Rh and LW Blood Groups

Question 1

Rh Positive

Answer 1

Presence of D antigen
Example: Group A+ means A blood type with Rh antigen
85% of population

Question 2

Rh Negative

Answer 2

Absence of D Antigen
Example: Group O- means O blood type with no Rh antigen
15% of population

Question 3

Discovery of D Antigen

Answer 3

1939-1943

Question 4

Anti D

Answer 4

Described in HDN (Hemolytic Disease of the Newborn)

Question 5

Anti-Rhesus

Answer 5

LW
Not the same as Anti D

Question 6

Rh Gene

Answer 6

Chromosome 1
Autosomal Dominant

Question 7

D antigen present

Answer 7

RBC only

Question 8

D Clinical Significance

Answer 8

Second in significance
High Immunogenicity

Question 9

Other Rh Antigens

Answer 9

Approx 50
5 most often seen - D, C, c, E, e

Question 10

Wiener Nomenclature

Answer 10

Genes indicated by single letter
Gene product: agglutinogen
Gene product + subscript: haplotype
Factors: Individual antigens

Question 11

Fisher Race Nomenclature

Answer 11

1 gene and 1 product per allele
Letter designations
Most often used

Question 12

Tippet Theory

Answer 12

Two closely linked loci
Used in research

Question 13

Fisher-Race Theory

Answer 13

Three closely linked loci inherited as a unit
Most common system

Question 14

Wiener Theory

Answer 14

Single locus with multiple alleles
Most difficult

Question 15

Rosenfield/Tippit

Answer 15

Antigens numbered in order of discovery/assignment to Rh system

Question 16

Dosage Definition

Answer 16

Amount of antigen present on homozygous cell vs amount of antigen present on heterozygous cell (weak AHG rxn)

Question 17

Genotype determination

Answer 17

Can estimate genotype based on reaction strength of phenotyping results

Question 18

R2 cells

Answer 18

cDE - one haplotype
Stronger expression of D
React more strongly with anti-D reagent
Only scenario with enhanced antigen reactions

Question 19

Cis Effect

Answer 19

Labilization of ligands that are cis to other ligands

Question 20

Cis Meaning

Answer 20

On the same side
Example: cDE - D and E are cist to each other
- E antigen produced by R2 gene (cDE) is weaker than E antigen produced by r” gene (cdE)

Question 21

Trans Effect

Answer 21

Comparison of antigens on both sides of the genotype

Question 22

Trans Meaning

Answer 22

On opposite sides
Example: C and E antigens are weaker in:
- R1(CDe)/R2(cDE) individuals C is trans with E but cis with D
- R1(Cde)/r(cde) - C is not cis or trans with either d, c, or e
- R2(cDE)/r(cde) - D is cis with E but no trans

Question 23

Possible Causes of Weak D expression

Answer 23

Due to Transmissible Gene Inheritance
- Less antigen sites
Positive Effect
- C gene in trans to D (weaker D antigen expression)
Partial D, D Mosaic, D Variant
- Lack a part of D antigen

Question 24

Weak D Notation

Answer 24

Du

Question 25

Weak D Clinical Significance for Donors

Answer 25

Weak D less immunogenic - Weak D cells destroyed by anti D

Question 26

Weak D Clinical Significance in Recipients

Answer 26

Not necessary to test for weak D - Receivin Rh neg blood doesn't affect a person

Question 27

Cis Product Antigens

Answer 27

Ce (rhi) - R1 gene (CDe)

Question 28

Ce on same haplotye

Answer 28

CDE/cde does not produce Ce (rhi)

Question 29

c and e on same haplotye

Answer 29

cDE/CDe does not have f antigen

Question 30

G Antigen

Answer 30

Present on most D pos and all C pos cells Appears to be anti C and anti D (cannot be separated) Rh neg person can make anti-G to the G antigen

Question 31

Gene Deletions

Answer 31

Rare Lack of activity at Cc and/or Ee sites Cels may show very strong D activity

Question 32

LW Antigens

Answer 32

Present on most human RBCs D neg cells have waker LW activity

Question 33

Anti LW

Answer 33

Reacts with D pos cells Weakly with D neg cells

Question 34

Rh Null

Answer 34

Very Rare No Rh antigens Absence of Regulator Gene RBC membrane abnormalitys MUST transfuse with Rh Null Blood

Question 35

Rh Antibodies

Answer 35

Anti-D Anti-C Anti-c Anti-E Anti-e

Question 36

Rh Antibodies Result

Answer 36

Immunization (exposure) Immunogenicity e

Question 37

False Positives in Rh Testing

Answer 37

Wrong reagent added Contaminating Antibody Polyagglutinable RBCs Autoagglutinins/Abnormal Proteins (Multiple Myeloma) Contaminated Reagent

Question 38

False Negatives in Rh Testing

Answer 38

Wrong Reagent Added Reagent Not Added Variant Antigen Procedural Weak Agglutination Contaminated Reagent

Question 39

When is it necessary to use an Rh (D) control?

Answer 39

Using High protein anti-D reagent (albumin)

Question 40

What situations would cause a false positive reaction when doing Du testing?

Answer 40

Individual who has a positive DAT Rh negative mother who has experienced a large fetal-maternal hemorrhage from Rh positive child

Question 41

What is the best way to elminate cell agglutination due to Wharton's Jelly?

Answer 41

Wash cells multiple times (4-5)

Question 42

What are the possible causes of the following reactions: patient cells + anti-D: 3+ patient cells + Rh control: 2+

Answer 42

Positive DAT Rouleaux

Question 43

What are the possible causes of the following reactions: patient cells + anti-D: 0 above tube + anti IgG AHG: 0 above tube + Coombs Check Cells: 0

Answer 43

Rh type cannot be determined Inadequate washing of cells may have occurred Inactive AHG reagent

Question 44

Rh testing and obtain the following results: patient cells + anti-D: 3+ patient cells + Rh control: 3+ What is the next course of action?

Answer 44

Repeat the Rh typing with saline D or a chemically modified D antisera

Question 45

An 18 yr old female is admitted to ER following a serious accident. She has had no pregnancies, no history of transfusion, and is on no mediation. Her ABO/Rh testing: patient cells + anti-A: 3+ patient cells + anti-B: 0 patient cells + anti-A,B: 3+ patient cells + anti D: 0 this tube + anti IgG AHG: 2+ patient cells + Rh Control: 0 this tube + anti IgG AHG: 0 Tube + CC: 2+ patient serum + A1 cells: 0 patient serum + B cells: 3 +

Answer 45

Patient is weak D positive, report as Rh pos

Question 46

Red cells type as weak D (Du) positive. The phenotype results follow. What is the most likely genotype? Anti-C: 2+ Anti-c: 2+ Anti-E: 0 Anti-e: 2+

Answer 46

DCe/dce

Question 47

A patient is found to be Group O, Rh positive. They also have an anti-c in their serum. What is the most probable genotype of this patient? What type of blood must be transfused to this patient?

Answer 47

DCe/DCe; must be transfused with blood that is c negative