Session 3 - Reasons behind RhD Myth & Mystery
-
Upload
qbd18940 -
Category
Health & Medicine
-
view
2.142 -
download
2
Transcript of Session 3 - Reasons behind RhD Myth & Mystery
![Page 1: Session 3 - Reasons behind RhD Myth & Mystery](https://reader033.fdocuments.in/reader033/viewer/2022052901/556ba5b3d8b42a207e8b4a19/html5/thumbnails/1.jpg)
The myth and mystery of RhD
Joyce Poole
International Blood Group Reference Laboratory Bristol UK
Quotient Biodiagnostics Industry Workshop AABB San Diego 2011
![Page 2: Session 3 - Reasons behind RhD Myth & Mystery](https://reader033.fdocuments.in/reader033/viewer/2022052901/556ba5b3d8b42a207e8b4a19/html5/thumbnails/2.jpg)
• Reasons why myth and mystery surround RhD!
• Case studies with learning points: pregnancy, transfusion, donor-related
• IBGRL approaches and use of ALBAclone anti-D panel
• UK typing protocols for D typing and treating D variant patients
Objectives of my talk
![Page 3: Session 3 - Reasons behind RhD Myth & Mystery](https://reader033.fdocuments.in/reader033/viewer/2022052901/556ba5b3d8b42a207e8b4a19/html5/thumbnails/3.jpg)
• Secret or hidden
• Puzzling
Mystery?
![Page 4: Session 3 - Reasons behind RhD Myth & Mystery](https://reader033.fdocuments.in/reader033/viewer/2022052901/556ba5b3d8b42a207e8b4a19/html5/thumbnails/4.jpg)
Why is D difficult
•Not a simple antigen
•Nomenclature is confusing
• D typing is not straightforward
• Controversial
The mystery of RhD
Complex
Clinically significant!
![Page 5: Session 3 - Reasons behind RhD Myth & Mystery](https://reader033.fdocuments.in/reader033/viewer/2022052901/556ba5b3d8b42a207e8b4a19/html5/thumbnails/5.jpg)
•Huge molecular diversity
• >150 variant D antigens
• >50 ways of being D negative/Del
The mystery of RhD
![Page 6: Session 3 - Reasons behind RhD Myth & Mystery](https://reader033.fdocuments.in/reader033/viewer/2022052901/556ba5b3d8b42a207e8b4a19/html5/thumbnails/6.jpg)
Complexity
• Not derived from an amino acid polymorphism but from presence of RhD protein
• D expression dependent on different epitopes along the RhD protein
• Epitopes are conformation-dependent
• Antigen expression varies quantitatively and qualitatively
The mystery of RhD
![Page 7: Session 3 - Reasons behind RhD Myth & Mystery](https://reader033.fdocuments.in/reader033/viewer/2022052901/556ba5b3d8b42a207e8b4a19/html5/thumbnails/7.jpg)
Confusing Nomenclature
•D+
•D-
D category D mosaic
Partial D Weak D
Weak partial D D variant
The mystery of RhD
![Page 8: Session 3 - Reasons behind RhD Myth & Mystery](https://reader033.fdocuments.in/reader033/viewer/2022052901/556ba5b3d8b42a207e8b4a19/html5/thumbnails/8.jpg)
Controversial
D+ or D- ?
The mystery of RhD
Do we treat the patient as D+ or D-?
![Page 9: Session 3 - Reasons behind RhD Myth & Mystery](https://reader033.fdocuments.in/reader033/viewer/2022052901/556ba5b3d8b42a207e8b4a19/html5/thumbnails/9.jpg)
The myth of RhD
Widely held but false notion
D typing is routine test and should therefore be straightforward!
![Page 10: Session 3 - Reasons behind RhD Myth & Mystery](https://reader033.fdocuments.in/reader033/viewer/2022052901/556ba5b3d8b42a207e8b4a19/html5/thumbnails/10.jpg)
D typing
How do we do it ?
