RH Flashcards
GENETIC BASIS FOR EXPRESSION
• Controlled by two closely linked genes,(2) located on chromosome___.
RHD and RHCE
1
The_____ gene determines the presence or absence of the D antigen
The____ gene determines the C, c, E, and e antigen expressions.
RHD
RHCE
RHD
Allele:___
Antigens:____ or ____
D
D-positive or D-negative
RHCE
Alleles: (4)
Antigens: (4)
RHCE, RHCe, RHcE, RHce
CE, Ce, cE, ce
______are non-glycosylated transmembrane proteins that integrate into the RBC membrane.
Rh proteins
play a role in maintaining the structural integrity of red blood cells
Rh protein
Rh protein
Other hypotheses: they may have a role in transporting (2)
ammonia and CO2
The____ gene is deleted or inactive in Rh-negative individuals, leading to the absence of the D antigen.
RHD gene
______ genes can lead to weak, partial, or altered Rh antigen expressions.
Mutations and hybrid
• Variations in D antigen expression, known as______ phenotypes, arise when red blood cells (RBCs) display a weakened expression of the D antigen.
weak D
weak D
This can result from inheriting genotypes that lead to____expression of RBC antigens
heterozygous
• ________ occurs when______, reducing D expression without altering its structure.
• _______results from RHD gene mutations leading to fewer D antigen sites, but all epitopes are present.
• _______results from missing D epitopes, which can trigger anti-D antibody formation upon exposure to Rh-positive blood.
Position effect weak D; C is inherited in trans to D
Genetic weak D
Partial D (mosaic)
Position or gene interaction effect
Cis:
Trans:
DCe/ce
Dce/Ce
The Rh antigen on the RBC is normal, but the steric arrangement of the C antigen in relationship to the D antigen appears to interfere with the expression of D antigen.
Position effect: c in trans to d
Occurs when the RHD gene codes for a weakened expression of the D antigen.
In this case, the D antigens are complete but fewer in number.
Quantitative: genetic weak D
• The D antigen is not complete because one or more epitopes are missing
Partial D
D Mosaic
• If an individual lacks one (or more) pieces, or epitopes, of the total D antigen, alloantibody can be made to the missing epitopes if exposed to RBCs that possess the complete D antigen.
Partial D
D mosaic
• Anti-D made by individuals expressing _____can cause hemolytic disease of the fetus and newborn (HDFN) or transfusion reactions, or both.
partial D
do not produce anti-D antibodies after exposure to Rh-positive blood.
Weak D
C in trans to D
• If someone lacks a specific epitope, their immune system can recognize it as foreign if exposed to Rh-positive blood.
• The body may then produce anti-D antibodies against the missing epitopes.
D mosaic
• Rh Typing Discrepancies:
Routine serologic testing may misclassify Weak D individuals as Rh-negative if only______ is performed.
The ________is required to detect Weak D status.
immediate spin testing
Indirect Antiglobulin Test (IAT)
Transfusion Compatibility:
→ Can safely receive Rh-positive blood as they do not form anti-D antibodies.
C in Trans to D, Genetic Weak D
→ May develop anti-D if exposed to Rh-positive blood, so they should be treated as Rh-negative and transfused with Rh-negative blood.
• Partial D or other Weak D types
Blood donors
_______individuals are considered Rh-positive donors, as their RBCs may still carry sufficient D antigen to stimulate alloimmunization in an Rh-negative recipient.
Weak D
