Rh blood groups

• follows order of loci genes DCE
• DCE genes are inherited and linked
• each gene produces Ag
• absence of D = d
• little c and little e means gene are present present

• 1 RHo gene codes for agglutinogen which encodes for Rh antigens
• Rh',rh"

• R = D
• 1 = C
• 2 = E

• r = d
• ' = C
• " = E
• Rz = DCE
• ry = dCE

• 6 digit number for each Ag specificity
• first 3 indicate 004 = Rh
• last 3 indicate Ag specifity = 004001 = D

• Ro = Dce = blacks
• R1 = DCe = whites
• R2 = DcE = 14% white, 9% black
• r = dce =38% white, 25% black

• cannot use anti sera on recently transfused individuals
• anti sera not available for some antigens
• fetal genotyping for D can be done on fetal DNA present in maternal plasma

• nonglycosylated proteins
• transmembrane proteins with loops exposed to surface of RBC
• transport CO2 or ammonia
• across plasma membrane
• integral part of RBC membrane
• Rh null people have mild hemolytic anemia

• only anti D required for routine testing
• other typing sera used for typing RBCs to resolve antibody problems or family studies use statistical probability to determine most probable genotype

• parental testing
• predicting hemolytic disease of newborn
• confirmation of Rh Ab specificity
• finding compatible blood for Rh Abs specificity.

• mix unknown RBCs with Rh antiserum (forward typing)
• take tubes through phases ( IS, 37C, AHG, CCC)
• use published frequencies

• Rh and RhAG form a complex
• maintain cell stability
• regulate cell volume
• transports ammonia

• Rh locus on chromosome 1
• 2 closely linked Rh genes RHD and RHCE carry Rh antigens
• alleles are autosomal codominant
• linked together as a haplotype (DCe/dce, R1r)

Rh haplotype locus

• ABH antigens on 1st loop, no Rh antigens
• on chromosome 6
• serves as a helper for expression of Rh antigens

• if RBC not immediately agglutinated by anti D must be tested for weak D
• 1. incubate cells with anti D at 37 C, will sensitize if present
• 2 wash x3 add AHG
• AHG will bind to anti D coating cells if present
• if negative, individual is D negative
• if positive individual is D positive

• genetic - inheriting D genes resulting in lowered densities of D Ags on RBC membranes
• C-trans position -D gene is in trans arrangement big D is trans to C (Dce/dCe)
• D mosaic/partial D - parts of D Ag is missing, may result in production of anti D

• Rh+ and will receive Rh+
• except mosaic which will receive Rh-

lowered

• Dw mothers do NOT receive RhoGAM
• D negative do not receive Dw
• Dw may receive D neg

cDe/cDe (C has limiting effect on expression)

• very rare
• may be Ee or Cc
• must be homzygous for deletion to be detected
• no reaction when RBCs are tested with anti serum
• requires transfusion of other D deletion red cells, bc these individuals may produce antibodies with specificities
• written as D - - or -D-

• will have NO Rh antigens on RBCs
• genotype written as ---/---
• can only give an Rh null to an Rh null

• stomatocytosis
• hemolytic anemia
• why? lack of antigens will disrupt structural integrity

• regulator type - Rh gene inherited, but not expressed due to mutation in RHAG gene
• amorph type - RHD gene is absent or no exxpression of RHCE gene, when RHAG is normal

weakened expression of all Rh Ag

• when two Rh genes are on the same chromosome, cis position
• f positive cells will only react with other f positive cells in cis position, not trans

• f antigens - c and e are in cis (dce/dce)
• rh1 or Ce antigen - when C and e are in cis (dCe/dce)

• encoded by the same gene for C or D
• present in cells with C or D
• anti G mimics anti C and anti D

• C & Cw usually seen together
• 2% whites, very rare in blacks
• anti Cw may be naturally occuring and shows dosage

• saline based: for low protein, long incubation times, cannot perform weak D testing
• protein based: faster, incs false positives, requires control. can be used for weak D
• chemically modified anti D: in low protein, few false positives, saline control performed. can be for weak D testing
• blends of mAbs: using hybridized myeloma cells. Specific for Ab cells can be used for weak D. standard technique used now

• have two tubes with Anti D (labeled D) and Rh control (labeled C)
• centrifuge and read
• if D pos: Rh positive
• if D neg: continue testing for weak D
• add adjuvant and incubate
• centrifuge
• was 3 to 4 times with saline
• add AHG
• centrigue
• if D pos in any phase and control is neg, RBCs are Rh+
• if D and control are neg = RBC are neg
• if control is positive = indeterminate

to get rid of fibrin or protein, or else they would neutralize the coombs reagent giving a false negative

• IgG
• react warm or with AHG
• does not bind to complement, RBC destruction by Rh Abs is extravascular

D > c > E > C > e