RH Flashcards
The genes that control the system are located in chromosome 1
● Polymorphic
RH
In RH blood group, Only the most clinically significant will be emphasized
D, C, E, c, and e
can cause transfusion reactions and hemolytic disease of the newborn (HDN)/Erythroblastosis fetalis
D ANTIBODY
defined D antigen (Rh factor)
1939 Levine and Stetson
discovered anti-Rh (named after Rhesus monkey)
1940 Landsteiner and Wiener
RH ANTIGEN FREQUENCY
● D antigen – 85%
● C antigen – 70%
● c antigen – 80%
● E antigen – 30%
● e antigen – 98%
determines the expression of the D antigen
RHD gene
determines the expression of the C, c, E, and e
antigens
RHCE gene
are an integral part of the red cell membrane.
Rh antigens
systems of nomenclature that theorize the inheritance of the Rh system
○ 1: Fisher-Race
○ 2: Wiener
○ 3: Rosenfield
○ 4: International Society of Blood Transfusion (ISBT)
The terminology used to describe the Rh system is derived from 4 sets of investigators
○ The first two of the terminologies are based on the postulated genetic mechanisms of the Rh system.
○ The 3rd terminology describes only the presence or absence of a given antigen.
○ 4th is result of the effort of the International Society of Blood Transfusion (ISBT) Working Party on Terminology for Red cell Surface antigens
Most commonly used nomenclature
Fisher-Race
Who developed fischer-race nomenclature
Ronald Fisher and Robert Race of England
Rh-Hr terminology
Weiner
CDE terminology/ DCE terminology
Fischer-race
Superscripts (Rh^1) refers to
Genes
Subscripts (Rh1)refer to
Agglutinogen
Also known as alphanumeric nomenclature
Rosenfield nomenclature
it is simpler as it only explains the presence or absence of a given antigen
Rosenfield
Attempts to standardize nomenclature
● Six digit numbers are assigned to each blood group specificity
● 004 refers to the Rh system
ISBT
has no genetic basis.
ISBT
located on chromosome 1
RH
the antigen closely associated phenotypically with Rh; it is formerly known as Rh25
LW
the result of the reaction between the red cells and antisera (anti-D, anti-C, anti-c, anti-E, anti-e).
Phenotype
the genetic makeup and can be predicted using the phenotype and by considering the race of an individual.
Genotype
Anti-D, anti-C, anti-E, anti-c, and anti-e is tested with
Px RBCs
combination of dominant and recessive
Heterozygous
either 2 dominant or 2 recessive genes are combined
Homozygous
IgG, react optimally at 37o C
Rh Antibodies
Produced after exposure of the individual’s immune system to foreign red cells, either through transfusion or pregnancy.
Rh Antibodies
are highly immunogenic, the D antigen is most potent
Rh Antigens
Arrange Rh antigens according to its immunogenicity (high-low)
D>c>E>C>e
- react strongly with specific Rho ags in saline medium & react less strongly in a protein
medium - Bivalent or complete antibodies
First order of Rh abs
Second order
- visibly with specific ag in a protein medium
In saline, weakly combine with the ag
Rh abs but do not produce a visible reaction - Albumin-reacting antibodies, incomplete, or
monovalent
- react visibly with specific ags in the antiglobulin medium only
- Most typical Rh antibodies, anti-human globulin (AHG) antibodies
Third order of Rh Abs
essential when testing donor blood sample.
D status
If any donor blood sample that types Rho(D) negative by either slide or rapid method must be tested further by
IAT
When Rh-positive red cell samples are typed for _________. It is expected that they will react strongly with anti-D reagent.
Weak D (Du Ag)
Red cells carrying the weaker D Ag have been referred to as having the
Du type
→ Inheritance of D genes that code for a weakened expression of the D Ag
→ The D Ag expressed appear to be complete but few in number.
Genetic weak D
→ This interference with D expression does not occur
when the C gene is inherited in the cis
C trans
If the position of C and D is trans
(opposite haplotype) = weak D expression
If the position of C and D is cis
(same haplotype) = no weak D expression
→ One or more parts of the D Ag are missing or altered
Partial D or D Mosaic
If the patient is transfused with D positive red cells, they may develop an
anti-D alloantibody
a phenotype occurring in individuals whose red blood cells possess an extremely low number of D antigen sites that most reagent anti-D are unable to detect.
D el
results from a hybrid gene RHCE-RHD-RHCE where
only a small portion of RHD is inserted into the RHCE gene.
R0HAR / DHAR
found in individuals of African descent; results from a specific amino acid change in the Rhce gene
ceCF (Crawford)
are produced by the same Rh gene complexes that produce C and D antigens.
G antigens
Individuals who lack Rh ags on the rbc
Rh null
partial suppression of RH gene expression caused by mutations in the RHAG gene
Rh mod
● No Cc and/or Ee reactivity
● Have unusually strong D expression (exalted D)
● Indicated by dash (-)
DELETIONS
● Control cellular used when AHG test is negative
● To confirm that washing has been adequate and the antiglobulin reagent is reactive
Coomb’s cells
False Positive Reactions may be caused by:
- positive DAT
-rouleax formation
Cold Auto agglutinis
False Negative Reactions may be caused by:
-incorrect cell suspension
- Improper procedure
antigen excess
Postzone effect
antibody excess
Prozone effect
