4.3 Rh Blood Group System Flashcards
** A complete Rh typing for antigens C, c, D, E, and e revealed negative results for C, D, and E. How is the individual designated?**
A. Rh positive
B. Rh negative
C. Positive for c and e
D. Impossible to determine
B. Rh negative
Rh positive refers to the presence of D antigen; Rh negative refers to the absence of D antigen. These designations are for D antigen only and do not involve other Rh antigens.
How is an individual with genotype Dce/dce classified?
A. Rh positive
B. Rh negative
C. Rh null
D. Total Rh
A. Rh positive
This individual has D antigen and is classified as Rh positive. Any genotype containing D antigen will be considered Rh positive.
If a patient has a positive DAT, should you perform a weak D test on the cells?
A. No, the cells are already coated with antibody
B. No, the cells are Rh null
C. Yes, the immunoglobulin will not interfere with the test
D. Yes, Rh reagents are enhanced in protein media
A. No, the cells are already coated with antibody
If a person has a positive DAT, the RBCs are coated with immunoglobulin. If a test for weak D were performed, the test would yield positive results independent of the presence or absence of D antigen on the RBCs.
Which donor unit is selected for a recipient with anti-c?
A. r’r
B. R0R1
C. R2r’
D. r’ry
D. r’ry
The designation r’ is dCe and ry is dCE, neither of which contains c antigen. The other three Rh types contain c antigen and could not be used in transfusion for a person with anti-c.
Which genotype usually shows the strongest reaction with anti-D?
A. DCE/DCE
B. Dce/dCe
C. D-/D-
D. -CE/-ce
C. D-/D-
The phenotype that results from D-/D- is classified as enhanced D because it shows a stronger reaction than expected with anti-D. Such cells have a greater amount of D antigen than normal. This is though to result from a larger quanitity of precursors being abailable to the D genes because there is no competition from other Rh genes.
Why is testing for Rh antigens and antibodies different from ABO testing?
A. ABO reactions are primarily caused by IgM antibodies and usually occur at room temperature; Rh antibodies are IgG and agglutination usually requires a 37C incubation and enhancement media
B. ABO antigens are attached to receptors on the outside of the RBC and do not require any special enhancement for testing; Rh antigens are loosely attachedd to the RBC membrane and require enhancement for ddetection
C. Both ABO and Rh antigens and antibodies have similar structures, but Rh antibodies are configured so that special techniques are needed to facilitate binding to Rh antigens
D. There is no difference in ABO and Rh testing; both may be conducted at room temperature with no special enhancement needed for reaction.
A. ABO reactions are primarily caused by IgM antibodies and usually occur at room temperature; Rh antibodies are IgG and agglutination usually requires a 37C incubation and enhancement media
Detection of ABO and Rh antigens and antibodies requires different reaction conditions. ABO antibodies are naturally occuring IgM molecules and react best at room temperature. Rh antibodies are generally immune IgG molecules that result from transfusion or pregnancy. Detection may require 37 C incubation and/or enhancement techniques.
Testing reveals a weak D that reacts 1+ after indirect antiglobulin testing (IAT). How is this result classified?
A. Rh-positive
B. Rh-negative, Du positive
C. Rh-negative
D. Rh-positive, Du positive
A. Rh-positive
Blood tested for weak D that shows 1+ reaction after IAT is classified as Rh positive. The weak D designation is not noted in the reporting of the result.
What is one possible genotype for a patient who develops anti-C antibody?
A. R1r
B. R1R1
C. r’r
D. rr
D. rr
Only rr (dce/dce) does not contain C antigen. A person will form alloantibodies only to the antigens he or she lacks.
A patient developed a combination of Rh antibodies: anti-C, anti-E, and anti-D. Can compatible blood be found for this patient?
A. It is almost impossible to find blood lacking C, E, and D antigens
B. rr blood could be used without causing a problem
C. R0R0 may be used because it lacks all three antigens
D. Although rare, ryr blood may be obtained from close relatives of the patient
B. rr blood could be used without causing a problem
The genotype rr ( dce/dce) lacks D, C, and E antigens and would be suitable for an individual who has developed antibodies to all three antigens. This is the most common Rh-negative genotype and is found in nearly 14% of blood donors who are white.
A patient tests positive for weak D but also appears to have anti-D in his serum. What may be the problem?
A. Mixup of samples or testing error
B. Most weak D individuals make anti-D
C. The problem could be caused by a disease state
D. A D mosaic may make antibodies to missing antigen parts
D. A D mosaic may make antibodies to missing antigen parts
The D antigen comprises different parts designated as a mosaic. If an individual lacks parts of the antigen, he or she may make antibodies to the missing parts if exposed to the whole D antigen.
Which offspring is not possible from a mother who is R1R2 and a father who is R1r?
A. DcE/DcE
B. Dce/DCe
C. DcE/DCe
D. Dce/dce
A. DcE/DcE
DcE/DcE (R2R2) is not possible because R2 can be inherited only from the mother and is not present in the father.
Which weak D phenotypes necessitate Rh immune globulin (RhIg) prophylaxis?
A. 1
B. 2
C. 3
D. None of the above
D. None of the above
Weak D phenotypes 1, 2, and 3 (as well as 4) are not associated with formation of anti-D negating RhIg prophylaxis. Weak D phenotypes 5, 11, 15, 19, and 20 would require RhIg prophylaxis.
What antibodies could an R1R1 make if exposed to R2R2 blood?
A. Anti-e and anti-C
B. Anti-E and anti-c
C. Anti-E and anti-C
D. Anti-e and anti-c
B. Anti-E and anti-c
The R1R1 (DCe/DCe) individual does not have the E or c antigen, and could make anti-E and anti-c antibodies when exposed to R2R2 cells (DcE/DcE).
What does the genotype -/- represent in the Rh system?
A. Rh negative
B. D mosaic
C. Rh null
D. Total Rh
C. Rh null
A person who is Rh null shows no Rh antigens on his or her RBCs. Loss of Rh antigens is very unlikely to happen beause Rh antigens are integral parts of the RBC membrane. The Rh null phenotype can result from either genetic suppression of the Rh genes or inheritane of amorphic genes at the Rh locus.
What techniques are necessary for weak D testing?
A. Saline + 22C incubation
B. Albumin or LISS + 37C incubation
C. Saline + 37C incubation
D. 37C incubation + IAT
D. 37C incubation + IAT
Weak D testing requires both 37 C incubation and the IAT procedure. Anti-D is an IgG antibody, and attachment of the D antigen is optimized at warmer temperatures. AHG in the IAT phase facilitates lattice formation by binding to the antigen-antibody complexes.