Immunohematology: Rh and Other Blood Group Systems

Flashcards covering the history, nomenclature, genetics, and clinical significance of Rh, Kell, Duffy, Kidd, Lewis, and other uncommon blood group systems as discussed in the lecture notes.

Levine and Stetson (1940)

The researchers who first linked Hemolytic Disease of the Fetus and Newborn (HDFN) to the Rh Blood Group System.

RHAG gene

A coexpressor gene located on Chromosome 6 responsible for the production of RHAG glycoprotein; its absence can cause the Rh null phenotype.

Stomatocytosis

The specific RBC morphology abnormality expected in individuals with the Rh null phenotype due to the lack of Rh glycoprotein.

Serine at position 103

The specific amino acid on the RHCE protein responsible for the expression of the capital C antigen.

Proline at position 103

The specific amino acid on the RHCE protein responsible for the expression of the small c antigen.

Fisher-Race Theory

The genetic theory that proposes three different genes (D, C/c, E/e) on three different loci in close proximity on Chromosome 1.

Weiner Theory

The genetic theory that proposes one single gene codes for three antigenic combinations ($R^0, R^1, R^2, R^Z, r, r', r'', r^y$).

Rosenfield Numeric Technology

A nomenclature system that assigns numbers to antigens (Rh1:D, Rh2:C, Rh3:E, Rh4:c, Rh5:e) and uses leading minus signs for negative results.

Rh Antigen Immunogenicity

The ranking of Rh antigens by their ability to stimulate antibodies: $D > c > E > C > e$.

Partial D (D Mosaic)

A variation where one or more epitopes of the D antigen are missing; these individuals are considered D positive but can make Anti-D to the missing parts.

C-trans position effect

A mechanism of weakened D expression occurring when the $RhD$ gene is on one chromosome and $RhCe$ is on the opposite chromosome.

Kell (006) & Kx (019)

Linked blood group systems where Kell antigens are carried on a glycoprotein connected by disulfide bonds to the Kx membrane protein.

Sulfhydryl reagents

Chemicals such as $2$-mercaptoethanol ($2$-ME), Dithiothreitol (DTT), and AET that destroy Kell antigens by breaking disulfide bonds.

McLeod Syndrome

A condition characterized by the absence of Kx and Km antigens, resulting in acanthocytic RBC morphology and associated with Chronic Granulomatous Disease (CGD).

Duffy (008) Silent Allele ($Fy$)

An allele common in African populations that results in the $Fy(a-b-)$ phenotype, providing resistance to Plasmodium vivax malaria.

Kidd (009) Notorious Reputation

Kidd antibodies (Anti-$Jk^a$, Anti-$Jk^b$) are known for declining rapidly in titer, frequently causing delayed Hemolytic Transfusion Reactions (HTR).

Dombrock (014)

A blood group system residing on Chromosome 12 characterized by antibodies that share a similar reputation to Kidd antibodies (quick disappearance and delayed HTR).

Diego (010)

A system where antigens reside on Band 3 (AE1); the $Di^a$ antigen is a notable marker for Mongolian ancestry.

Colton (015)

A system where antigens are carried on Aquaporin 1, an integral protein responsible for $80\%$ of water reabsorbed in the kidneys.

Chido/Rodgers (017)

A system with antigens adsorbed from plasma onto the RBC membrane; they reside on the $C4$ complement protein and are clinically insignificant.

Lewis (007) System

The only blood group system where antigens are not manufactured by the RBC; they are secreted as glycoproteins into saliva and adsorbed as glycolipids from plasma.

P1 antigen

An antigen poorly expressed at birth whose strength decreases upon storage; it can be neutralized by Hydatid cyst fluid from Echinococcus granulosus.

Donath-Landsteiner Antibody

An autoanti-P IgG antibody associated with Paroxysmal Cold Hemoglobinuria (PCH) that binds complement in the cold and causes lysis in the warm.

Pathologic Autoanti-I

An IgM autoantibody produced after Mycoplasma pneumoniae infection that causes Cold Agglutinin Disease (CAD) and acrocyanosis.

Glycophorin A (GPA)

The RBC membrane structure that carries the M and N antigens, which are easily destroyed by enzymes like ficin and papain.

U (Universal) antigen

A high-incidence antigen in the MNSs system; individuals who are $S-s-$ are typically U-negative, a phenotype found only in the Black population.

MIRL (Membrane inhibitor of lysis)

The gene product of CD59 (ISBT 035) that protects RBCs from complement lysis by inhibiting the binding of $C8$ and $C9$.

JMH (026) aging effect

A unique characteristic where the number of JMH antigens on RBCs declines as an individual reaches $50$ years of age or older.