ABO Blood Group System and Immunohematology Review

This set covers chromosomal locations, ISBT terminology, historical milestones, biochemistry of ABH antigens, secretor status, subgroups, and the resolution of ABO discrepancies based on the Immunohematology Week 5 lecture.

According to the transcript, which chromosome is the locus for the ABO blood group system?

$$9$$

What are the six-digit ISBT numeral codes composed of?

The first three digits are designated for the blood group system, and the remaining three digits are for antigenic specificity.

In what year and by whom was the blood type AB (the 4th blood type) discovered?

In $1902$ by Von Decastello & Adriano Sturli

What is the immunodominant sugar associated with the A antigen?

N-acetyl-D-galactosamine

Which enzyme codes for the production of the H antigen?

$$\text{Alpha-2-L-fucosyltransferase}$$

What is the primary difference in the chemical linkage between Type 1 and Type 2 precursor chains?

Type 1 precursor chain has a $\beta 1-3$ linkage, while Type 2 precursor chain has a $\beta 1-4$ linkage.

Why is reverse typing considered invalid for newborn infants?

The antibodies found in the infant's sample are of maternal origin ($\text{IgG}$ maternal antibodies) and not produced by the infant.

Which specific lectin is used as the reagent to differentiate between A1 and A2 subgroups?

Dolichos biflorus

What is the genotype of the Bombay phenotype and why does it lack ABH antigens?

The genotype is $hh$ (or H null); it lacks expression because the absence of the H gene means L-fucose is not added to the type 2 chain.

In the context of ABO discrepancies, what defines a Group I discrepancy?

An unexpected reaction in the reverse grouping, often due to weakly reacting or missing antibodies.

Which bacteria are associated with causing the Acquired B phenomenon?

E.coli O86, Clostridium tertium, and Proteus vulgaris OX-19

What is the recommended resolution for a Group III discrepancy caused by Rouleaux formation?

Perform saline dilution or the saline replacement technique.

What is the immunodominant sugar for the B antigen?

D-galactose

According to Bernstein's 1924 description, how is the ABO blood group inherited?

An individual inherits one ABO gene from each parent following simple Mendelian genetics.

What is used as the indicator cells and the specimen in the detection of secretor status?

The specimen is saliva and the indicator cells are Red Blood Cells.

What are the common causes of Group II discrepancies, which involve unexpected reactions in forward typing?

Subgroups of A and B, leukemias, Hodgkin’s disease, Acquired B phenomenon, and excess blood group specific soluble substances (BGSS).

What reagent is used to disperse IgM related agglutination in Group IV discrepancies if other methods fail?

$0.01\text{M}$ dithiothreitol

Which blood group phenotype shows the greatest reactivity with Anti-H lectin (Ulex europaeus)?

Blood group O