Column
![Page 11: Session 3 - Reasons behind RhD Myth & Mystery](https://reader033.fdocuments.in/reader033/viewer/2022052901/556ba5b3d8b42a207e8b4a19/html5/thumbnails/11.jpg)
Like this balancing act, D typing can be difficult
for the majority of us
![Page 12: Session 3 - Reasons behind RhD Myth & Mystery](https://reader033.fdocuments.in/reader033/viewer/2022052901/556ba5b3d8b42a207e8b4a19/html5/thumbnails/12.jpg)
GUIDELINES
Compatibility procedures in blood transfusion laboratories
BCSH British Committee for Standards in Haematology/
Blood Transfusion
(Transfusion Medicine 2004:14:59-73)
Patients
![Page 13: Session 3 - Reasons behind RhD Myth & Mystery](https://reader033.fdocuments.in/reader033/viewer/2022052901/556ba5b3d8b42a207e8b4a19/html5/thumbnails/13.jpg)
• Test in duplicate with IgM monoclonal anti-D
• [Two anti-D or same one twice]
• Exception for full automation - single anti-D
• Anti-D should not detect DVI
D typing patients (1)
UK GUIDELINES
![Page 14: Session 3 - Reasons behind RhD Myth & Mystery](https://reader033.fdocuments.in/reader033/viewer/2022052901/556ba5b3d8b42a207e8b4a19/html5/thumbnails/14.jpg)
• The IAT should not be used
• Anti-CDE is of no value and is not recommended
[Misinterpretation of r’ and r’’ as D+]
UK GUIDELINES
D typing patients (2)
![Page 15: Session 3 - Reasons behind RhD Myth & Mystery](https://reader033.fdocuments.in/reader033/viewer/2022052901/556ba5b3d8b42a207e8b4a19/html5/thumbnails/15.jpg)
Non-compliance with guidelines!
• 24% not performing duplicate D typing are using
manual systems
• 5% using IAT anti-D for D neg pre-transfusion samples (3% in 2002) [recommended against]
• 6% include an anti-CDE reagent (10% 2002)
• 9 labs using one anti-D that detects DVI
• <1% diluting anti-D! (5% in 2002)
Data from UK NEQAS exercise late 2005
Patient D typing in UK
![Page 16: Session 3 - Reasons behind RhD Myth & Mystery](https://reader033.fdocuments.in/reader033/viewer/2022052901/556ba5b3d8b42a207e8b4a19/html5/thumbnails/16.jpg)
Donors
![Page 17: Session 3 - Reasons behind RhD Myth & Mystery](https://reader033.fdocuments.in/reader033/viewer/2022052901/556ba5b3d8b42a207e8b4a19/html5/thumbnails/17.jpg)
D typing donors
• Adopt procedures to maximise detection of weak D and partial D as D positive
• Determined on each donation
• D group in doubt?
Safer to classify as D+
![Page 18: Session 3 - Reasons behind RhD Myth & Mystery](https://reader033.fdocuments.in/reader033/viewer/2022052901/556ba5b3d8b42a207e8b4a19/html5/thumbnails/18.jpg)
Pregnant Woman (SR)
• Typed as normal D+ (Ro) but with allo anti-D in plasma
• All anti-D’s positive with her cells • No Ig anti-D given • Referred for RHD sequencing
Case Study
![Page 19: Session 3 - Reasons behind RhD Myth & Mystery](https://reader033.fdocuments.in/reader033/viewer/2022052901/556ba5b3d8b42a207e8b4a19/html5/thumbnails/19.jpg)
609 654 667 674 807
186 602 667 819
Novel DIII
RHD Psuedogene
609 654 667 674 807
RHD Psuedogene
Normal RHD
Twin son and daughter of SR - mutations in RHD
Patient SR - mutations in RHD
10 exons of RHD
10 exons of RHD
![Page 20: Session 3 - Reasons behind RhD Myth & Mystery](https://reader033.fdocuments.in/reader033/viewer/2022052901/556ba5b3d8b42a207e8b4a19/html5/thumbnails/20.jpg)
Transfusion Recipient
• Elderly male patient - normal D+ with allo anti-D
• Transfused in 1975 with 4 units of D+ • RHD sequence – exon 4 mutation G520A (V174M)
• Characteristic of weak D type 33 • Transfused D negative from now on
Case Study
![Page 21: Session 3 - Reasons behind RhD Myth & Mystery](https://reader033.fdocuments.in/reader033/viewer/2022052901/556ba5b3d8b42a207e8b4a19/html5/thumbnails/21.jpg)
Blood Donor • Female donor typed as D- (r’’r) • Transfused to a D- recipient who made anti-D!
