RH BLOOD GROUP SYSTEM Flashcards
What do the terms “Rh-positive” and “Rh-negative” refer to?
These terms refer to the presence or absence of the D antigen on red blood cells.
What are the more accurate terms for “Rh-positive” and “Rh-negative”?
The more accurate terms are “D-positive” and “D-negative.”
What would you expect in individuals typed as “A, D-negative”?
Individuals typed as “A, D-negative” would be expected to have anti-B antibodies in their serum but not anti-D.
How does the absence of D or other Rh antigens on red cells differ from the ABO system?
Unlike the ABO system, the absence of D or other Rh antigens on red cells does not necessarily correspond with the presence of the antibody in the plasma.
What is required for the production of anti-D and other Rh blood group system antibodies?
The production of these antibodies requires immune red cell stimulation from red cells positive for the antigen.
Note: This exposure can occur during transfusion or pregnancy.
When was the discovery of the Rh blood group system made, and what led to it?
The discovery followed investigations into adverse transfusion reactions and hemolytic disease of the fetus and newborn (HDFN).
In 1940, Levine and Stetson linked HDFN to the Rh blood group system.
Why was it named the “Rh” blood group system?
The name “Rh” originated from the similarity of the Rh antibody to one produced by stimulating guinea pigs and rabbits with rhesus monkey cells.
The rhesus antibody specificity was actually directed toward another red cell antigen, which was named LW in honor of Landsteiner and Wiener.
Which genes encode the Rh blood group system antigens, and where are they located?
The Rh blood group system antigens are encoded by two closely linked genes: RHD and RHCE. These genes are located on chromosome 1
What is the current theory explaining genetic control of Rh antigen expression?
The current theory involves characterizing the amino acid sequences produced by genes that code for proteins on the red cell membrane.
What does the RHD gene determine in terms of antigen expression?
The RHD gene determines the expression of the D antigen on the surface of red blood cells.
What happens in D-negative individuals?
D-negative individuals have no genetic material at the RHD site.
Is there an antithetical “d” antigen?
No, an antithetical “d” antigen does not exist. However, the small “d” notation is sometimes used to indicate a D-negative gene.
What does the adjacent RHCE gene determine?
Answer: The RHCE gene determines the specificities of other Rh antigens, including C, c, E, and e
What variations occur at the RHCE locus, and what do they encode?
The alleles at the RHCE locus are RHCE, RHCe, RHcE, and RHce. They encode CE, Ce, cE, and ce, respectively.
disadvantages of not having Rh antigens on the surface of rbc
The lack of Rh blood group system antigens, called Rhnull, causes a membrane abnormality that shortens red cell survival.
What did Fisher and Race propose about the inheritance of Rh blood group system antigens?
Fisher and Race postulated that the Rh blood group system antigens were inherited as a gene complex or haplotype that codes for three closely linked sets of alleles.
Specifically, they suggested that the D gene is inherited at one locus, the C or c genes at the second locus, and the E or e genes at the third locus
How does each parent contribute to the Rh genes in their offspring?
Each parent contributes one haplotype or set of Rh genes to their offspring. These genes determine the expression of Rh antigens on red blood cells.
Why is the term “d” sometimes used in Rh terminology?
The term “d” (little d) is used to indicate the lack of the D antigen (i.e., Rh negative). However, there is no actual “little d” antigen; it’s a slang term to denote the absence of D.
