Unit 1b: ABO and H Blood Group Systems

What is the basic unit of inheritance composed of DNA?

gene

What is an alternate form of a gene?

allele

______________ is defined as the genetic make-up of an individual or the actual genes located on the chromosomes.

genotype

_________________ is defined as the inherited traits expressed by an individual that are detectable by testing.

phenotype

True or False: ABO antibody levels remain stable throughout adult life.

False (decrease with age or in immune diseases)

Genes code for the protein enzyme: ___________, which attaches sugars that attach to their related A, B, or H antigens. (gene - protein/enzyme - sugars - antigen)

glycosyltransferase

An individual must first inherit the ___ gene in order to have A or B antigens on their RBCs.

H gene (H/H or H/h)

The O typing is an _______, meaning people with this gene will have no enzymes on their RBCs besides H.

amorph

ABO antigens are (IgM/IgG) in nature.

IgM

H antigen is expressed in what chromosome?

19

ABO antigens are expressed in what chromosome?

9

True or False: Antigens are inherited.

false - enzymes that code for the antigens are inherited

What sugar is added to H antigens to form A antigens?

N-Acetylgalactosamine

The most common (80% of type A) subgroup of A phenotype is:

A1

Why are individuals with type A2 blood not always able to receive type A blood?

some A2 types produce alloantibodies to type A1, which makes up a majority of people with A type blood

Dolichos biflorus is a lectin that tests for the:

• A1 antigen

• A2 antigen

• H antigen

• B antigen

A1 antigen

What sugar is added to H antigens to form B antigens?

D-Galactose

Individuals who did not inherit the H gene (have h/h) are said to have the __________ phenotype Oh.

Bombay

Detecting for the presence of lack of presence of antigens on a patient’s RBCs is called _____ typing.

front

______ typing is used to confirm a patient’s blood type by testing their antibodies in their serum.

Back

The actual blood type of the patient is based on the (front/back) type reaction.

front

Anti-H reacts strongest with ____ cells

• A1 cells

• A2 cells

• B cells

• O cells

O cells

Reactions:

Patient cells react with Anti-A and Anti-B

Patient serum does not react with A cells or B cells.

The patient's ABO typing is:

• A

• B

• AB

• O

AB

ABO antisera is expected to react:

• at room temperature

• after a 37 incubation

• at AHG phase of testing

• at 4 C

at room temperature

Anti-A and anti-B:

• React best at room temperature or colder

• Agglutinate saline suspended red blood cells

• Are capable of hemolysis

• All of the above

All of the above

The products of genes inherited at the ABO locus are:

• Protein rbc antigens

• Carbohydrate soluble antigens

• Immunodominant sugars

• Glycosyltransferases

Glycosyltransferases

Which of the following accurately describes the H/h antigens?

• h gene is an amorph

• One H gene must be inherited for the normal expression of ABO antigens

• A or B specific sugars are attached to the H antigen by enzymes

• All of the above

All of the above

All of the following accurately explains how A1 and A2 subgroups differ except:

• The antigens are qualitatively or physically different

• The A2 antigen will not react with the anti-A blood typing reagent.

• The A2 subgroup has fewer A antigen sites and more H antigen sites than the A1 subgroup

• Only A1 antigens react with Dolichos biflorus lectin

The A2 antigen will not react with the anti-A blood typing reagent.

True or False: ABO antibody production begins at 2-4 years of age.

false - 4-6 months of age

The inheritance pattern of the ABH antigens is:

• sex-linked dominant/codominant

• sex-linked recessive

• autosomal dominant/codominant

• autosomal recessive

autosomal dominant/codominant

Type ______ blood group is considered a universal donor for red blood cell transfusions and type _______ is the universal donor for plasma transfusions.

O (lacks antigens that could react with patient antibodies)

AB (lacks antibodies that could react with patient antigens)

An excess of antibody is known as:

prozone

An excess of antigen is known as:

postzone

An anamnestic response produces (IgM/IgG) antibodies.

IgG

When are IgM antibodies considered clinically significant?

when they react at body temp (37C)