Rh Blood Group System

What is the most common Rh phenotype in black people?

Dce

What is the most common Rh phenotype in white people?

DCe

What is the role of the RhAG gene?

Required for expression of Rh proteins (RhD and RhCE)

Not a part of the Rh Blood group system, but provides the “instructions” for making proteins required for the production of Rh antigens

What chromosome is the RhAG gene coded on?

6

What is the Fisher-Race theory?

That the Rh system was inherited as a haplotype.

One gene was for D antigen

One gene was for C or c antigen

One gene was for E or e antigen

What is the Wiener theory?

That one loci was responsible for Rh system expression

What is immunogenicity?

The ability of an antigen to elicit an immune response

What is the order of Rh immunogenicity?

D > c > E > C > e

What % of D-Negative patients exposed to D will develop anto-D?

85%

What is Weak D (D^u)

D phenotype, where D antigen expression on RBC is reduced, and the antigen may not be detectable by routine techniques

labled as D positive

What is clinically significant about Partial D/Mosaic D?

persons are missing part of D-antigen complex

Can produce anti-D if exposed to whole D-antigen

C /c differ by a single AA difference at position ___ ?

103

E/e differ by a single AA difference at position ___?

226

C/c and E/e are _____ alleles?

Co-dominant

What is the clinical significance of the G antigen?

Patients can produce an Anti-G that mimics an Anti-C and Anti-D

How is the G antigen made?

Produced by the presence of a C and/or D antigen due to the presence of a serine residue at that position

When is the f antigen expressed?

When both c and e antigens are present on the red blood cell and the respective genes are in the cis position or on the same chromosome

What is the clinical significance of the f antigen?

Anti-f can cause transfusion reactions and HDFN.

In regards to the f antigen, RBCs of the Dce/dCE genotype will be f ____? (pos or neg)

Postive

In regards to the f antigen, RBCs of the DcE/dCe genotype will be f ____? (pos or neg)

negative

What are compound antigens? What are examples?

An additional antigen product when two genes are inherited in cis position (together on the same gene)

ex.

f antigen (formed when c and e are in the cis positions)

Ce antigen (formed when C and e are in the cis positions)

Describe Partial deletion?

Patient is negative for C/c and/or E/e antigens and may or may not have D antigen activity

D- -, DC-, D-e, etc

Describe Rh Null

No Rh antigen sites on RBCs leading to

• Stomatocytosis

• Hemolytic anemia

Genotype written ---/---

What are the two types of Rh null?

Regulator: gene is inherited, but not expressed

Amorph: RHD gene is absent, no expression of RHCE gene

Describe Rh mod?

Depression of Rh antigen with characteristics similar to Rhnull, but less severe.

What is dosage?

A significant difference in antibody reaction strength depending on the quantity of the target antigen present on a target red blood cell.

Which Rh antigens can dosage be seen in?

Dosage reactions can be seen with C/c and E/e

What enhancement can improve Rh antibody reactivity?

Albumin

LISS

Proteolytic Enzymes

PEG

What does High Protein D Typing Reagent consist of and what does it do?

IgG anti-D in 20% protein dilution

The high protein environment helps produce agglutination at immediate spin

*A Rh Control is required for this reagent

What does Low Protein Reagent consist of, and what does it do?

Monoclonal or polyclonal IgM anti-D in 6% protein solution

The IgM form of the antibody allows agglutination to occur at immediate spin without the need for high albumin content

What is chemically modified anti-D?

Chemically alter anti-D to allow it to agglutinate directly without protein media