Unit 6: Rh Blood Group System

Who discovered anti-D in a postpartum woman?

Levine & Stetson (1939)

Who injected monkey RBCs and found Rh reactivity?

Landsteiner & Weiner (1940)

What was the conclusion about the two antibodies?

Same antibody → named anti-D

What are the 5 major Rh antigens?

D, C, c, E, e

Which Rh antigen has no true antithetical allele?

D

What is the "d antigen"?

Absence of D (amorphic allele)

D antigen frequency: White / Black

85% / 92%

C antigen frequency: White / Black

68% / 27%

c antigen frequency: White / Black

80% / 96%

E antigen frequency: White / Black

29% / 22%

e antigen frequency: White / Black

98% / 98%

What genes are inherited in Fisher-Race theory?

D/d, C/c, E/e (as haplotypes)

Fisher-Race: DCe/dce expresses what antigens?A: D, C, c, e

D, C, c, e

Fisher-Race: dce/dce expresses what antigens?

c, e (D−)

What does the Weiner theory say?

1 gene → 1 agglutinogen (e.g., R¹ = DCe)

Why is Weiner theory outdated?

Now replaced by 2-loci model

Fisher-Race: Dce = ? (Weiner)

R⁰

Fisher-Race: DCe = ?

R¹

Fisher-Race: dce = ?

r

Weiner: R² = ? (Fisher-Race)

DcE

What is the RH code for D antigen?

RH:1

RH code for C, E, c, e?

C = RH:2, E = RH:3, c = RH:4, e = RH:5

What does Rh:1,2,-3,4,5 mean?

Positive for D, C, c, e; Negative for E

ISBT system for Rh BGS?

004 (D = 004001, c = 004004)

What is phenotyping?

Serologic testing for RBC antigens

What does phenotype ≠ genotype mean?

Due to zygosity or gene silencing

Why do we care about Rh antigen frequencies?

Helps find compatible blood in antibody patients

Why is D the most important after ABO?

Highly immunogenic; causes HDFN & HTR

What is weak D?

Decreased D antigen expression

Genetic weak D (quantitative): make anti-D?

No

Position effect weak D (D trans to C): anti-D?

No

Partial D (missing epitopes): anti-D?

Yes

Transfuse weak D RBCs into D− patient: safe?

Only if NOT partial D

Weak D test steps?

Incubate with Anti-D → wash → AHG → agglutination = +

What type of test is the weak D test?

Indirect antiglobulin test (IAT)

AB+ with Anti-D and Rh Control both positive → valid?

No → Rh Control should be negative

ABO antibodies: natural or immune?

Naturally occurring (IgM)

Rh antibodies: natural or immune?

Immune (IgG)

ABO reaction type?

Immediate HTR, HDFN

Rh reaction type?

Delayed HTR, HDFN

Rh antibodies: class and temp?

IgG; react at 37°C and AHG

Can Rh antibodies cause HDFN?

Yes

Which Rh antibody is often warm autoantibody?

Anti-e

What cells have G antigen?

All D+ and all C+ cells

Why is anti-G confusing?

Mimics anti-D + anti-C

How to manage anti-G in pregnancy?

If anti-D is ruled out, still give RhIg

Rhnull phenotype?

No D, C, c, E, e antigens

Rhnull antibody?

Anti-Rh29 (total anti-Rh)

-D- or D-- phenotype?

Only D antigen present

Associated antibody in -D-?

Anti-Rh17

Cw antigen: frequency?

~2% (low)

Cw antibody: significance?

IgG, can cause HDFN/HTR

f antigen appears when?

c and e in cis

rhi antigen appears when?

C and e in cis

V and VS: common in which population?

Black population (30-40%)

Why phenotype SCD patients?

Reduce alloimmunization from frequent transfusions

Which antigens are matched in SCD transfusion?

C, c, E, e, K

Most common D+ genotype?

R¹r (DCe/dce)

Most common D− genotype?

rr (dce/dce)

Formula for # of units to screen?

Units = # needed / % compatible

Preanalytical Rh typing errors?

Mislabeling, wrong patient draw

Analytical Rh typing errors?

Reagent or technique error

Postanalytical Rh typing errors?

Reporting/transcription error

What do all Rh testing errors risk?

Inappropriate transfusion