L4- blood groups

3 types of blood

• a

• B

• O

Which is the less common blood group

AB

What is blood group/type

The classification of blood based on presence or absence of inherited antigenic substances on the surface of rbcs

Antigen

A material not found in the host and considered frorgein that provokes an immune response

Red blood cell surface antigen

Complex mixture of protines, glycoproteins and glycolipids found on the surface of all red blood cells and a range of other cells in the body

How many blood gourd systems are known

43

How many blood group antigens have been described

>600

Complete blood group

The full set of surface antigens on a persons rbc

What contributes to blood group (5)

• inheritance

• Infection

• Malignancy

• Autoimmune disease

• After bone marrow transplant

How does myeloid leukaemia affect blood group

Can lead to changes that weake the antigen making people present as o blood group rather than a or b

What are the 5 sugars involved in the ABO system. Name the most important 3 first

• fuctose

• Galactose

• N-acetylgalactosamine

• N-acteylglucosamine

• Salic acid

What are the 3 enzymes involved in ABO system ad what class of enzymes are they

• fucosyl transferase (FUT1)

• N-acetyl galactosamine (A Transferase)

• Galactose transferase (B transferase)

• Are glycosyl transferases

What are the 2 genes involved int he ABO system

• ABO

• H

What is the ABO blood group determined by

the terminal sugar structure of substances found on surface of rbcs

What do the ABO and H genes encode for and what does this do

Glycosyltrasnferases→ transfer monosaccharides to polysaccharide chains

What are the 3 possible allles of teh ABO gene and what are their relative dominance’s

• A,B and O

• A and B are dominant to O

What does the o allele encode for

A truncated non

What allele does the H gene have

H and h

What does H code for

Fucosyl transferase (FUT1)

What does FUT1 do

Adds a fucose to the pre cursor glycoprotein on the surface of RBCs to form a H antigen/substance

Which chromomes is H/h found on

19

Which allele combination makes H substance

HH and Hh individuals → hh do NOT

Which allele combination is called the Bombay phenotype

hh

Features of Bombay phenotype (2)

• very rare (1 in 1,000,000) except ni parts of india where it is i in 8000

• Has no symptoms or related disease but hh individuals can only receive transfusions from others with the same blood group

Where is the ABO gene found

The seven exon on chromomse. 9

What made the o allele

A deletion in exon 6 due to framshift mutation making an inactive protein

What is the difference between teh A and B alleles

They differ by 7 nucleotide substitutions → 4 translate into amino acid differences in the gene product

What determines a or b specificity of glycosyltrasnferase that they encode

Residuces at positions 266 and 268

Which trasnferase makes a substance

A trasnferase (N-acetyl galactosamne trasnferase)

Which trasnferase makes b substance

B- galactose transferase

Why cant hh individuals make ABO antigens

Dont have functional FUT1 genes so cant make substance H so cant make ABO antigens

What are the six genotype ABO allel Indian ale can be

• AA

• AO

• BB

• BO

• AB

• OO

What substance does AA make

A substance only

What substance does AO make

AO

What substance does BO make

Makes b substance only

What substance does BB substance

B substance only

What substance does AB make

A and B

What substance does OO make

H substance

What diseases are inked to ABO phenotype

• gastric cancer in a group individuals

• Increase occur endo fo gastric and duodenal ulcers in group o individuals

What does ABO correlate with

Levels of factor VIII and con Willebrand factor

Why do A, B and H provoke an immune response

They are glycoproteins and therefore antigenic

What are blood group antigens also known as

Agglutinogens

What are the antibodies raised against blood group antigens also known as

Agglutinins

What will happen if two different blood groups are mixed

The opposing antibodies will causes clumping (agglutination) of the donated RBCs

What does agglutination result in

RBClysis

What does ABo blood group incompatibility lead to (6)

• donated RBCs lyse in the blood vessles

• Complement system is activated

• Leads to kidney failure

• Uncontrolled clotting

• Circulatory shock

• Can be fatal

What kind of moelcuels are rhesus proteins

Protines

How many rhesus antigens can be present on the rbc

Over 49

Which is the most common And important rhesus antigen

The D antigen

Which individuals are Rh+

Those who are homozygous dominant (DD) or heterozygous (Dd)

Which individuals are Rh negative

Homozygous recessive (dd)

What s the rarest blood type

Golden blood→ less than 50 incidences worldwide

What antibody do golden rice individual not have

No Rh antibody

Who can golden rice individuals not recieve donation from / give donations to

Can only receive donations from other Rh null individuals but can donate to any ABO

What condition is associated with golden rice blood and why

Haemolytic anaemia→ RBCs have a shortened life

Distributions of rhesus group d antigen by race

Asian-99%

Black-92%

Caucasian-82%

What is the orle of the RhD antigen (2)

Membrane stability and ammonia transport

What are anti-Rh(D) antibodies produced by

Not normally produced by sensitisation to Environemtnal antigens→ exposure is needed

What do Anti-Rh(D) antibodies desotyred and how

Destoryed any Rh(D)+ RBCs they come into contact with

• the rbc is bound by IgG, engulfed by macrophages, transported to the liver and spleen for removal

• Less serious than intramuscular haemolytic

Stages of haemolytic disease of the newborn (4)

• Rh+ father and Rh- carrying mother have a child

• The Rh antigens form the developing foetus can enter the mothers blood and are recognised as foreign so makes antibodies against it

• They have a second child and her mother is exposed again

• The anti rh antibodies from the mother cross the placenta and damge the foetal rbcs causing anaemia, jaundice and sometimes death