• Referred to IBGRL for elucidation • Very weak expression of D • Rh genotype D+
Case Study
RHD sequence: No mutations in RHD (or CE or RHAG)
![Page 22: Session 3 - Reasons behind RhD Myth & Mystery](https://reader033.fdocuments.in/reader033/viewer/2022052901/556ba5b3d8b42a207e8b4a19/html5/thumbnails/22.jpg)
Learning points
• Partial D and weak D can both present as normal D
• Some variants will only be detected if they have made anti-D
• Weak D’s can make allo anti-D • Important to detect very weak expression of D on donor cells to prevent immunisation
Case Studies
![Page 23: Session 3 - Reasons behind RhD Myth & Mystery](https://reader033.fdocuments.in/reader033/viewer/2022052901/556ba5b3d8b42a207e8b4a19/html5/thumbnails/23.jpg)
IBGRL referrals
UK hospitals Overseas reference
labs
Blood Centre
IBGRL
We do not do routine patient or donor typing
![Page 24: Session 3 - Reasons behind RhD Myth & Mystery](https://reader033.fdocuments.in/reader033/viewer/2022052901/556ba5b3d8b42a207e8b4a19/html5/thumbnails/24.jpg)
Reasons for referral • Pregnant female - do we give antenatal immunoglobulin anti-D?
• Patient is D+ with anti-D - is it allo or auto?
• Is this a weak D or partial D?
• Do we treat as D+ or D-?
IBGRL referrals
![Page 25: Session 3 - Reasons behind RhD Myth & Mystery](https://reader033.fdocuments.in/reader033/viewer/2022052901/556ba5b3d8b42a207e8b4a19/html5/thumbnails/25.jpg)
• 4 routine anti-D reagents that detect weak D + most partial D between them (+ C, Cw, c, E, e)
• ALBAclone IgG anti-D panel (12)
Clear-cut pattern Not clear
IBGRL referrals
Report
Refer for molecular analysis (RHD sequence)
1
2
![Page 26: Session 3 - Reasons behind RhD Myth & Mystery](https://reader033.fdocuments.in/reader033/viewer/2022052901/556ba5b3d8b42a207e8b4a19/html5/thumbnails/26.jpg)
411 RhD referrals in 5 years • Variants that gave clear patterns of reactivity vs the ALBAclone panel – DHK/DAU-4 : 17 – DVII : 12 – DVI : 9 – DFR : 7 – DMH : 6 – DOL : 6 – DAU-5 : 12 – DAR-E : 6 – Plus many others of even lower incidence
![Page 27: Session 3 - Reasons behind RhD Myth & Mystery](https://reader033.fdocuments.in/reader033/viewer/2022052901/556ba5b3d8b42a207e8b4a19/html5/thumbnails/27.jpg)
• Variants that can give ambiguous patterns of reactivity vs the ALBAclone panel – Weak D type 1 : 74 – Weak D type 2 : 79 – Weak D type 4.2.2 (DAR) : 50
• Why the variation? – Different individuals express different amounts of the RhD protein
– C in trans (R1*r’ and R2*r’) weakens expression of RhD
High referral rate
![Page 28: Session 3 - Reasons behind RhD Myth & Mystery](https://reader033.fdocuments.in/reader033/viewer/2022052901/556ba5b3d8b42a207e8b4a19/html5/thumbnails/28.jpg)
