Lecture 19 + 20 - blood groups Flashcards

1
Q

what are surface antigens composed of

A

glycoproteins
glycolipids

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2
Q

what chromosome are genes encoding ABO antigens on

A

chromosome 9

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3
Q

what do ABO genesdo

A
  • produce glycotransferases
  • add sugars to H substance (by making the enzymes that are responsible for adding it)
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4
Q

what does O gene add to H substance

A

no effect

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5
Q

what does group A gene add to H substance

A

N-acetyl galactosamine (GlcNAc)

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6
Q

what does group B add to H substance

A

D-galactose (Gal)

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7
Q

what is the cause of productions of antibodies

A

produced in response to the environemnt
as many things in nature have similar complexes to RBC sugars = elicit production of antibodies

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8
Q

what antibodies does AB type have

A

none

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9
Q

what antibodies does O type have

A

anti A and anti B

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10
Q

subtypes of type A and their prevelance

A

A1 = 80%
A2 = 20%

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11
Q

when might subtypes create an issue for transfusion

A

repeated transfusions can cause a reaction

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12
Q

what is the Bombay phenotype

A
  • cant form 2-L-fucosyltransferase necassary for H substance formation
  • so NO h substance
  • and so present as O type
  • but they have antibodies to A, B (like O) and H substance
  • but when transfused with O = agglutinates
  • can only have blood from eah other
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13
Q

all the antigens of Rh blood group system

A

C
c
D (biggest clinical influence)
E
e

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14
Q

what are the genes for the Rh blood system

A

RhD = codes proteins with D antigen
and RhCE = codes for RhCE protein with C, c, E and e antigens

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15
Q

RHD gene

A

on chromosome 1
is dominant
if you inherit even one Rh+ then you are positive

its either present or not

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16
Q

RHCE gene

A

can have 4 variations

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17
Q

what is R0 blood type

A

someone with R0 is always +ve, and has Dce
so always have the D gene

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18
Q

what happens when someone has medical conditions that require mutiple blood transfusions

A

need more extensively matched blood
so instead of just matching ABO and Rh +ve or -ve
they need to match the subtype also
e.g. R0 matching

19
Q

which group are more donors needed

A

R0 subtype rare
and is 10x more common in Black african/black carribean backgrounds
so there’s a push for them to donate more

and theyre also at more risk of SCD, which need regular transfusions

20
Q
A
21
Q

in a Rh -ve mum and Rh +ve baby, what happens if the blood mixes and explain HDN

A

when blood mixes
mum’s immune system mounts a response against the Rh+ve antigens

But usually at delivery there’s no time for them to react ie an immune response to take place (usually takes 72hrs)
But the antibodies remain in the blood

So in first pregnancy theres no impact

BUT

In second, antibodies are already there

in second, when blood mixes, it can cause immune response and causes haemolytic disease of newborn

22
Q

what can women be given for haemolytic disease of newborn

A

if baby is Rh +ve = anti d immunoglobulin is given

= destroys the foetus’ Rh +ve D cells before they can cause the mum to produce her own anti D

23
Q

how might ABO haemolytic disease of newborn occur

A

happens to group A or B babies born to group O mothers (they have anti A and anti B antibodies)

24
Q

how is blood group O associated with blood clotting

A

usually blood groups dont have any link with helath conditions
but blood group O will have 25% less efficient factor 8 and vWF

25
Q

def of blood transfusion

A

transfer of blood or blood based products from one person into the circulation of another

26
Q

what do the plastic bags contain

A

anticoagulant

27
Q

process of blood transfusion from donor to patient

A

donor blood screened
components seperated from whole blood
goes to hospital blood bank
then to ward
then to patient

28
Q

what is whole blood seperated into

A

cellular components ie red cells, platelets, white cells
and
fresh plasma

29
Q

how much is one unit of red cells blood

A

280ml
(leucodepleted)

30
Q

how much does each unit of red cells increase the Hb

A

10g/L

31
Q

how long does red cell transfusion take

A

2-4 hrs

32
Q

what temp is red cell blood stored

A

4 deg celcius

33
Q

what is shelf life of red cells

A

up to 35 days
(the older the blood, the more affinity of O2 it has)

34
Q

what is the universal donor

A

O neg

35
Q

universal recipient?

A

AB +ve

36
Q

how much is one unit of fresh frozen plasma (FFP)

A

200-250ml

37
Q

temp. of FFP

A

-30 deg cel

38
Q

what does FFP contain

A

all coagulation factors
is group specific

39
Q

shelf life of FFP

A

36 months when frozen
and 24hrs after thawing

40
Q

how much is one adult dose of platelets taken from

A

4 different platelet donations
(isnt group specific)

41
Q

what does ABO forward group test for

A

adding red cells to first 4 columns
tests for antigens on the cell surface (A, B and D antigens)

42
Q

what does ABO reverse group test for

A

adding plasma to last 2 columns
checks for antibodies in the plasma

43
Q

what is a crossmatch

A

patient plasma mixed with donor’s red cells to ensure compatibility

44
Q
A