Immunohematology Quiz 1

What are the five musts for the blood bank?

accreditation/certification

understanding abo and d antigens/antibodies and applying them to compatibility

ability to perform antibody screening and identifications and understanding which are clinically significant

knowledge of procedures and communication skills

a penchant for error identification and avoidance

What is the central dogma?

DNA-transcription-RNA-translation-PROTEIN

What are blood group antigens made out of?

Proteins or carbohydrates

What is an exon?

coding segments of informational sequences

What is an intron?

non-coding segments of DNA

What is a null phenotype?

RBC is antigen negative for all antigens in a specific blood group system

What is a single nucleotide variant?

a single base pair change has occurred in a gene

What is a missense mutation?

single base pair changed, leading to a different amino acid

What is the most common RBC genetic mutation type?

missense mutations

What is a nonsense mutation?

base pair change leading to a stop codon

What is the common result of a nonsense mutation?

no protein or a non-functional protein

What is an indel?

insertion or deletion of one or more nucleotides

What does N stand for when talking about genes?

the null gene

What is a frameshift mutation?

insertions or deletions of DNA, causes reading frame to be moved

What are splice sites?

junctions of the introns and exons where mRNA precursor is cut and joined

What can splice site mutations result in?

antigen negative RBCs, weak antigen expression, and "el" phenotypes

What is a locus?

position on a chromosome where the genes for a given trait are located

What are alleles?

alternate forms of a gene which occupy a single locus

What is hemizygous?

one allele is missing, only present on one member of the chromosome pair

most common alleles on the X chromosome in males

What is a phenotype?

The trait that is expressed

What is a genotype?

The combination of alleles which produce a trait

If *JKA is fully capitalized, what is is referring to?

The gene

If Jk^a is written like that, what is it referring to?

The antigen on the RBCs

What is a blood group antigen?

The chemical determinant/epitope on the surface of the RBC

What is a blood group system?

Blood group antigen alleles at a locus that are so closely linked that crossing-over between them either does not occur or is rare

What type of expression is most common in RBC antigens?

Codominant expression

What shows dosage (single vs double dose of an antigen? for RBCs?

Antibodies!

What is a double dose?

Homozygous for an antigen

What is a single dose?

Heterozygous for an allele

What is an amorph?

a gene that produces no detectable antigen product / a null or silent gene

T or F: Consanguineous families make rare blood antigens even less likely

False: consanguineous families cause rare blood groups even more common

What is autosomal dominant inheritance?

the affected parent can pass a normal gene or a diseased gene to offspring.

Rare for autosomal dominant genes to cause disease.

When one parent is a carrier and other is not then risk is for each child is 50%

What is autosomal recessive inheritance?

appears in children of unaffected parents, may skip generations, both males and females affected

What is X-linked dominant inheritance?

A dominant allele on the X chromosome: If the allele is inherited from either parent the offspring will be infected; cannot be passed from father to son

What is phenotype frequency?

proportion of individuals in a population that have a particular phenotype

all should add up to 100%

How do you find how many units you would likely have to type before finding a unit that matches the anitgens you need?

Take the frequency of one antigen and multiple it by the frequency of another (multiple the percentages as decimals), divide 1 by the decimal result, and that is on average how many untis you will have to type to find the blood you need

if you need multiple units, take the number of units you need, and divide it by the final decimal answer above

What is allele frequency?

the percentage that each allele contributes to the total pool of genes inherited at a single genetic locus

the sum of all frequencies for an allele at a given locus must be 1

What can you use the Hardy-Weinberg equation to calculate?

expected gene frequencies

phenotype frequencies

antigen frequencies

What is an antigen?

The part of a foreign substance that is capable of reacting with the products of the adaptive immune response

What is an epitope?

The portion of an antigen that is recognized by the products of the adaptive immune response

Is the IgM response larger after the first immunogenic stimulus or the second?

First

Is the IgG response larger after the first immunogenic stimulus or the second?

Second

What is evanescence?

When the antibody levels fall

What are the five types of immunoglobulins?

IgG, IgM, IgA, IgD, and IgE

(GAMED)

Which is the only Ig that is a pentamer?

IgM

Which two Igs are the main antibodies for blood groups?

IgG and IgM

Which three Igs have hinge joints?

IgG, IgD, and IgA

What type of bonds hold together Ig hinge joints?

Disulfide bonds

Which Ig is the largest?

IgM

Which ig is in the highest concentration in the plasma?

IgG (specifically IgG1)

Around what is the half-life for IgG?

~20 days

Which Igs can activate the complement cascade?

IgG and IgM

Which Ig can cross the placenta?

IgG (specifically IgG2)

Which antigen and Ig cause hemolytic disease of the fetus and newborn?

Rh and IgG

Is the Rh antigen a protein or carbohydrate antigen?

Protein

Are the ABO antigens protein or carbohydrate antigens?

Carbohydrate

What are glycopsphingolipids?

Carbohydrates that are covalently attached to the lipids of the cell membrane

What are glycoproteins?

Carbohydrates that are covalently attached to proteins of the cell membrane

How do genes code for carbohydrate antigens?

They code for a specific glycosyltransferase that creates the carbohydrate

What is extravascular hemolysis?

Hemolysis not done in the vasculature

done by macrophages, usually in the spleen or liver

What is intravascular hemolysis?

hemolysis that occurs in the vasculature

complement mediated

Which is more damaging, extravascular or intravascular hemolysis?

Intravascular

Releases the cell products into the blood stream directly

Which type of Ig does not need prior exposure to be produced?

IgM

Which type of Ig must have prior exposure to be produced?

IgG

What is an alloantibody?

An antibody formed in response to pregnancy, transfusion or transplant targeted against a antigen that is not present on the patient's RBC's

What is an autoantibody?

An antibody produced by the immune system that is directed against one or more of the individual's own proteins

Which complement protein is used as a marker that a patient has antibodies for certain antigens?

C3d

How many complement pathways are there?

3

Which IgG most commonly activates complement?

Ig3

How does the concentration of antigens on the surface of the cell affect the complement response?

The more antigens, the stronger the response

Directly proportional

What is the final result of the complement cascade?

The membrane attack complex (MAC)

At what point can the complement cascade be either multiplied or inhibited?

C3b

T or F: spherocytes can appear in circulation after complement has been activated and then stopped at C3b

True

T or F: All alloantibodies always bind complement

False: there are three different occurrences--most, some, and rare binding