The variants DAU-5 and DV type 1 gave an identical serological pattern
+ + + + +/- + - + + + + + - - - (+)/
-
+ + + - + + + + + + + + + + - -
(+)/- + + - - + - + - - + - - - - -
+ + + + + + - + + + + + + + - -
+ + + - - + - + + + + - - - - -
+ + + - + + + + + + + + + + - -
+ + + - + + + + + + + + + + - -
+ - + - + + + + + + + + + +/- - -
(+)/-
+ + - - - - + - - - - - - - -
+ + + + + + - - - - (+) - (+) + + -
+ + + + + + - + + + + + + - - -
+ + + + + - - + + - + + - - + -
Kit
ID
Wk
D
Ty
pe
1 &
2
DII
&
DN
U
D I
II
D I
V
D V
DC
S
D V
I
D V
II
DO
L
DF
R
DM
H
DA
R
DA
R-E
DH
K /
DA
U-4
DB
T
RO
Ha
r
A
B
C
D
E
F
G
H
I
J
K
L
A novel finding
![Page 29: Session 3 - Reasons behind RhD Myth & Mystery](https://reader033.fdocuments.in/reader033/viewer/2022052901/556ba5b3d8b42a207e8b4a19/html5/thumbnails/29.jpg)
Diagrammatic representation of RhD
Extracellular
Trans-
membrane
Intracellular
Phe223Val Glu233Gln
Thr379Met
DAU-5: Phe223Val Glu233Gln Thr379Met
DV type 1: Phe223Val Glu233Gln
![Page 30: Session 3 - Reasons behind RhD Myth & Mystery](https://reader033.fdocuments.in/reader033/viewer/2022052901/556ba5b3d8b42a207e8b4a19/html5/thumbnails/30.jpg)
RhD model
90° rotation
Thr379
Phe223 Glu233
Thr379
Phe223
Glu233
Extracellular
Intracellular
DAU-5: Phe223Val, Glu233Gln, Thr379Met
DV type 1: Phe223Val, Glu233Gln
D CE RhAG
![Page 31: Session 3 - Reasons behind RhD Myth & Mystery](https://reader033.fdocuments.in/reader033/viewer/2022052901/556ba5b3d8b42a207e8b4a19/html5/thumbnails/31.jpg)
Does the similarity in reaction
profile matter?
• The clinical care of a patient with a DAR-E or DV type 1 is same
• Clear cut positive and negative reactions indicate loss of epitopes (partial D)
• Anti-D production possible
• Treat as D-
• Identifying weak D 1, 2 and 3 is important……………
NO
![Page 32: Session 3 - Reasons behind RhD Myth & Mystery](https://reader033.fdocuments.in/reader033/viewer/2022052901/556ba5b3d8b42a207e8b4a19/html5/thumbnails/32.jpg)
Patients • Identified weak D types 1,2 and 3 treat as D+
• Weak D type 4 onwards treat as D-
• Partial D treat as D-
UK Blood Service Policy
![Page 33: Session 3 - Reasons behind RhD Myth & Mystery](https://reader033.fdocuments.in/reader033/viewer/2022052901/556ba5b3d8b42a207e8b4a19/html5/thumbnails/33.jpg)
Transfusion to D variants
D- D+
Ig anti-D
prophylaxis
No Ig anti-D
prophylaxis
Inadequate rr
blood supply
May be
immunised
to make anti-D Inappropriate
use
of Ig anti-D
RISK
Unlikely in weak D types 1,2 and 3
D- blood D+ blood
![Page 34: Session 3 - Reasons behind RhD Myth & Mystery](https://reader033.fdocuments.in/reader033/viewer/2022052901/556ba5b3d8b42a207e8b4a19/html5/thumbnails/34.jpg)