Learn: Blood Typing (Everything Else)

Which genes/systems interact to determine Glob-related phenotypes?

The P1PK and P systems interact; the lecture emphasizes that interplay between genes determines phenotype.

"What is the biochemical basis of the Glob blood group system"

"It is sugar-based, similar to the ABH system."

How many main Glob phenotypes are noted in the lecture?

Five main phenotypes.

"Which Glob antibody is described as naturally occurring variably reactive and usually IgM?"

Anti-P1.

How can anti-P1 be neutralized?

With P1 substance.

Which other Glob antibodies are listed besides anti-P1?

"Anti-P, anti-PP1Pk, and anti-Tja."

What is paroxysmal cold hemoglobinuria (PCH) associated with in the Glob section?

Auto-anti-P; the lecture also lists tertiary syphilis and secondary viral infections as associations.

What is the characteristic hemolysis pattern in PCH?

Biphasic hemolysis.

Which test is used in the lecture to investigate PCH?

The Donath-Landsteiner test.

Which Glob antibody is associated in the lecture with spontaneous abortion?

Anti-PP1Pk.

What exposures/conditions are listed in association with anti-P1?

"Pigeon eggs, hydatid cysts, and liver flukes."

"Which pathogens/toxins use P1 as a receptor?"

Shiga toxin and E. coli are listed.

Which two gene systems are important for determining Lewis phenotype?

The Lewis gene and the Secretor gene.

What type of carbohydrate chains are involved in the Lewis system?

Type 1 chains.

"Are Lewis antigens found on fetal red cells?"

No; the lecture states that type 1 chains are not found on fetal cells.

What Lewis phenotype change may occur temporarily during pregnancy?

Pregnant individuals often transition temporarily to Le(a−b−).

What does the Secretor gene do in Lewis antigen formation?

It converts a type 1 chain into H substance.

What does the Lewis gene enzyme do to produce Le(a)?

It adds fucose to a type 1 chain.

What does the Lewis gene enzyme do to produce Le(b)?

It adds fucose to a type 1 H chain.

What are key general characteristics of Lewis antibodies?

"They can be naturally occurring, may appear during pregnancy, and are usually IgM."

What substance can neutralize Lewis antibodies?

Saliva.

Are Le(a) and Le(b) antithetical antigens?

No; the lecture states that they are not antithetical.

Do Lewis antibodies show dosage?

No.

What structural difference distinguishes i from I antigens?

i is a linear chain; I is a branched chain.

Are I antigens present on cord cells?

I is not found on cord cells at birth.

When does I antigen begin to appear after birth?

It gradually appears over the first 18 months.

What are the general characteristics of antibodies in the I system?

"They are naturally occurring, usually IgM, and may be enhanced by enzymes."

What autoantibody is very common in adults in the I system?

Auto-anti-I; the lecture says it is found in most adults.

"What can neutralize anti-I?"

Human milk.

At what temperatures do typical I antibodies tend to react best?

They favor cold temperatures.

What is anti-IH directed against?

A compound antigen formed by I and H antigens.

"In which ABO subgroup does anti-IH tend to appear?"

A1 patients.

What defines Cold Agglutinin Disease (CAD) in the lecture's I-system section?

"High titers of auto-anti-I that react at warmer temperatures, around 30-32°C."

Which infection is listed as stimulating a strong cold auto-anti-I?

Mycoplasma pneumoniae.

Which other viral infection is associated with the I-system section?

"Epstein-Barr virus, associated with infectious mononucleosis."

Which autoantibody is listed separately in the I-system disease associations?

Auto-anti-i.

What does the ii phenotype mean in the I system?

A rare adult phenotype in which branched I chains never develop.

What is the frequency/significance profile of Lutheran antigen Lu(a)?

Lu(a) is low-frequency; the lecture notes mixed-field-like reactivity and says its clinical significance is questionable.

What is the frequency/significance profile of Lutheran antigen Lu(b)?

Lu(b) is high-frequency and described as significant.

"What is In(Lu) in the Lutheran system?"

A dominant inhibitor.

Which Lutheran phenotype is labeled as a true null in the lecture?

LuLu.

What antibody may a person with the Lutheran true-null phenotype make?

"Anti-Lu(a,b), as written in the lecture."

What does HTLA stand for?

"High Titer, Low Avidity."

What are Chido and Rogers antigens associated with?

C4d adsorbed onto red blood cells.

How can Chido/Rogers antibodies be neutralized?

With plasma.

What are Bennett-Goodspeed (Bg) antigens described as?

Remnants of HLA on red blood cells.

"How can Bg antibodies be neutralized?"

With chloroquine.

What are examples of Bg antigen specificities?

Bg(a) and Bg(b).

What protein function is associated with the Diego blood group system?

It acts as an anion exchanger.

What are the two Diego antigens named in the lecture?

Di(a) and Di(b).

What is the frequency and population distribution of Di(a)?

"Di(a) is low-frequency and is noted in Native American populations, especially South Americans, and in Mongolian populations."

What is the frequency of Di(b)?

Di(b) is high-frequency.

What clinical significance is noted for Diego antibodies?

They can be clinically significant; the lecture also flags mother/baby studies.

How may antibodies to high-frequency antigens initially resemble other antibodies?

"They can resemble warm autoantibodies, but require further investigation."

What workup steps are recommended for suspected high-frequency antibodies?

"Use special high-frequency panels, obtain a thorough patient history, and perform full antigen typing to look for an unusual antigen pattern."

How are antibodies to low-frequency antigens commonly discovered?

"Often incidentally, such as during an incompatible crossmatch or unexplained panel reactivity."

What workup steps are recommended for suspected low-frequency antibodies?

Use a special low-frequency panel and obtain a thorough patient history; antigen typing is less helpful.

What is the Hardy-Weinberg equation for gene frequencies?

p + q = 1.

What is the Hardy-Weinberg equation for genotype frequencies?

p² + 2pq + q² = 1.

"In Hardy-Weinberg terms what do p and q represent?"

The frequencies of two alleles in a population.

"In Hardy-Weinberg terms what do p² 2pq and q² represent?"

"The frequencies of the two homozygous genotypes and the heterozygous genotype, respectively."

"The lecture asks: if anti-K reacts with 9% of a population what percentage is k-negative? What assumption is needed to calculate this?"

"Assume Hardy-Weinberg equilibrium and that 9% of people express K (KK or Kk), so 91% are kk."

"Using the lecture's Hardy-Weinberg question if 9% are K-positive approximately what percentage are k-negative (lack the k antigen)?"

"Let K allele frequency be p and k allele frequency be q. Since kk = 0.91, q = √0.91 ≈ 0.9539 and p ≈ 0.0461. K-negative (KK) = p² ≈ 0.00212, or about 0.21%. This interpretation assumes K and k are the two alleles and Hardy-Weinberg equilibrium."

What is the difference between a high-frequency and low-frequency antigen in practical antibody investigation?

Antibodies to high-frequency antigens may make most routine cells reactive and need specialized panels plus careful antigen typing; antibodies to low-frequency antigens are often found incidentally and may require a special low-frequency panel.

Why is a detailed patient history important when investigating unusual blood bank reactivity?

The lecture specifically recommends a thorough patient history for both high-frequency and low-frequency antibody investigations.