)

Reactions with antisera only determine

phenotype

What phenotype testing is used for parentage testing, predicting HDFN, locating compatible blood for recipients, and confirming Rh antibody specificity?

Rh phenotyping

If a patient tests D-negative with anti-D, what is the next step that should be taken?

Perform a weak D test (Du)

Describe the process for weak D (Du) testing.

Incubate cells with anti-D at 37 degrees C. Wash cells 3X with saline. Add AHG to bind anti-D bound to RBCs. Agglutination = Weak D positive

List 3 mechanisms for Weak D

Genetic Mosaic Position Effect

Which mechanisms for weak D are quantitative?

Genetic | Position Effect

Which Weak D mechanism is qualitative and can be capable of producing anti-D?

Mosaic

If an individual inherits a D gene that codes for lowered densities of D antigen on RBC membranes, how will they type?

Weak D

What is the position effect?

The position of the C gene in correlation to the D gene

What is the C-trans position effect?

The C gene is on a different haplotype from the D gene Ex: DcE/dCE

What is the C-cis position effect?

The C gene is located on the same haplotype as the D gene Ex: DCE/dcE

Which position effect results in a weak-D expression due to steric hindrance?

C-trans

The absence of a portion(s) of the D antigen is termed as

Partial D (Mosaic D)

Can an individual with Partial D develop anti-D?

Yes, to the portion of the antigen that they lack.

Do normal D and Weak D have the same level of immunogenicity?

No. Weak D is substantially less immunogenic than Normal D.

Is weak D capable of producing a transfusion reaction?

Yes, in patients with anti-D

Failure to express Rh antigens on RBC surface is considered

Rh null

What are the two mechanisms can cause Rh null?

Regulator-type or amorph-type

A mutation in the RHAG gene results is what type of genetic mutation?

Regulator-type

Mutations in each of the RHCE genes inherited from each parent along with the deletion of the RHD gene is considered what type of genetic mutation?

Amorph-type

Partial suppression of Rh antigen expression is considered

Rh mod

A mutation in the RhAG gene will cause

Rh mod

In Rh null, which other antigens will test negative and which will be depressed?

negative: LW and FY5 depressed: S, s, U

Which phenotype exhibits similar clinical symptoms as Rh null, but is less severe and is rarely clinically significant?

Rh mod

Anti-LW will react more strongly in D-positive or negative individuals?

D-positive

An unusual phenotype that occurs from a single amino acid change most often found on RhCe protein

True or False: Cw can be expressed in the presence of C and c or in the absence of C and/or c.

True

The F antigen will be expressed when?

When d and c are expressed on the same haplotype

d and c are expressed on the same haplotype and the F antigen can be expressed. This occurrence can be termed...

compound antigen

rh1 phenotype occurs when

C and e are expressed on the same RhCe protein

anti-rh1 only reacts with which genotype?

DCe/dce

If an RBC expresses D and/or C, it will also express which unusual antigen?

G antigen

Anti-G can mimic

anti-C and anti-D

What occurrence can result in excess expression of the D antigen due to a lack of Cc or Ee reactivity?

deletion

D-deletion RBCs can only be transfused with

D-deletion RBCs

Rh antibodies are typically which class of Ig?

IgG

Order of Rh antigen immunogenicity

D > c > E > C > e

Rh antibodies are unable to bind

complement (due to the location on the RBC)

Most frequently encountered Rh antibody

Anti-E (followed by anti-c)

Anti-C rarely occurs by itself, but may occur in the presence of

anti-D

If anti-D is present, which other Rh antibody can be present?

anti-G (anti-D and anti-C)

R1/R1 individuals who generate anti-E will frequently also make

anti-c

Patients with anti-E should automatically be phenotyped for

c antigen

Antibodies that tend to occur together are termed

concomitant

What are the 4 types of anti-D reagent?

High protein, IgM anti-D, Chemically modified, monoclonal anti-D

Autoagglutinins, abnormal serum proteins, antibodies to additives, and using unwashed RBCs can result in false positives with which anti-D reagent?

High protein

IgG anti-D potentiated with high protein and other macromolecules

High protein anti-D

Prepared from predominantly IgM antibodies and is only used when false positives occur with high protein anti-D

IgM anti-D (low protein/saline)

Which anti-D reagent requires a diluent control?

high protein | The other reagents only require a control when AB positive

Which anti-D reagents cannot be used in the weak-D test?

IgM anti-D

IgG converted to saline agglutinin by weakening disulfide bonds at the hinge region, which produces stronger reactivity than IgM antibodies

Chemically modified anti-D

Prepared from a blend of monoclonal IgM and polyclonal IgG and is used most frequently

Monoclonal anti-D

IgM and IgG react when?

IgM - initial spin | IgG - AHG

The control diluent used for protein reagents has protein concentration equaling

human serum

What is a way you can tell if a false positive has occurred?

The forward type will appear AB positive and the control is positive

How often is QC performed on anti-D?

daily

Sources for false positives

``` spontaneous agglutination contaminated reagents use of wrong serum/reagents autoagglutinins or abnormal serum proteins coating the RBCs Not following manufacturer instructions ```

An IAT only needs to be performed only if

it is indicated in the manufacturer insert

Rh Blood Group System Flashcards

(83 cards)