8/25- Transfusion: ABO-Rh and Compatability Flashcards Preview

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Flashcards in 8/25- Transfusion: ABO-Rh and Compatability Deck (27):
1

What genes are at play in the ABO blood group system?

Chromosomes?

What are their gene products?

H gene (chr. 19)

- Produces H substance (a carbohydrate)

ABO gene (chr. 9)

Products act on H substance

- A gene: 1,3-N acetylgalactosaminyl

- B gene: 1,3-galactosyl transferase

- O gene: produces a serum protein product which has no known enzymatic activity

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2

What kind of genotype/phenotype relation does ABO blood-typing have?

Co-dominance 

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3

When do ABO antibodies arise? What kind of Abs are they?

Anti-A and anti-B Abs are naturally occurring appear spontaneously at 5-6 mo after birth (anti-A, anti-B, antiA,B)

- No need for prior transfusion

- Mostly IgM and some portion is IgG

- Universal blood = type O

- Universal plasma = type AB! 

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4

What is the effect of ABO antibodies?

Complement activating

-> intravascular hemolysis

-> severe hemolysis/DIC/death

5

How is ABO grouping determined?

2 tests are used to determine ABO of transfusion recipient to prevent typing error

- Cell/Forward typing: detection of antigens on RBC by anti-A and anti-B antisera

- Serum/Reverse typing: detection of anti-A and anti-B antibodies by the use of known A and B cells RBC + plasma/reagents -> agglutination

6

Screening results by blood type: 

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7

What is the interpretation of this typing?

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Group A

8

FYI? Frequency of ABO blood groups in the US?

O > A > B > AB 

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9

ABO blood and plasma compatability?

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10

What is Rh?

- Stands for Rhesus (Rhesus monkey)

- There are 56 Rh antigens known

11

What are the 5 important Rh antigens?

D locus: D- most immunogenic (commonly referred to as Rh type)

C locus: C and c

E locus: E and e

12

Rh is synonymous with what?

D (Rh typing means D antigen typing)

So basically, in naming: A pos = A, D positive

13

What is the Rh type based on the following results? 

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14

Frequency of Rh positive and negative phenotypes in the population

- Positive >> negative

- Basically, if you're Asian and Rh-, it's most likely a mistake/artifact

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15

What genotypes reusult in the + and - Rh phenotypes?

Rh positive: DD or Dd

Rh negative: dd

16

ABO/Rh percentages in Houston?

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17

Do antibodies form to Rh?

- Rh negative individuals do not have anti-Rh; it is NOT naturally occurring/spontaneously developed

- It may be developed post transfusion of Rh positive RBCs or pregnancy or transplant!!

18

Describe the sensitization of Rh negative individuals to Rh

- 80% of Rh- (healthy) will become sensitized after receiving 1 unit of Rh+ RBCs

- 10% will become sensitized after delivering Rh+ baby if untreated with Rh immunoglobulin

19

How to handle pregnant Rh- moms?

Rhogram (Rh immunoglobulin)

20

What can Rh antibodies cause (when an Rh- person with antibodies receive Rh+ blood)?

- Severe hemolytic disease of fetus and newborn (HDFN)

- Hemolytic transfusion reaction (HTR)

21

T/F: Rh+ platelet transfusion can lead to sensitization. Consequences?

True! (under 2 mL of RBC)

- Rh- cellular blood products (RBC and platelets) to Rh- women of reproductive age whenever possible

22

T/F: Group A is the most common ABO among all races

False; Type O is the most common

23

T/F: Type AB plasma can be safely transfused to any individual regardless of ABO type in an emergency

True

24

T/F: Rh negative individuals develop anti-Rh spontaneously by age 2 years

False

25

T/F: Approximately 15% of Caucasians are Rh negative

True (Asian Americans, almost never)

26

T/F: If both parents are A+ their children must also be A+

False

27

T/F: As risk of Rh sensitization is low, Rh positive RBC can be safely transfuse to Rh negative young women

False