Rh Blood Group System
- It is imperative to have a basic understanding of Rh, as RhD typing is a critical component of
pretransfusion testing.
- In addition, clinically important Rh antibodies are relatively common in pregnancy and in patients
requiring blood transfusion.
Introduction
Rh
refers to a specific red blood cell antigen D
and to a complex blood group system currently composed of over 50 antigenic specificities.
Second most important blood group system in terms of transfusion. Rh antigens are very
immunogenic
Rh antibodies are produced only after exposure to foreign red blood cells.
Once present, they can produce:
1. HDFN: Hemolytic disease of the fetus or the new born- also known as Erythroblastosis fetalis
2. HTR: Hemolytic Transfusion Reaction
Rh positive- individual’s red blood cells possess one particular Rh antigen, the D antigen.
Rh negative- red blood cells lack the D antigen.
The terms Rh-positive or positive and Rh-negative or negative are routinely used by the public
and by experts in the field when referring to blood type—for example, A-positive or A-negative.
History
Levine and Stetson described a hemolytic transfusion reaction in an obstetrical patient after delivering
a stillborn needed transfusion. Same blood type with the husband. She later on exhibited signs of acute
HTR.
An antibody was isolated from the mother’s serum that reacted both at 37 degrees Celsius and 20
degrees Celsius with the father’s RBC’s.
It was postulated that the father possessed a common factor the mother lacked.
Terminology: used to describe Rh-derived from 4 sets of investigators
1. Fisher-Race: DCE Terminology
▪ Based on postulated genetic mechanisms of the Rh system
2. Wiener: Rh-Hr Terminology
▪ Based on postulated genetic mechanisms of the Rh system
3. Rosenfield and Coworkers: Alphanumeric Terminology
▪ Presence or absence of a given antigen
4. ISBT: Updated Numeric Terminology
▪ combined efforts of the ISBT(international Society of blood transfusion) Working
Party on the terminology for red cell surface antigens
Fisher-Race: DCE Terminology
• They postulated that the antigens of the system were produced by 3 closely linked set of
alleles.
• They named the antigens of the system D, d, C, c, E, e.
• “d”- absence of the D antigen.
• In the 1940s, Fisher and Race8 were investigating antigens found on human RBCs, including the
newly defined Rh antigen.
• Each gene is responsible for producing a product on the RBC membrane
• Fisher-Race theory
Each person inherits a set of Rh genes from each parent
• Rh genes are codominant- each inherited gene expresses its corresponding antigen on the RBC.
• i.e., one D or d, one C or c, and one E or e)
• The combination of maternal and paternal haplotypes determines one’s genotype (the Rh genes
inherited from each parent) and dictates one’s phenotype.
• An individual’s Rh phenotype is reported as DCE rather than CDE because Fisher postulated
that the C/c locus lies between the D/d and E/e loci.
, - Because Rh genes were thought to be codominant, each inherited gene expresses its corresponding
antigen on the RBC.
- They postulated that the antigens of the system were produced by three closely linked sets of alleles
(Fig. 7–1).
- Each gene was responsible for producing a product (or antigen) on the RBC surface.
• The combination of maternal and paternal haplotypes determines one’s genotype and dictates one’s
phenotype.
• Probable genotype of a person exhibiting deletion phenotype: DC- or Dc- or D-
• Absence of Rh antigens on the RBC: Rhnull
• Weakened expression of all Rh antigens : Rhmod phenotype
• In very rare instances, an individual may fail to express any allelic antigen at one or both Rh loci; that
is, a person may lack E and e, or all CcEe antigens.
• Rhnull phenotype: ---/---
• Rhmod: placing a parenthesis around (D), (C), and (e) indicates weakened expression
Wiener: Rh-Hr Terminology
Wiener believed that there was one gene responsible for defining Rh that produced an agglutinogen
containing a series of blood factors.
This Rh gene produced at least 3 factors within an agglutinogen.
Agglutinogen: phenotypic expression of the haplotype
Each factor is an antigen recognized by an antibody. Antibodies can recognize single
or multiple factors (antigens).
- According to Weiner, this Rh gene produced at least three factors within an agglutinogen
- The agglutinogen may be considered the phenotypic expression of the haplotype.
- Each factor is an antigen recognized by an antibody. Antibodies can recognize single or multiple factors
(antigens).
- When describing an agglutinogen:
o R- presence of D antigen
o r- absence of D antigen
o C- 1 or single prime (’)
o c- no 1 or single prime (’)
- It is imperative to have a basic understanding of Rh, as RhD typing is a critical component of
pretransfusion testing.
