Blood groups Flashcards

(16 cards)

1
Q

True or False: The ABO system is a protein based system.

A

False: it is a carbohydrate based system.

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2
Q

What system does Rh belong to?

A

It is a protein based system.

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3
Q

How many alleles are involved in the ABO system and what are the names?

A

There are three alleles; IA, IB and IO. It stands for Isoagglutinin.

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4
Q

What enzyme does the A allele code for?

A

N-acetyl-galactosaminyl transferase.

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5
Q

What enzyme does the B allele code for?

A

D-galactosyl transferase.

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6
Q

How can you differ between the type of precursor chains?

A

It depends where the Galactose binds to the sub-terminal N-acetylglucosamine(GlcNAc).

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7
Q

Explain the details of Type 1 chains?

A

They are primarily glycoproteins, they are found in secretions, it is a Beta1-3 linkage.

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8
Q

Explain the details of Type 2 chains?

A

They are primarily glycolipids, found on cell surface, Beta1-4 linkage.

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9
Q

FUT2 gene codes for a1,2-fucosyl transferase 2, what type of chain does this enzyme add fucose to?

A

It adds it to a type 1 chain making a Type 1 H antigen.

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10
Q

FUT1 gene codes for a1,2-fucosyl transferase 1, what type of chain does this enzyme add fucose to?

A

It adds it to a type 2 chain making a Type 2 H antigen.

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11
Q

What blood group is an individual if no A or B antigen is attached to the H antigen?

A

They will be blood group O.

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12
Q

What mutation causes the bombay phenotype?

A

It is caused by a mutation in FUT1 therefore no H antigen expression on type 2 chains. This causes a lack of A and B antigens as they require H antigen to be expressed therefore the individual appears to be blood group O. Their serum will contain anti-A, anti-B and anti-H therefore can only receive blood from other bombay blood. This is shown as h/h.

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13
Q

Why does inactive FUT2 gene not lead to bombay phenotype?

A

This does not lead to bombay phenotype because this is the secretor gene which creates type 1 H antigens allowing expression within secretions such as saliva therefore does not effect the cells. Inactive FUT2 is shown as se/se.

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14
Q

How many subgroups of A antigen are there and what are they?

A

There are 5 groups called: A1, A2, A3, Ax and Ael. Over 99% are either A1 or A2 but these code for different transferases. A2 is less efficient in converting H therefore RBCs have 20-25% less A antigens than A1 cells.

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15
Q

What are the main antigens that are of concern in the Rh system in order of how immunogenic they are?

A

D, c, E, C and e.

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16
Q

RBCs without any Rh proteins are stomatocytic and spherocytic which leads to haemolytic anaemia why does this happen?

A

Rh proteins are crucial to the membrane of RBCs as they mediate interatactions with the cytoskeleton and have a role in ammonia transport.