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CHAPTER
S T U DY A I D A N S W E R S
10
THE Rh BLOOD GROUP SYSTEM
TONY CASINA AND EVA D. QUINLEY
10-1.
AntiD
C
E
0
c
e
Wiener
Fisher–Race
Rosenfield
0
0
R1R1 or R1r
DCe/DCe DCe/Ce
Rh: 1, 2, 3, 4, 5
0
R2R2 or R2r
DcE/DcE or DcE/cE
Rh: 1, 2, 3, 4, 5
0
R2R2 or R2r
or R2ry
DcE/DcE or DCE/cE
or DcE/CE
Rh: 1, 2, 3, 4, 5
0
0
R0R0 or R0r
Dce/Dce or Dce/ce
Rh: 1, 2, 3, 4, 5
R1R2 or RzR0 or
Rzr or R2r or
R1r or R0ry
DCe/DcE or DCE/Dce
or DCE/ce or DcE/Ce
or DCe/cE or Dce/CE
Rh: 1, 2, 3, 4, 5
0
0
RzRz or Rzry
DCE/DCE or DCE/CE
Rh: 1, 2, 3, 4, 5
0
0
0
rr
ce/ce
Rh: 1, 2, 3, 4, 5
0
0
rr
cE/ce
Rh: 1, 2, 3, 4, 5
0
0
rr
Ce/ce
Rh: 1, 2, 3, 4, 5
10-2. Of the genotypes listed in the above table,
which one is most common in the Caucasian
population? R1r Which one is least common?
RzRz
10-3. a, c, d
5
10-4. _____
2
_____
1
_____
4
_____
3
_____
R1R2
Dc–/Dc–
–D–/–D–
R1R1
R2R2
10-5. 1) Mother: R1R1 or R1r⬘
Father: RzR0 or R2r or R1R2 or R2r⬘ or R1r⬙
or R0ry
2) Mother: R1R1
Father: R1R2
3)
R1
R1
R1
R1R1
R1R1
R2
R1R2
R1R2
50% of offspring would be R1R1
50% of offspring would be R1R2
4) There are three possible explanations. One is
nonpaternity. A second explanation is that
the Rh type of this offspring may be due to
an amorph Rh gene inherited from the
mother. The mother’s haplotype may be
R1/– – –. In this case, the offspring would
type as R2 with a haplotype of R2/– – –. The
amorph type of inheritance will continue to
be passed to the offspring, resulting in apparent homozygous expression of the Rh genotype. A third possible explanation is that the
Rh type of this offspring is due to an Rh
“regulator” gene. In this case, the parents
would have normal expression of the Rh
antigens but be heterozygous for the RHAG
gene. If each parent passed the RHAG gene
mutation to the offspring, Rh antigen production would be blocked. The offspring
would be negative for all Rh antigens (i.e.,
Rhnull). Because the offspring in question has
expressed DcE antigens, the most likely explanation is the “amorph” inheritance.
5) Because positive reactions were noted with
all Rh antisera tested, a control was tested to
eliminate the possibility of false-positive reactions. Alternatively, the DAT could have
been performed. It is best to consult the package insert for the antisera to determine the
most appropriate control and when it should
be tested.
10-6. • The wrong sample was collected and tested
• Technical error (e.g., wrong reagent, improper
technique, not following package insert)
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UNIT 4 Red Blood Cell Groups and HLA
• Reagent anti-D is different than that used
previously and results differ (polyclonal
vs. monoclonal or different monoclonal
reagent with different clones)
• Deterioration of reagent anti-D
10-7. The most likely explanation is that the patient
has a partial D antigen and has made antibodies
against the missing components of the D antigen. The patient is weakly reactive with reagent
anti-D, indicating that some D antigen is present
but in a smaller quantity than expected. Because the patient has been transfused, it is possible to form antibodies against the missing
component of the D antigen. Additional testing
with special antisera or testing by nucleic acid
analysis would be required to help identify the
type of partial D.