- In addition, clinically important Rh antibodies are relatively common in pregnancy and in patients
requiring blood transfusion.
Introduction
Rh
refers to a specific red blood cell antigen D
and to a complex blood group system currently composed of over 50 antigenic specificities.
Second most important blood group system in terms of transfusion. Rh antigens are very
immunogenic
Rh antibodies are produced only after exposure to foreign red blood cells.
Once present, they can produce:
1. HDFN: Hemolytic disease of the fetus or the new born- also known as Erythroblastosis fetalis
2. HTR: Hemolytic Transfusion Reaction
Rh positive- individual’s red blood cells possess one particular Rh antigen, the D antigen.
Rh negative- red blood cells lack the D antigen.
The terms Rh-positive or positive and Rh-negative or negative are routinely used by the public
and by experts in the field when referring to blood type—for example, A-positive or A-negative.
History
Levine and Stetson described a hemolytic transfusion reaction in an obstetrical patient after delivering
a stillborn needed transfusion. Same blood type with the husband. She later on exhibited signs of acute
HTR.
An antibody was isolated from the mother’s serum that reacted both at 37 degrees Celsius and 20
degrees Celsius with the father’s RBC’s.
It was postulated that the father possessed a common factor the mother lacked.
Terminology: used to describe Rh-derived from 4 sets of investigators
1. Fisher-Race: DCE Terminology
▪ Based on postulated genetic mechanisms of the Rh system
2. Wiener: Rh-Hr Terminology
▪ Based on postulated genetic mechanisms of the Rh system
3. Rosenfield and Coworkers: Alphanumeric Terminology
▪ Presence or absence of a given antigen
4. ISBT: Updated Numeric Terminology
▪ combined efforts of the ISBT(international Society of blood transfusion) Working
Party on the terminology for red cell surface antigens
Fisher-Race: DCE Terminology
• They postulated that the antigens of the system were produced by 3 closely linked set of
alleles.
• They named the antigens of the system D, d, C, c, E, e.
• “d”- absence of the D antigen.
• In the 1940s, Fisher and Race8 were investigating antigens found on human RBCs, including the
newly defined Rh antigen.
• Each gene is responsible for producing a product on the RBC membrane
• Fisher-Race theory
Each person inherits a set of Rh genes from each parent
• Rh genes are codominant- each inherited gene expresses its corresponding antigen on the RBC.
• i.e., one D or d, one C or c, and one E or e)
• The combination of maternal and paternal haplotypes determines one’s genotype (the Rh genes
inherited from each parent) and dictates one’s phenotype.
• An individual’s Rh phenotype is reported as DCE rather than CDE because Fisher postulated
that the C/c locus lies between the D/d and E/e loci.
, - Because Rh genes were thought to be codominant, each inherited gene expresses its corresponding
antigen on the RBC.
- They postulated that the antigens of the system were produced by three closely linked sets of alleles
(Fig. 7–1).
- Each gene was responsible for producing a product (or antigen) on the RBC surface.
• The combination of maternal and paternal haplotypes determines one’s genotype and dictates one’s
phenotype.
• Probable genotype of a person exhibiting deletion phenotype: DC- or Dc- or D-
• Absence of Rh antigens on the RBC: Rhnull
• Weakened expression of all Rh antigens : Rhmod phenotype
• In very rare instances, an individual may fail to express any allelic antigen at one or both Rh loci; that
is, a person may lack E and e, or all CcEe antigens.
• Rhnull phenotype: ---/---
• Rhmod: placing a parenthesis around (D), (C), and (e) indicates weakened expression
Wiener: Rh-Hr Terminology
Wiener believed that there was one gene responsible for defining Rh that produced an agglutinogen
containing a series of blood factors.
This Rh gene produced at least 3 factors within an agglutinogen.
Agglutinogen: phenotypic expression of the haplotype
Each factor is an antigen recognized by an antibody. Antibodies can recognize single
or multiple factors (antigens).
- According to Weiner, this Rh gene produced at least three factors within an agglutinogen
- The agglutinogen may be considered the phenotypic expression of the haplotype.
- Each factor is an antigen recognized by an antibody. Antibodies can recognize single or multiple factors
(antigens).
- When describing an agglutinogen:
o R- presence of D antigen
o r- absence of D antigen
o C- 1 or single prime (’)
o c- no 1 or single prime (’)
